Question: What are the observed mutations in the SARS-CoV-2 genome and how often do the mutations occur?

Title: Overwhelming mutations or SNPs of SARS-CoV-2: A point of caution Content: The morbidity of SARS-CoV-2 (COVID-19) is reaching 3 Million landmark causing and a serious public health concern globally and it is enigmatic how several antiviral and antibody treatments were not effective in the different period across the globe. With the drastic increasing number of positive cases around the world WHO raised the importance in the assessment of the risk of spread and understanding genetic modifications that could have occurred in the SARS-CoV-2. Using all available deep sequencing data of complete genome from all over the world (NCBI repository), we identified several hundreds of point mutations or SNPs in SARS-CoV-2 all across the genome. This could be the cause for the constant change and differed virulence with an increase in mortality and morbidity. Among the 12 different countries (one sequence from each country) with complete genome sequencing data, we noted the 47 key point mutations or SNPs located along the entire genome that might have impact in the virulence and response to different antivirals against SARS-CoV-2. In this regard, key viral proteins of spike glycoprotein, Nsp1, RdRp and the ORF8 region got heavily mutated within these 3 months via person-to-person passage. We also discuss what could be the possible cause of this rapid mutation in the SARS-CoV-2.

Title: SARS-CoV-2 genome evolution exposes early human adaptations Content: The set of mutations observed at the outset of the SARS-CoV-2 pandemic may illuminate how the virus will adapt to humans as it continues to spread. Viruses are expected to quickly acquire beneficial mutations upon jumping to a new host species. Advantageous nucleotide substitutions can be identified by their parallel occurrence in multiple independent lineages and are likely to result in changes to protein sequences. Here we show that SARS-CoV-2 is acquiring mutations more slowly than expected for neutral evolution, suggesting purifying selection is the dominant mode of evolution during the initial phase of the pandemic. However, several parallel mutations arose in multiple independent lineages and may provide a fitness advantage over the ancestral genome. We propose plausible reasons for several of the most frequent mutations. The absence of mutations in other genome regions suggests essential components of SARS-CoV-2 that could be the target of drug development. Overall this study provides genomic insights into how SARS-CoV-2 has adapted and will continue to adapt to humans. SUMMARY In this study we sought signals of evolution to identify how the SARS-CoV-2 genome has adapted at the outset of the COVID-19 pandemic. We find that the genome is largely undergoing purifying selection that maintains its ancestral sequence. However, we identified multiple positions on the genome that appear to confer an adaptive advantage based on their repeated evolution in independent lineages. This information indicates how SARS-CoV-2 will evolve as it diversifies in an increasing number of hosts.

Title: Mutation landscape of SARS-CoV-2 reveals three mutually exclusive clusters of leading and trailing single nucleotide substitutions Content: The COVID-19 pandemic has spread across the globe at an alarming rate in the last four months. However, unlike any of the previous global outbreaks the availability of hundreds of SARS-CoV-2 sequences provides us with a unique opportunity to understand viral evolution in real time. We analysed 480 full-length (>29000 nt) sequences from the 1575 SARS-CoV-2 sequences available and identified 37 single-nucleotide substitutions occurring in >1% of the genomes. Majority of the substitutions were C to T or G to A. We identify C/Gs with an upstream TTT trinucleotide motif as hotspots for mutations in the SARS-CoV-2 genome. Interestingly, two of the 37 substitutions occur within highly conserved secondary structures in the 5’ and 3’ untranslated regions that are critical for the virus life cycle. Furthermore, clustering analysis revealed unique geographical distribution of SARS-CoV-2 variants defined by their mutation profile. Of note, we observed several co-occurring mutations that almost never occur individually. We define 3 mutually exclusive lineages (A1, B1 and C1) of SARS-CoV-2 which account for about three quarters of the genomes analysed. We identify lineage-defining leading mutations in the SARS-CoV-2 genome which precede the occurrence of sub-lineage defining trailing mutations. The identification of mutually exclusive lineage-defining mutations with geographically restricted patterns of distribution has potential implications for diagnosis, pathogenesis and vaccine design. Our work provides novel insights on the temporal evolution of SARS-CoV-2.

Title: How fast does the SARS-Cov-2 virus really mutate in heterogeneous populations? Content: We introduce the problem of determining the mutational support of genes in the SARS-Cov-2 virus and estimating the distribution of mutations within different genes using small sample sizes that do not allow for accurate maximum likelihood estimation. The mutational support refers to the unknown number of sites mutated across all strains and individual samples of the SARS-Cov-2 genome; given the high cost and limited availability of real-time polymerase chain reaction (RT-PCR) test kits, especially in early stages of infections when only a small number of genomic samples (∼ 1000s) are available that do not allow for determining the exact degree of mutations in an RNA virus that comprises roughly 30, 000 nucleotides. Nevertheless, working with small sample sets is required in order to quickly predict the mutation rate of this and other viruses and get an insight into their transformational power. Furthermore, with the small number of samples available, it is hard to estimate the mutational landscape across different age/gender groups and geographical locations which may be of great importance in assessing different risk categories and factors influencing susceptibility to infection. To this end, we use our state-of-the art polynomial estimator techniques and the Good-Turing estimator to obtain estimates based on only roughly 1, 000 samples per category. Our analysis reveals an interesting finding: the mutational support appears to be statistically more significant in patients which appear to have lower infection rates and handle the exposure with milder symptoms, such as women and people of relatively young age (≤ 55).

Title: Rampant CâU Hypermutation in the Genomes of SARS-CoV-2 and Other Coronaviruses: Causes and Consequences for Their Short- and Long-Term Evolutionary Trajectories Content: The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has motivated an intensive analysis of its molecular epidemiology following its worldwide spread. To understand the early evolutionary events following its emergence, a data set of 985 complete SARS-CoV-2 sequences was assembled. Variants showed a mean of 5.5 to 9.5 nucleotide differences from each other, consistent with a midrange coronavirus substitution rate of 3 × 10-4 substitutions/site/year. Almost one-half of sequence changes were CâU transitions, with an 8-fold base frequency normalized directional asymmetry between CâU and UâC substitutions. Elevated ratios were observed in other recently emerged coronaviruses (SARS-CoV, Middle East respiratory syndrome [MERS]-CoV), and decreasing ratios were observed in other human coronaviruses (HCoV-NL63, -OC43, -229E, and -HKU1) proportionate to their increasing divergence. CâU transitions underpinned almost one-half of the amino acid differences between SARS-CoV-2 variants and occurred preferentially in both 5' U/A and 3' U/A flanking sequence contexts comparable to favored motifs of human APOBEC3 proteins. Marked base asymmetries observed in nonpandemic human coronaviruses (U â« A > G â« C) and low G+C contents may represent long-term effects of prolonged CâU hypermutation in their hosts. The evidence that much of sequence change in SARS-CoV-2 and other coronaviruses may be driven by a host APOBEC-like editing process has profound implications for understanding their short- and long-term evolution. Repeated cycles of mutation and reversion in favored mutational hot spots and the widespread occurrence of amino acid changes with no adaptive value for the virus represent a quite different paradigm of virus sequence change from neutral and Darwinian evolutionary frameworks and are not incorporated by standard models used in molecular epidemiology investigations.IMPORTANCE The wealth of accurately curated sequence data for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), its long genome, and its low substitution rate provides a relatively blank canvas with which to investigate effects of mutational and editing processes imposed by the host cell. The finding that a large proportion of sequence change in SARS-CoV-2 in the initial months of the pandemic comprised CâU mutations in a host APOBEC-like context provides evidence for a potent host-driven antiviral editing mechanism against coronaviruses more often associated with antiretroviral defense. In evolutionary terms, the contribution of biased, convergent, and context-dependent mutations to sequence change in SARS-CoV-2 is substantial, and these processes are not incorporated by standard models used in molecular epidemiology investigations.

Title: Rampant C→U Hypermutation in the Genomes of SARS-CoV-2 and Other Coronaviruses: Causes and Consequences for Their Short- and Long-Term Evolutionary Trajectories Content: The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has motivated an intensive analysis of its molecular epidemiology following its worldwide spread. To understand the early evolutionary events following its emergence, a data set of 985 complete SARS-CoV-2 sequences was assembled. Variants showed a mean of 5.5 to 9.5 nucleotide differences from each other, consistent with a midrange coronavirus substitution rate of 3 × 10(−4) substitutions/site/year. Almost one-half of sequence changes were C→U transitions, with an 8-fold base frequency normalized directional asymmetry between C→U and U→C substitutions. Elevated ratios were observed in other recently emerged coronaviruses (SARS-CoV, Middle East respiratory syndrome [MERS]-CoV), and decreasing ratios were observed in other human coronaviruses (HCoV-NL63, -OC43, -229E, and -HKU1) proportionate to their increasing divergence. C→U transitions underpinned almost one-half of the amino acid differences between SARS-CoV-2 variants and occurred preferentially in both 5′ U/A and 3′ U/A flanking sequence contexts comparable to favored motifs of human APOBEC3 proteins. Marked base asymmetries observed in nonpandemic human coronaviruses (U ≫ A > G ≫ C) and low G+C contents may represent long-term effects of prolonged C→U hypermutation in their hosts. The evidence that much of sequence change in SARS-CoV-2 and other coronaviruses may be driven by a host APOBEC-like editing process has profound implications for understanding their short- and long-term evolution. Repeated cycles of mutation and reversion in favored mutational hot spots and the widespread occurrence of amino acid changes with no adaptive value for the virus represent a quite different paradigm of virus sequence change from neutral and Darwinian evolutionary frameworks and are not incorporated by standard models used in molecular epidemiology investigations. IMPORTANCE The wealth of accurately curated sequence data for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), its long genome, and its low substitution rate provides a relatively blank canvas with which to investigate effects of mutational and editing processes imposed by the host cell. The finding that a large proportion of sequence change in SARS-CoV-2 in the initial months of the pandemic comprised C→U mutations in a host APOBEC-like context provides evidence for a potent host-driven antiviral editing mechanism against coronaviruses more often associated with antiretroviral defense. In evolutionary terms, the contribution of biased, convergent, and context-dependent mutations to sequence change in SARS-CoV-2 is substantial, and these processes are not incorporated by standard models used in molecular epidemiology investigations.

Title: No evidence for increased transmissibility from recurrent mutations in SARS-CoV-2 Content: The COVID-19 pandemic is caused by the coronavirus SARS-CoV-2, which jumped into the human population in late 2019 from a currently uncharacterised reservoir. Due to this extremely recent association with humans, SARS-CoV-2 may not yet be fully adapted to its human host. This has led to speculations that some lineages of SARS-CoV-2 may be evolving towards higher transmissibility. The most plausible candidate mutations under putative natural selection are those which have emerged repeatedly and independently (homoplasies). Here, we formally test whether any of the recurrent mutations that have been observed in SARS-CoV-2 to date are significantly associated with increased viral transmission. To do so, we developed a phylogenetic index to quantify the relative number of descendants in sister clades with and without a specific allele. We apply this index to a carefully curated set of recurrent mutations identified within a dataset of over 23,000 SARS-CoV-2 genomes isolated from patients worldwide. We do not identify a single recurrent mutation in this set convincingly associated with increased viral transmission. Instead, recurrent SARS-CoV-2 mutations currently in circulation appear to be evolutionary neutral. Recurrent mutations also seem primarily induced by the human immune system via host RNA editing, rather than being signatures of adaption to the novel human host. We find no evidence at this stage for the emergence of more transmissible lineages of SARS-CoV-2 due to recurrent mutations.

Title: Sarbecovirus comparative genomics elucidates gene content of SARS-CoV-2 and functional impact of COVID-19 pandemic mutations Content: Despite its overwhelming clinical importance for understanding and mitigating the COVID-19 pandemic, the protein-coding gene content of the SARS-CoV-2 genome remains unresolved, with the function and even protein-coding status of many hypothetical proteins unknown and often conflicting among different annotations, thus hindering efforts for systematic dissection of its biology and the impact of recent mutations. Comparative genomics is a powerful approach for distinguishing protein-coding versus non-coding functional elements, based on their characteristic patterns of change, which we previously used to annotate protein-coding genes in human, fly, and other species. Here, we use comparative genomics to provide a high-confidence set of SARS-CoV-2 protein-coding genes, to characterize their protein-level and nucleotide-level evolutionary constraint, and to interpret the functional implications for SARS-CoV-2 mutations acquired during the current pandemic. We select 44 complete Sarbecovirus genomes at evolutionary distances well-suited for protein-coding and non-coding element identification, create whole-genome alignments spanning all named and putative genes, and quantify their protein-coding evolutionary signatures using PhyloCSF and their overlapping constraint using FRESCo. We find strong protein-coding signatures for all named genes and for hypothetical ORFs 3a, 6, 7a, 7b, and 8, indicating protein-coding roles, and provide strong evidence of protein-coding status for a recently-proposed alternate-frame novel ORF within 3a. By contrast, ORF10 shows no protein-coding signatures but shows unusually-high nucleotide-level constraint, indicating it has important but non-coding functions, and ORF14 and SARS-CoV-1 ORF3b, which overlap other genes, lack evolutionary signatures expected for dual-coding regions, indicating they do not produce functional proteins. ORF9b has ambiguous protein-coding signatures, preventing us from resolving its protein-coding status. ORF8 shows extremely fast nucleotide-level evolution, lacks a known function, and was deactivated in SARS-CoV-1, but shows clear signatures indicating protein-coding function worthy of further investigation given its rapid evolution and potential role in replication. SARS-CoV-2 mutations are preferentially excluded from evolutionarily-constrained amino acid residues and synonymously-constrained nucleotides, indicating purifying constraint acting at both coding and non-coding levels. In contrast, we find a conserved region in the nucleocapsid that is enriched for recent mutations, which could indicate a selective signal, and find that several spike-protein mutations previously identified as candidates for increased transmission and several mutations in isolates found to generate higher viral load in-vitro disrupt otherwise-perfectly-conserved amino-acids, consistent with adaptations for human-to-human transmission.

Title: Quantification of Intra-Host Genomic Diversity of SARS-CoV-2 Allows a High-Resolution Characterization of Viral Evolution and Reveals Functionally Convergent Variants Content: A global cross-discipline effort is ongoing to characterize the evolution of SARS-CoV-2 virus and generate reliable epidemiological models of its diffusion. To this end, phylogenomic approaches leverage accumulating genomic mutations as barcodes to track the evolutionary history of the virus and can benefit from the surge of sequences deposited in public databases. Yet, such methods typically rely on consensus sequences representing the dominant virus lineage, whereas a complex sublineage architecture is often observed within single hosts. Furthermore, most approaches do not account for variants accumulation processes and might produce inaccurate results in condition of limited sampling, as witnessed in most countries affected by the epidemics. We introduce VERSO (Viral Evolution ReconStructiOn), a new comprehensive framework for the characterization of viral evolution and transmission from sequencing data of viral genomes. our approach accounts for accumulation of clonal mutations and uncertainty in the data, by taking advantage of the achievements of research in cancer evolution, to deliver robust phylogenomic lineage models, and exploits intra-host variant frequency profiles to characterize the sublineage similarity among samples, which may derive from uncovered infection events. The application of our approach to RNA-sequencing data of 162 SARS-CoV-2 samples generates a high-resolution model of evolution and spread, which improves recent findings on viral types and highlights the existence of patterns of co-occurrence of minor variants, revealing likely infection paths among hosts harboring the same viral lineage. The in-depth analysis of the mutational landscape of SARS-CoV-2 confirms a statistically significant increase of genomic diversity in time and identifies a number of variants that are transiting from minor to clonal state in the population. We also show that standard phylogenetic methods can produce unreliable results when handling datasets with noise and sampling limitations, as proven by the further application of VERSO to 12419 consensus sequences included in GISAID database. Notably, VERSO allows to pinpoint minor variants that might be positively or negatively selected across distinct lineages, thus driving the design of treatments and vaccines. In particular, minor variant g.29039A>U, detected in multiple viral lineages and validated on independent samples, shows that SARS-CoV-2 can lose its main Nucleocapsid immunogenic epitopes, raising concerns about the effectiveness of vaccines targeting the C-terminus of this protein. Finally, we here release the likely SARS-CoV-2 ancestral genome, obtained by resolving ambiguous SNPs that distinguish two widely-used reference genomes from human samples, by employing the Pangolin-CoV and the Bat-CoV-RaTG13 genomes. Our results show that the joint application of our framework and data-driven epidemiological models might allow to deliver a high-resolution platform for pathogen surveillance and analysis.

Title: The origin and underlying driving forces of the SARS-CoV-2 outbreak Content: The spread of SARS-CoV-2 since December 2019 has become a pandemic and impacted many aspects of human society. Here, we analyzed genetic variation of SARS-CoV-2 and its related coronavirus and found the evidence of intergenomic recombination. After correction for mutational bias, analysis of 137 SARS-CoV-2 genomes as of 2/23/2020 revealed the excess of low frequency mutations on both synonymous and nonsynonymous sites which is consistent with recent origin of the virus. In contrast to adaptive evolution previously reported for SARS-CoV in its brief epidemic in 2003, our analysis of SARS-CoV-2 genomes shows signs of relaxation of selection. The sequence similarity of the spike receptor binding domain between SARS-CoV-2 and a sequence from pangolin is probably due to an ancient intergenomic introgression. Therefore, SARS-CoV-2 might have cryptically circulated within humans for years before being recently noticed. Data from the early outbreak and hospital archives are needed to trace its evolutionary path and reveal critical steps required for effective spreading. Two mutations, 84S in orf8 protein and 251V in orf3 protein, occurred coincidentally with human intervention. The 84S first appeared on 1/5/2020 and reached a plateau around 1/23/2020, the lockdown of Wuhan. 251V emerged on 1/21/2020 and rapidly increased its frequency. Thus, the roles of these mutations on infectivity need to be elucidated. Genetic diversity of SARS-CoV-2 collected from China was two time higher than those derived from the rest of the world. In addition, in network analysis, haplotypes collected from Wuhan city were at interior and have more mutational connections, both of which are consistent with the observation that the outbreak of cov-19 was originated from China. SUMMARY In contrast to adaptive evolution previously reported for SARS-CoV in its brief epidemic, our analysis of SARS-CoV-2 genomes shows signs of relaxation of selection. The sequence similarity of the spike receptor binding domain between SARS-CoV-2 and a sequence from pangolin is probably due to an ancient intergenomic introgression. Therefore, SARS-CoV-2 might have cryptically circulated within humans for years before being recently noticed. Data from the early outbreak and hospital archives are needed to trace its evolutionary path and reveal critical steps required for effective spreading. Two mutations, 84S in orf8 protein and 251V in orf3 protein, occurred coincidentally with human intervention. The 84S first appeared on 1/5/2020 and reached a plateau around 1/23/2020, the lockdown of Wuhan. 251V emerged on 1/21/2020 and rapidly increased its frequency. Thus, the roles of these mutations on infectivity need to be elucidated.

Title: Genetic Diversity and Genomic Epidemiology of SARS-COV-2 in Morocco Content: COVID-A9 is an infection disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), declared as a pandemic due to its rapid expansion worldwide. In this study we investigate the genetic diversity and genomic epidemiology of SARS-CoV-2 using 22 virus genome sequences reported by three different laboratories in Morocco till the date 07/06/2020 as well as (40366) virus genomes from all around the world. The SARS-CoV-2 genomes from Moroccan patients revealed 62 mutations of which 30 were missense mutations. The mutations Spike_D614G and NSP12_P323L were present in all the 22 analyzed sequences, followed by N_G204R and N_R203K which occurred in 9 among the 22 sequences. The mutations NSP10_R134S, NSP15_D335N, NSP16_I169L, NSP3_L431H, NSP3_P1292L and Spike_V6F occurred one time in our sequences with no record in other sequence worldwide. These mutations should be investigated to figure out their potential effects on all around the world virulence. Phylogenetic analyses revealed that Moroccan SARS-CoV-2 genomes included 9 viruses pertaining to clade 20A, 9 to clade 20B and 2 to clade 20C. This finding suggest that the epidemic spread in Morocco did not show a predominant SARS-CoV-2 route. For multiple and unrelated introductions of SARS-CoV-2 into Morocco via different routes have occurred, giving rise to the diversity of virus genomes in the country. Furthermore, very likely, the SARS-CoV-2 virus circulated in cryptic way in Morocco starting from the fifteen January before the discovering of the first case the second of March.

Title: Snapshot of the evolution and mutation patterns of SARS-CoV-2 Content: The COVID-19 pandemic is the most important public health threat in recent history. Here we study how its causal agent, SARS-CoV-2, has diversified genetically since its first emergence in December 2019. We have created a pipeline combining both phylogenetic and structural analysis to identify possible human-adaptation related mutations in a data set consisting of 4,894 SARS-CoV-2 complete genome sequences. Although the phylogenetic diversity of SARS-CoV-2 is low, the whole genome phylogenetic tree can be divided into five clusters/clades based on the tree topology and clustering of specific mutations, but its branches exhibit low genetic distance and bootstrap support values. We also identified 11 residues that are high-frequency substitutions, with four of them currently showing some signal for potential positive selection. These fast-evolving sites are in the non-structural proteins nsp2, nsp5 (3CL-protease), nsp6, nsp12 (polymerase) and nsp13 (helicase), in accessory proteins (ORF3a, ORF8) and in the structural proteins N and S. Temporal and spatial analysis of these potentially adaptive mutations revealed that the incidence of some of these sites was declining after having reached an (often local) peak, whereas the frequency of other sites is continually increasing and now exhibit a worldwide distribution. Structural analysis revealed that the mutations are located on the surface of the proteins that modulate biochemical properties. We speculate that this improves binding to cellular proteins and hence represents fine-tuning of adaptation to human cells. Our study has implications for the design of biochemical and clinical experiments to assess whether important properties of SARS-CoV-2 have changed during the epidemic.

Title: The origin and underlying driving forces of the SARS-CoV-2 outbreak Content: BACKGROUND: SARS-CoV-2 began spreading in December 2019 and has since become a pandemic that has impacted many aspects of human society. Several issues concerning the origin, time of introduction to humans, evolutionary patterns, and underlying force driving the SARS-CoV-2 outbreak remain unclear. METHOD: Genetic variation in 137 SARS-CoV-2 genomes and related coronaviruses as of 2/23/2020 was analyzed. RESULT: After correcting for mutational bias, the excess of low frequency mutations on both synonymous and nonsynonymous sites was revealed which is consistent with the recent outbreak of the virus. In contrast to adaptive evolution previously reported for SARS-CoV during its brief epidemic in 2003, our analysis of SARS-CoV-2 genomes shows signs of relaxation. The sequence similarity in the spike receptor binding domain between SARS-CoV-2 and a sequence from pangolin is probably due to an ancient intergenomic introgression that occurred approximately 40 years ago. The current outbreak of SARS-CoV-2 was estimated to have originated on 12/11/2019 (95% HPD 11/13/2019–12/23/2019). The effective population size of the virus showed an approximately 20-fold increase from the onset of the outbreak to the lockdown of Wuhan (1/23/2020) and ceased to increase afterwards, demonstrating the effectiveness of social distancing in preventing its spread. Two mutations, 84S in orf8 protein and 251 V in orf3 protein, occurred coincidentally with human intervention. The former first appeared on 1/5/2020 and plateaued around 1/23/2020. The latter rapidly increased in frequency after 1/23/2020. Thus, the roles of these mutations on infectivity need to be elucidated. Genetic diversity of SARS-CoV-2 collected from China is two times higher than those derived from the rest of the world. A network analysis found that haplotypes collected from Wuhan were interior and had more mutational connections, both of which are consistent with the observation that the SARS-CoV-2 outbreak originated in China. CONCLUSION: SARS-CoV-2 might have cryptically circulated within humans for years before being discovered. Data from the early outbreak and hospital archives are needed to trace its evolutionary path and determine the critical steps required for effective spreading.

Title: The origin and underlying driving forces of the SARS-CoV-2 outbreak Content: BACKGROUND: SARS-CoV-2 began spreading in December 2019 and has since become a pandemic that has impacted many aspects of human society. Several issues concerning the origin, time of introduction to humans, evolutionary patterns, and underlying force driving the SARS-CoV-2 outbreak remain unclear. METHOD: Genetic variation in 137 SARS-CoV-2 genomes and related coronaviruses as of 2/23/2020 was analyzed. RESULT: After correcting for mutational bias, the excess of low frequency mutations on both synonymous and nonsynonymous sites was revealed which is consistent with the recent outbreak of the virus. In contrast to adaptive evolution previously reported for SARS-CoV during its brief epidemic in 2003, our analysis of SARS-CoV-2 genomes shows signs of relaxation. The sequence similarity in the spike receptor binding domain between SARS-CoV-2 and a sequence from pangolin is probably due to an ancient intergenomic introgression that occurred approximately 40 years ago. The current outbreak of SARS-CoV-2 was estimated to have originated on 12/11/2019 (95% HPD 11/13/2019-12/23/2019). The effective population size of the virus showed an approximately 20-fold increase from the onset of the outbreak to the lockdown of Wuhan (1/23/2020) and ceased to increase afterwards, demonstrating the effectiveness of social distancing in preventing its spread. Two mutations, 84S in orf8 protein and 251 V in orf3 protein, occurred coincidentally with human intervention. The former first appeared on 1/5/2020 and plateaued around 1/23/2020. The latter rapidly increased in frequency after 1/23/2020. Thus, the roles of these mutations on infectivity need to be elucidated. Genetic diversity of SARS-CoV-2 collected from China is two times higher than those derived from the rest of the world. A network analysis found that haplotypes collected from Wuhan were interior and had more mutational connections, both of which are consistent with the observation that the SARS-CoV-2 outbreak originated in China. CONCLUSION: SARS-CoV-2 might have cryptically circulated within humans for years before being discovered. Data from the early outbreak and hospital archives are needed to trace its evolutionary path and determine the critical steps required for effective spreading.

Title: Large scale genomic analysis of 3067 SARS-CoV-2 genomes reveals a clonal geo-distribution and a rich genetic variations of hotspots mutations Content: In late December 2019, an emerging viral infection COVID-19 was identified in Wuhan, China, and became a global pandemic. Characterization of the genetic variants of SARS-CoV-2 is crucial in following and evaluating it spread across countries. In this study, we collected and analyzed 3,067 SARS-CoV-2 genomes isolated from 55 countries during the first three months after the onset of this virus. Using comparative genomics analysis, we traced the profiles of the whole-genome mutations and compared the frequency of each mutation in the studied population. The accumulation of mutations during the epidemic period with their geographic locations was also monitored. The results showed 782 variant sites, of which 512 (65.47%) had a non-synonymous effect. Frequencies of mutated alleles revealed the presence of 38 recurrent non-synonymous mutations, including ten hotspot mutations with a prevalence higher than 0.10 in this population and distributed in six SARS-CoV-2 genes. The distribution of these recurrent mutations on the world map revealed certain genotypes specific to the geographic location. We also found co-occurring mutations resulting in the presence of several haplotypes. Moreover, evolution over time has shown a mechanism of mutation co-accumulation which might affect the severity and spread of the SARS-CoV-2. On the other hand, analysis of the selective pressure revealed the presence of negatively selected residues that could be taken into considerations as therapeutic targets We have also created an inclusive unified database (http://genoma.ma/covid-19/) that lists all of the genetic variants of the SARS-CoV-2 genomes found in this study with phylogeographic analysis around the world.

Title: Genome-Wide Identification and Characterization of Point Mutations in the SARS-CoV-2 Genome Content: OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, China, in December 2019 and has been rapidly spreading worldwide. Although the causal relationship among mutations and the features of SARS-CoV-2 such as rapid transmission, pathogenicity, and tropism, remains unclear, our results of genomic mutations in SARS-CoV-2 may help to interpret the interaction between genomic characterization in SARS-CoV-2 and infectivity with the host. METHODS: A total of 4,254 genomic sequences of SARS-CoV-2 were collected from the Global Initiative on Sharing all Influenza Data (GISAID). Multiple sequence alignment for phylogenetic analysis and comparative genomic approach for mutation analysis were conducted using Molecular Evolutionary Genetics Analysis (MEGA), and an in-house program based on Perl language, respectively. RESULTS: Phylogenetic analysis of SARS-CoV-2 strains indicated that there were 3 major clades including S, V, and G, and 2 subclades (G.1 and G.2). There were 767 types of synonymous and 1,352 types of non-synonymous mutation. ORF1a, ORF1b, S, and N genes were detected at high frequency, whereas ORF7b and E genes exhibited low frequency. In the receptor-binding domain (RBD) of the S gene, 11 non-synonymous mutations were observed in the region adjacent to the angiotensin converting enzyme 2 (ACE2) binding site. CONCLUSION: It has been reported that the rapid infectivity and transmission of SARS-CoV-2 associated with host receptor affinity are derived from several mutations in its genes. Without these genetic mutations to enhance evolutionary adaptation, species recognition, host receptor affinity, and pathogenicity, it would not survive. It is expected that our results could provide an important clue in understanding the genomic characteristics of SARS-CoV-2.

Title: Mutations on COVID-19 diagnostic targets Content: Effective, sensitive, and reliable diagnostic reagents are of paramount importance for combating the ongoing coronavirus disease 2019 (COVID-19) pandemic at a time there is no preventive vaccine nor specific drug available for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It would be an absolute tragedy if currently used diagnostic reagents are undermined in any manner. Based on the genotyping of 7818 SARS-CoV-2 genome samples collected up to May 1, 2020, we reveal that essentially all of the current COVID-19 diagnostic targets have had mutations. We further show that SARS-CoV-2 has the most devastating mutations on the targets of various nucleocapsid (N) gene primers and probes, which have been unfortunately used by countries around the world to diagnose COVID-19. Our findings explain what has seriously gone wrong with a specific diagnostic reagent made in China. To understand whether SARS-CoV-2 genes have mutated unevenly, we have computed the mutation ratio and mutation $h$-index of all SARS-CoV genes, indicating that the N gene is the most non-conservative gene in the SARS-CoV-2 genome. Our findings enable researchers to target the most conservative SARS-CoV-2 genes and proteins for the design and development of COVID-19 diagnostic reagents, preventive vaccines, and therapeutic medicines.

Title: Characterizations of SARS-CoV-2 mutational profile, spike protein stability and viral transmission Content: The recent pandemic of SARS-CoV-2 infection has affected more than 3.0 million people worldwide with more than 200 thousand reported deaths. The SARS-CoV-2 genome has a capability of gaining rapid mutations as the virus spreads. Whole genome sequencing data offers a wide range of opportunities to study the mutation dynamics. The advantage of increasing amount of whole genome sequence data of SARS-CoV-2 intrigued us to explore the mutation profile across the genome, to check the genome diversity and to investigate the implications of those mutations in protein stability and viral transmission. Four proteins, surface glycoprotein, nucleocapsid, ORF1ab and ORF8 showed frequent mutations, while envelop, membrane, ORF6 and ORF7a proteins showed conservation in terms of amino acid substitutions. Some of the mutations across different proteins showed co-occurrence, suggesting their functional cooperation in stability, transmission and adaptability. Combined analysis with the frequently mutated residues identified 20 viral variants, among which 12 specific combinations comprised more than 97% of the isolates considered for the analysis. Analysis of protein structure stability of surface glycoprotein mutants indicated viability of specific variants and are more prone to be temporally and spatially distributed across the globe. Similar empirical analysis of other proteins indicated existence of important functional implications of several variants. Analysis of co-occurred mutants indicated their structural and/or functional interaction among different SARS-COV-2 proteins. Identification of frequently mutated variants among COVID-19 patients might be useful for better clinical management, contact tracing and containment of the disease.

Title: Emerging SARS-CoV-2 mutation hot spots include a novel RNA-dependent-RNA polymerase variant Content: BACKGROUND: SARS-CoV-2 is a RNA coronavirus responsible for the pandemic of the Severe Acute Respiratory Syndrome (COVID-19). RNA viruses are characterized by a high mutation rate, up to a million times higher than that of their hosts. Virus mutagenic capability depends upon several factors, including the fidelity of viral enzymes that replicate nucleic acids, as SARS-CoV-2 RNA dependent RNA polymerase (RdRp). Mutation rate drives viral evolution and genome variability, thereby enabling viruses to escape host immunity and to develop drug resistance. METHODS: We analyzed 220 genomic sequences from the GISAID database derived from patients infected by SARS-CoV-2 worldwide from December 2019 to mid-March 2020. SARS-CoV-2 reference genome was obtained from the GenBank database. Genomes alignment was performed using Clustal Omega. Mann-Whitney and Fisher-Exact tests were used to assess statistical significance. RESULTS: We characterized 8 novel recurrent mutations of SARS-CoV-2, located at positions 1397, 2891, 14408, 17746, 17857, 18060, 23403 and 28881. Mutations in 2891, 3036, 14408, 23403 and 28881 positions are predominantly observed in Europe, whereas those located at positions 17746, 17857 and 18060 are exclusively present in North America. We noticed for the first time a silent mutation in RdRp gene in England (UK) on February 9th, 2020 while a different mutation in RdRp changing its amino acid composition emerged on February 20th, 2020 in Italy (Lombardy). Viruses with RdRp mutation have a median of 3 point mutations [range: 2-5], otherwise they have a median of 1 mutation [range: 0-3] (p value < 0.001). CONCLUSIONS: These findings suggest that the virus is evolving and European, North American and Asian strains might coexist, each of them characterized by a different mutation pattern. The contribution of the mutated RdRp to this phenomenon needs to be investigated. To date, several drugs targeting RdRp enzymes are being employed for SARS-CoV-2 infection treatment. Some of them have a predicted binding moiety in a SARS-CoV-2 RdRp hydrophobic cleft, which is adjacent to the 14408 mutation we identified. Consequently, it is important to study and characterize SARS-CoV-2 RdRp mutation in order to assess possible drug-resistance viral phenotypes. It is also important to recognize whether the presence of some mutations might correlate with different SARS-CoV-2 mortality rates.

Title: Emerging SARS-CoV-2 mutation hot spots include a novel RNA-dependent-RNA polymerase variant Content: BACKGROUND: SARS-CoV-2 is a RNA coronavirus responsible for the pandemic of the Severe Acute Respiratory Syndrome (COVID-19). RNA viruses are characterized by a high mutation rate, up to a million times higher than that of their hosts. Virus mutagenic capability depends upon several factors, including the fidelity of viral enzymes that replicate nucleic acids, as SARS-CoV-2 RNA dependent RNA polymerase (RdRp). Mutation rate drives viral evolution and genome variability, thereby enabling viruses to escape host immunity and to develop drug resistance. METHODS: We analyzed 220 genomic sequences from the GISAID database derived from patients infected by SARS-CoV-2 worldwide from December 2019 to mid-March 2020. SARS-CoV-2 reference genome was obtained from the GenBank database. Genomes alignment was performed using Clustal Omega. Mann–Whitney and Fisher-Exact tests were used to assess statistical significance. RESULTS: We characterized 8 novel recurrent mutations of SARS-CoV-2, located at positions 1397, 2891, 14408, 17746, 17857, 18060, 23403 and 28881. Mutations in 2891, 3036, 14408, 23403 and 28881 positions are predominantly observed in Europe, whereas those located at positions 17746, 17857 and 18060 are exclusively present in North America. We noticed for the first time a silent mutation in RdRp gene in England (UK) on February 9th, 2020 while a different mutation in RdRp changing its amino acid composition emerged on February 20th, 2020 in Italy (Lombardy). Viruses with RdRp mutation have a median of 3 point mutations [range: 2–5], otherwise they have a median of 1 mutation [range: 0–3] (p value < 0.001). CONCLUSIONS: These findings suggest that the virus is evolving and European, North American and Asian strains might coexist, each of them characterized by a different mutation pattern. The contribution of the mutated RdRp to this phenomenon needs to be investigated. To date, several drugs targeting RdRp enzymes are being employed for SARS-CoV-2 infection treatment. Some of them have a predicted binding moiety in a SARS-CoV-2 RdRp hydrophobic cleft, which is adjacent to the 14408 mutation we identified. Consequently, it is important to study and characterize SARS-CoV-2 RdRp mutation in order to assess possible drug-resistance viral phenotypes. It is also important to recognize whether the presence of some mutations might correlate with different SARS-CoV-2 mortality rates.

Title: MicroGMT: A Mutation Tracker for SARS-CoV-2 and Other Microbial Genome Sequences Content: With the continued spread of SARS-CoV-2 virus around the world, researchers often need to quickly identify novel mutations in newly sequenced SARS-CoV-2 genomes for studying the molecular evolution and epidemiology of the virus. We have developed a Python package, MicroGMT, which takes either raw sequence reads or assembled genome sequences as input and compares against database sequences to identify and characterize indels and point mutations. Although our default setting is optimized for SARS-CoV-2 virus, the package can be also applied to any other microbial genomes. The software is freely available at Github URL https://github.com/qunfengdong/MicroGMT.

Title: Emergence of genomic diversity and recurrent mutations in SARS-CoV-2 Content: Abstract SARS-CoV-2 is a SARS-like coronavirus of likely zoonotic origin first identified in December 2019 in Wuhan, the capital of China's Hubei province. The virus has since spread globally, resulting in the currently ongoing COVID-19 pandemic. The first whole genome sequence was published on January 52,020, and thousands of genomes have been sequenced since this date. This resource allows unprecedented insights into the past demography of SARS-CoV-2 but also monitoring of how the virus is adapting to its novel human host, providing information to direct drug and vaccine design. We curated a dataset of 7666 public genome assemblies and analysed the emergence of genomic diversity over time. Our results are in line with previous estimates and point to all sequences sharing a common ancestor towards the end of 2019, supporting this as the period when SARS-CoV-2 jumped into its human host. Due to extensive transmission, the genetic diversity of the virus in several countries recapitulates a large fraction of its worldwide genetic diversity. We identify regions of the SARS-CoV-2 genome that have remained largely invariant to date, and others that have already accumulated diversity. By focusing on mutations which have emerged independently multiple times (homoplasies), we identify 198 filtered recurrent mutations in the SARS-CoV-2 genome. Nearly 80% of the recurrent mutations produced non-synonymous changes at the protein level, suggesting possible ongoing adaptation of SARS-CoV-2. Three sites in Orf1ab in the regions encoding Nsp6, Nsp11, Nsp13, and one in the Spike protein are characterised by a particularly large number of recurrent mutations (>15 events) which may signpost convergent evolution and are of particular interest in the context of adaptation of SARS-CoV-2 to the human host. We additionally provide an interactive user-friendly web-application to query the alignment of the 7666 SARS-CoV-2 genomes.

Title: Emergence of genomic diversity and recurrent mutations in SARS-CoV-2 Content: SARS-CoV-2 is a SARS-like coronavirus of likely zoonotic origin first identified in December 2019 in Wuhan, the capital of China's Hubei province. The virus has since spread globally, resulting in the currently ongoing COVID-19 pandemic. The first whole genome sequence was published on January 5 2020, and thousands of genomes have been sequenced since this date. This resource allows unprecedented insights into the past demography of SARS-CoV-2 but also monitoring of how the virus is adapting to its novel human host, providing information to direct drug and vaccine design. We curated a dataset of 7666 public genome assemblies and analysed the emergence of genomic diversity over time. Our results are in line with previous estimates and point to all sequences sharing a common ancestor towards the end of 2019, supporting this as the period when SARS-CoV-2 jumped into its human host. Due to extensive transmission, the genetic diversity of the virus in several countries recapitulates a large fraction of its worldwide genetic diversity. We identify regions of the SARS-CoV-2 genome that have remained largely invariant to date, and others that have already accumulated diversity. By focusing on mutations which have emerged independently multiple times (homoplasies), we identify 198 filtered recurrent mutations in the SARS-CoV-2 genome. Nearly 80% of the recurrent mutations produced non-synonymous changes at the protein level, suggesting possible ongoing adaptation of SARS-CoV-2. Three sites in Orf1ab in the regions encoding Nsp6, Nsp11, Nsp13, and one in the Spike protein are characterised by a particularly large number of recurrent mutations (>15 events) which may signpost convergent evolution and are of particular interest in the context of adaptation of SARS-CoV-2 to the human host. We additionally provide an interactive user-friendly web-application to query the alignment of the 7666 SARS-CoV-2 genomes.

Title: Analysis of the mutation dynamics of SARS-CoV-2 reveals the spread history and emergence of RBD mutant with lower ACE2 binding affinity Content: Monitoring the mutation dynamics of SARS-CoV-2 is critical for the development of effective approaches to contain the pathogen. By analyzing 106 SARS-CoV-2 and 39 SARS genome sequences, we provided direct genetic evidence that SARS-CoV-2 has a much lower mutation rate than SARS. Minimum Evolution phylogeny analysis revealed the putative original status of SARS-CoV-2 and the early-stage spread history. The discrepant phylogenies for the spike protein and its receptor binding domain proved a previously reported structural rearrangement prior to the emergence of SARS-CoV-2. Despite that we found the spike glycoprotein of SARS-CoV-2 is particularly more conserved, we identified a mutation that leads to weaker receptor binding capability, which concerns a SARS-CoV-2 sample collected on 27th January 2020 from India. This represents the first report of a significant SARS-CoV-2 mutant, and raises the alarm that the ongoing vaccine development may become futile in future epidemic if more mutations were identified. Highlights Based on the currently available genome sequence data, we proved that SARS-COV-2 genome has a much lower mutation rate and genetic diversity than SARS during the 2002-2003 outbreak. The spike (S) protein encoding gene of SARS-COV-2 is found relatively more conserved than other protein-encoding genes, which is a good indication for the ongoing antiviral drug and vaccine development. Minimum Evolution phylogeny analysis revealed the putative original status of SARS-CoV-2 and the early-stage spread history. We confirmed a previously reported rearrangement in the S protein arrangement of SARS-COV-2, and propose that this rearrangement should have occurred between human SARS-CoV and a bat SARS-CoV, at a time point much earlier before SARS-COV-2 transmission to human. We provided first evidence that a mutated SARS-COV-2 with reduced human ACE2 receptor binding affinity have emerged in India based on a sample collected on 27th January 2020.

Title: Evolutionary analysis of SARS-CoV-2: how mutation of Non-Structural Protein 6 (NSP6) could affect viral autophagy Content: BACKGROUND: SARS-CoV-2 is a new coronavirus that has spread globally, infecting more than 150000 people, and being declared pandemic by the WHO. We provide here bio-informatic, evolutionary analysis of 351 available sequences of its genome with the aim of mapping genome structural variations and the patterns of selection. METHODS: A Maximum likelihood tree has been built and selective pressure has been investigated in order to find any mutation developed during the SARS-CoV-2 epidemic that could potentially affect clinical evolution of the infection. FINDING: We have found in more recent isolates the presence of two mutations affecting the Non-Structural Protein 6 (NSP6) and the Open Reding Frame10 (ORF 10) adjacent regions. Amino acidic change stability analysis suggests both mutations could confer lower stability of the protein structures. INTERPRETATION: One of the two mutations, likely developed within the genome during virus spread, could affect virus intracellular survival. Genome follow-up of SARS-CoV-2 spread is urgently needed in order to identify mutations that could significantly modify virus pathogenicity.

Title: Mutation density changes in SARS-CoV-2 are related to the pandemic stage but to a lesser extent in the dominant strain with mutations in spike and RdRp Content: Since its emergence in Wuhan, China in late 2019, the origin and evolution of SARS-CoV-2 have been among the most debated issues related to COVID-19. Throughout its spread around the world, the viral genome continued acquiring new mutations and some of them became widespread. Among them, 14408 C>T and 23403 A>G mutations in RdRp and S, respectively, became dominant in Europe and the US, which led to debates regarding their effects on the mutability and transmissibility of the virus. In this study, we aimed to investigate possible differences between time-dependent variation of mutation densities (MDe) of viral strains that carry these two mutations and those that do not. Our analyses at the genome and gene level led to two important findings: First, time-dependent changes in the average MDe of circulating SARS-CoV-2 genomes showed different characteristics before and after the beginning of April, when daily new case numbers started levelling off. Second, this pattern was much delayed or even non-existent for the “mutant” (MT) strain that harbored both 14408 C>T and 23403 A>G mutations. Although these differences were not limited to a few hotspots, it is intriguing that the MDe increase is most evident in two critical genes, S and Orf1ab, which are also the genes that harbor the defining mutations of the MT genotype. The nature of these unexpected relationships warrant further research.

Title: Evolutionary analysis of SARS-CoV-2: how mutation of Non-Structural Protein 6 (NSP6) could affect viral autophagy Content: Abstract Background SARS-CoV-2 is a new coronavirus that has spread globally, infecting more than 150000 people, and being declared pandemic by the WHO. We provide here bio-informatic, evolutionary analysis of 351 available sequences of its genome with the aim of mapping genome structural variations and the patterns of selection. Methods A Maximum likelihood tree has been built and selective pressure has been investigated in order to find any mutation developed during the SARS-CoV-2 epidemic that could potentially affect clinical evolution of the infection. Finding We have found in more recent isolates the presence of two mutations affecting the Non-Structural Protein 6 (NSP6) and the Open Reding Frame10 (ORF 10) adjacent regions. Amino acidic change stability analysis suggests both mutations could confer lower stability of the protein structures. Interpretation One of the two mutations, likely developed within the genome during virus spread, could affect virus intracellular survival. Genome follow-up of SARS-CoV-2 spread is urgently needed in order to identify mutations that could significantly modify virus pathogenicity.

Title: Mutational Signatures and Heterogeneous Host Response Revealed Via Large-Scale Characterization of SARS-COV-2 Genomic Diversity Content: To dissect the mechanisms underlying the observed inflation of variants in SARS-CoV-2 genome, we present the largest up-to-date analysis of intra-host genomic diversity, which reveals that the majority of samples present a complex sublineage architecture, due to the interplay between host-related mutational processes and transmission dynamics. Strikingly, the deconvolution of the entire set of intra-host variants reveals the existence of mutually exclusive viral mutational signatures, which prove that distinct hosts differently respond to SARS-CoV-2 infections. In particular, two signatures are likely ruled by APOBEC and Reactive Oxygen Species (ROS), which induce hypermutation in a significant number of samples, and appear to be affected by severe purifying selection. Conversely, several mutations linked to low-rate mutational processes appear to transit to clonality in the population, eventually leading to the definition of new viral genotypes and to an increase of overall genomic diversity. Finally, we demonstrate that a high number of variants are observed in samples associated to independent lineages, likely due to signature-related mutational hotspots or to positive selection.

Title: SARS-CoV-2 mutations altering regulatory properties: deciphering host’s and virus’s perspectives Content: Since the first recorded case of the SARS-CoV-2, it has acquired several mutations in its genome while spreading throughout the globe. However, apart from some changes in protein coding, functional importance of these mutations in disease pathophysiology are still largely unknown. In this study, we investigated the significance of these mutations both from the host’s and virus’s perspective by analyzing the host miRNA binding and virus’s internal ribosome entry site (IRES), respectively. Strikingly, we observed that due to the acquired mutations, host miRNAs bind differently compared to the reference; where few of the miRNAs lost and few gained the binding affinity for targeting the viral genome. Moreover, functional enrichment analysis suggests that targets of both of these gained and lost miRNAs might be involved in various host immune signaling pathways. Also, we sought to shed some insights on the impacts of mutations on the IRES structure of SARS-CoV-2. Remarkably, we detected that three particular mutations in the IRES can disrupt its secondary structure which can further make the virus less functional. These results could be valuable in exploring the functional importance of the mutations of SARS-CoV-2 and could provide novel insights into the differences observed different parts of the world.

Title: Identification of novel mutations in RNA-dependent RNA polymerases of SARS-CoV-2 and their implications on its protein structure Content: The rapid development of SARS-CoV-2 mediated COVID-19 pandemic has been the cause of significant health concern, highlighting the immediate need for the effective antivirals. SARS-CoV-2 is an RNA virus that has an inherent high mutation rate. These mutations drive viral evolution and genome variability, thereby, facilitating viruses to have rapid antigenic shifting to evade host immunity and to develop drug resistance. Viral RNA-dependent RNA polymerases (RdRp) perform viral genome duplication and RNA synthesis. Therefore, we compared the available RdRp sequences of SARS-CoV-2 from Indian isolates and ‘Wuhan wet sea food market virus’ sequence to identify, if any, variation between them. We report seven mutations observed in Indian SARS-CoV-2 isolates and three unique mutations that showed changes in the secondary structure of the RdRp protein at region of mutation. We also studied molecular dynamics using normal mode analyses and found that these mutations alter the stability of RdRp protein. Therefore, we propose that RdRp mutations in Indian SARS-CoV-2 isolates might have functional consequences that can interfere with RdRp targeting pharmacological agents.

Title: Stability of SARS-CoV-2 Phylogenies Content: The SARS-CoV-2 pandemic has led to unprecedented, nearly real-time genetic tracing due to the rapid community sequencing response. Researchers immediately leveraged these data to infer the evolutionary relationships among viral samples and to study key biological questions, including whether host viral genome editing and recombination are features of SARS-CoV-2 evolution. This global sequencing effort is inherently decentralized and must rely on data collected by many labs using a wide variety of molecular and bioinformatic techniques. There is thus a strong possibility that systematic errors associated with lab-specific practices affect some sequences in the repositories. We find that some recurrent mutations in reported SARS-CoV-2 genome sequences have been observed predominantly or exclusively by single labs, co-localize with commonly used primer binding sites and are more likely to affect the protein coding sequences than other similarly recurrent mutations. We show that their inclusion can affect phylogenetic inference on scales relevant to local lineage tracing, and make it appear as though there has been an excess of recurrent mutation and/or recombination among viral lineages. We suggest how samples can be screened and problematic mutations removed. We also develop tools for comparing and visualizing differences among phylogenies and we show that consistent clade- and tree-based comparisons can be made between phylogenies produced by different groups. These will facilitate evolutionary inferences and comparisons among phylogenies produced for a wide array of purposes. Building on the SARS-CoV-2 Genome Browser at UCSC, we present a toolkit to compare, analyze and combine SARS-CoV-2 phylogenies, find and remove potential sequencing errors and establish a widely shared, stable clade structure for a more accurate scientific inference and discourse. Foreword We wish to thank all groups that responded rapidly by producing these invaluable and essential sequence data. Their contributions have enabled an unprecedented, lightning-fast process of scientific discovery---truly an incredible benefit for humanity and for the scientific community. We emphasize that most lab groups with whom we associate specific suspicious alleles are also those who have produced the most sequence data at a time when it was urgently needed. We commend their efforts. We have already contacted each group and many have updated their sequences. Our goal with this work is not to highlight potential errors, but to understand the impacts of these and other kinds of highly recurrent mutations so as to identify commonalities among the suspicious examples that can improve sequence quality and analysis going forward.

Title: Genetic analysis of SARS-CoV-2 strains collected from North Africa: viral origins and mutational spectrum Content: In Morocco two waves of SARS-CoV-2 infections have been recorded. The first one occurred from March 02, 2020 with infections mostly imported from Europe and the second one dominated by local infections. At the time of writing, the genetic diversity of Moroccan isolates of SARS-CoV-2 has not yet been reported. The present study aimed to analyze first the genomic variation of the twenty-eight Moroccan strains of SARS-CoV-2 isolated from March 03, 2020 to May 15, 2020, to compare their distributions with twelve other viral genomes from North Africa as well as to identify their possible sources. Our finding revealed 61 mutations in the Moroccan genomes of SARS-CoV-2 compared to the reference sequence Wuhan-Hu-1/2019, of them 23 (37.7%) were present in two or more genomes. Focusing on non-synonymous mutations, 29 (47.54%) were distributed in five genes (ORF1ab, spike, membrane, nucleocapsid and ORF3a) with variable frequencies. The non-structural protein coding regions nsp3-Multi domain and nsp12-RdRp of the ORF1ab gene harbored more mutations, with six for each. The comparison of genetic variants of fourty North African strains revealed that two non-synonymous mutations D614G (in spike) and Q57H (in ORF3a) were common in four countries (Morocco, Tunisia, Algeria and Egypt), with a prevalence of 92.5% (n = 37) and 42.5% (n = 17), respectively, of the total genomes. Phylogenetic analysis showed that the Moroccan and Tunisian SARS-CoV-2 strains were closely related to those from different origins (Asia, Europe, North and South America) and distributed in different distinct subclades. This could indicate different sources of infection with no specific strain dominating yet in in these countries. These results have the potential to lead to new comprehensive investigations combining genomic data, epidemiological information and the clinical characteristics of patients with SARS-CoV-2.

Title: Genome analysis of SARS-CoV-2 isolates occurring in India: Present scenario Content: Background: The origin of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still a debatable topic. The association of the virus spread from the market is supported by the close relation of genome sequences of environmental surface samples with virus samples from earliest patients by phylogenetic analysis. Objectives: To have an insight into the SARS-CoV-2 genome sequences reported from India for better understanding on their epidemiology and virulence. Methods: Genome sequences of Indian isolates of SARS-CoV-2 were analyzed to understand their phylogeny and divergence with respect to other isolates reported from other countries. Amino acid sequences of individual open reading frames (ORFs) from SARS-CoV-2 Indian isolates were aligned with sequences of isolates reported from other countries to identify the mutations occurred in Indian isolates. Results: Our analysis suggests that Indian SARS-CoV-2 isolates are closely related to isolates reported from other parts of the world. Most ORFs are highly conserved; mutations were also detected in some ORFs. We found that most isolates reported from India have key mutations at 614th position of the S protein and 84th position of the ORF 8, which has been reported to be associated with high virulence and high transmission rate. Conclusion: An attempt was made to understand the SARS-CoV-2 virus reported from India. SARS-CoV-2 reported from India was closely similar to other SARS-CoV-2 reported from other parts of the world, which suggests that vaccines and other therapeutic methods generated from other countries might work well in India. In addition, available sequence data suggest that majority of Indian isolates are capable of high transmission and virulence.

Title: Genome analysis of SARS-CoV-2 isolates occurring in India: Present scenario. Content: Background The origin of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is still a debatable topic. The association of the virus spread from the market is supported by the close relation of genome sequences of environmental surface samples with virus samples from earliest patients by phylogenetic analysis. Objectives To have an insight into the SARS-CoV-2 genome sequences reported from India for better understanding on their epidemiology and virulence. Methods Genome sequences of Indian isolates of SARS-CoV-2 were analyzed to understand their phylogeny and divergence with respect to other isolates reported from other countries. Amino acid sequences of individual open reading frames (ORFs) from SARS-CoV-2 Indian isolates were aligned with sequences of isolates reported from other countries to identify the mutations occurred in Indian isolates. Results Our analysis suggests that Indian SARS-CoV-2 isolates are closely related to isolates reported from other parts of the world. Most ORFs are highly conserved; mutations were also detected in some ORFs. We found that most isolates reported from India have key mutations at 614th position of the S protein and 84th position of the ORF 8, which has been reported to be associated with high virulence and high transmission rate. Conclusion An attempt was made to understand the SARS-CoV-2 virus reported from India. SARS-CoV-2 reported from India was closely similar to other SARS-CoV-2 reported from other parts of the world, which suggests that vaccines and other therapeutic methods generated from other countries might work well in India. In addition, available sequence data suggest that majority of Indian isolates are capable of high transmission and virulence.

Title: Conserved Genomic Terminals of SARS-CoV-2 as Co-evolving Functional Elements and Potential Therapeutic Targets Content: To identify features in the genome of the SARS-CoV-2 pathogen responsible for the COVID-19 pandemic that may contribute to its viral replication, host pathogenicity, and vulnerabilities, we investigated how and to what extent the SARS-CoV-2 genome sequence differs from other well-characterized human and animal coronavirus genomes. Our analyses suggest the presence of unique sequence signatures in the 3’-untranslated region (UTR) of betacoronavirus lineage B, which phylogenetically encompasses SARS-CoV-2, SARS-CoV, as well as multiple groups of bat and animal coronaviruses. In addition, we identified genome-wide patterns of variation across different SARS-CoV-2 strains that likely reflect the effects of selection. Finally, we provide evidence for a possible host microRNA-mediated interaction between the 3’-UTR and human microRNA hsa-miR-1307-3p based on predicted, yet extensive, complementary base-pairings and similar interactions involving the Influenza A H1N1 virus. This interaction also suggests a possible survival mechanism, whereby a mutation in the SARS-CoV-2 3’-UTR leads to a weakened host immune response. The potential roles of host microRNAs in SARS-CoV-2 replication and infection, and the exploitation of conserved features in the 3’-UTR as therapeutic targets warrant further investigation.

Title: Naturally mutated spike proteins of SARS-CoV-2 variants show differential levels of cell entry Content: The causative agent of the coronavirus disease 2019 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is steadily mutating during continuous transmission among humans. Such mutations can occur in the spike (S) protein that binds to the angiotensin-converting enzyme-2 (ACE2) receptor and is cleaved by transmembrane protease serine 2 (TMPRSS2). However, whether S mutations affect SARS-CoV-2 infectivity remains unknown. Here, we show that naturally occurring S mutations can reduce or enhance cell entry via ACE2 and TMPRSS2. A SARS-CoV-2 S-pseudotyped lentivirus exhibits substantially lower entry than SARS-CoV S. Among S variants, the D614G mutant shows the highest cell entry, as supported by structural observations. Nevertheless, the D614G mutant remains susceptible to neutralization by antisera against prototypic viruses. Taken together, these data indicate that the D614G mutation enhances viral infectivity while maintaining neutralization susceptibility.

Title: Mega-phylogeny sheds light on SARS-CoV-2 spatial phylogenetic structure Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emergent RNA virus that spread around the planet in about 4 months. The consequences of this rapid spread on the virus evolution are under investigation. In this work, we analyzed ca. 9,000 SARS-CoV-2 genomes from Africa, America, Asia, Europe, and Oceania. We show that the virus is a complex of slightly different genetic variants that are unevenly distributed on Earth. Furthermore, we demonstrate that SARS-CoV-2 phylogeny is spatially structured. We hypothesize this could be the result of founder effects occurring as a consequence of, and local evolution occurring after, long-distance dispersal. In light of our results, we discuss how dispersal may constitute an opportunity for the virus to fix otherwise rare, and/or develop new, mutations. Based on previous studies, the possibility that this could significantly affect the virus phenotype is not remote. Relevance A cluster of pneumonia cases of unknown etiology was reported in December 2019 in Wuhan, Hubei province, China. Since then, hundreds of thousands of people have died all around the planet. Quickly after the pandemic onset, metagenomic studies showed the causative agent, now named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belonged to the Betacoronavirus genus, responsible for spillover events in 2002 and 2012 (severe acute respiratory syndrome and Middle East respiratory syndrome, respectively). The zoonotic origins of these viruses (possibly bats, camelids, pangolins and/or palm civets) have received much attention. However, other evolutionary aspects, such as spatial variation, have received comparatively little attention. This study shows that SARS-CoV-2 variants, which we call virotypes, are heterogeneously distributed on Earth and demonstrates that the virus phylogeny is geographically structured. We explain how this may be due to founder effects combined with high mutation rates.

Title: Genomic, geographic and temporal distributions of SARS-CoV-2 mutations Content: The COVID-19 pandemic is the most significant public health issue in recent history. Its causal agent, SARS-CoV-2, has evolved rapidly since its first emergence in December 2019. Mutations in the viral genome have critical impacts on the adaptation of viral strains to the local environment, and may alter the characteristics of viral transmission, disease manifestation, and the efficacy of treatment and vaccination. Using the complete sequences of 1,932 SARS-CoV-2 genomes, we examined the genomic, geographic and temporal distributions of aged, new, and frequent mutations of SARS-CoV-2, and identified six phylogenetic clusters of the strains, which also exhibit a geographic preference in different continents. Mutations in the form of single nucleotide variations (SNVs) provide a direct interpretation for the six phylogenetic clusters. Linkage disequilibrium, haplotype structure, evolutionary process, global distribution of mutations unveiled a sketch of the mutational history. Additionally, we found a positive correlation between the average mutation count and case fatality, and this correlation had strengthened with time, suggesting an important role of SNVs on disease outcomes. This study suggests that SNVs may become an important consideration in virus detection, clinical treatment, drug design, and vaccine development to avoid target shifting, and that continued isolation and sequencing is a crucial component in the fight against this pandemic. Significance Statement Mutation is the driving force of evolution for viruses like SARS-CoV-2, the causal agent of COVID-19. In this study, we discovered that the genome of SARS-CoV-2 is changing rapidly from the originally isolated form. These mutations have been spreading around the world and caused more than 2.5 million of infected cases and 170 thousands of deaths. We found that fourteen frequent mutations identified in this study can characterize the six main clusters of SARS-CoV-2 strains. In addition, we found the mutation burden is positively correlated with the fatality of COVID-19 patients. Understanding mutations in the SARS-CoV-2 genome will provide useful insight for the design of treatment and vaccination.

Title: Mutations in SARS-CoV-2 viral RNA identified in Eastern India: Possible implications for the ongoing outbreak in India and impact on viral structure and host susceptibility. Content: Direct massively parallel sequencing of SARS-CoV-2 genome was undertaken from nasopharyngeal and oropharyngeal swab samples of infected individuals in Eastern India. Seven of the isolates belonged to the A2a clade, while one belonged to the B4 clade. Specific mutations, characteristic of the A2a clade, were also detected, which included the P323L in RNA-dependent RNA polymerase and D614G in the Spike glycoprotein. Further, our data revealed emergence of novel subclones harbouring nonsynonymous mutations, viz. G1124V in Spike (S) protein, R203K, and G204R in the nucleocapsid (N) protein. The N protein mutations reside in the SR-rich region involved in viral capsid formation and the S protein mutation is in the S2 domain, which is involved in triggering viral fusion with the host cell membrane. Interesting correlation was observed between these mutations and travel or contact history of COVID-19 positive cases. Consequent alterations of miRNA binding and structure were also predicted for these mutations. More importantly, the possible implications of mutation D614G (in SD domain) and G1124V (in S2 subunit) on the structural stability of S protein have also been discussed. Results report for the first time a bird's eye view on the accumulation of mutations in SARS-CoV-2 genome in Eastern India.

Title: Genomic diversity and hotspot mutations in 30,983 SARS-CoV-2 genomes: moving toward a universal vaccine for the “confined virus”? Content: The Coronavirus disease 19 (COVID-19) pandemic has been ongoing since its onset in late November 2019 in Wuhan, China. To date, the SARS-CoV-2 virus has infected more than 8 million people worldwide and killed over 5% of them. Efforts are being made all over the world to control the spread of the disease and most importantly to develop a vaccine. Understanding the genetic evolution of the virus, its geographic characteristics and stability is particularly important for developing a universal vaccine covering all circulating strains of SARS-CoV-2 and for predicting its efficacy. In this perspective, we analyzed the sequences of 30,983 complete genomes from 80 countries located in six geographical zones (Africa, Asia, Europe, North & South America, and Oceania) isolated from December 24, 2019 to May 13, 2020, and compared them to the reference genome. Our in-depth analysis revealed the presence of 3,206 variant sites compared to the reference Wuhan-Hu-1 genome, with a distribution that is largely uniform over all continents. Remarkably, a low frequency of recurrent mutations was observed; only 182 mutations (5.67%) had a prevalence greater than 1%. Nevertheless, fourteen hotspot mutations (> 10%) were identified at different locations, seven at the ORF1ab gene (in regions coding for nsp2, nsp3, nsp6, nsp12, nsp13, nsp14 and nsp15), three in the nucleocapsid protein, one in the spike protein, one in orf3a, and one in orf8. Moreover, 35 non-synonymous mutations were identified in the receptor-binding domain (RBD) of the spike protein with a low prevalence (<1%) across all genomes, of which only four could potentially enhance the binding of the SARS-CoV-2 spike protein to the human receptor ACE2. These results along with the phylogenetic analysis demonstrate that the virus does not have a significant divergence at the protein level compared to the reference both among and within different geographical areas. Unlike the influenza virus or HIV viruses, the slow rate of mutation of SARS-CoV-2 makes the potential of developing an effective global vaccine very likely.

Title: Genetic analysis of SARS-CoV-2 isolates collected from Bangladesh: insights into the origin, mutation spectrum, and possible pathomechanism Content: As the coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), rages across the world, killing hundreds of thousands and infecting millions, researchers are racing against time to elucidate the viral genome. Some Bangladeshi institutes are also in this race, sequenced a few isolates of the virus collected from Bangladesh. Here, we present a genomic analysis of 14 isolates. The analysis revealed that SARS-CoV-2 isolates sequenced from Dhaka and Chittagong were the lineage of Europe and the Middle East, respectively. Our analysis identified a total of 42 mutations, including three large deletions, half of which were synonymous. Most of the missense mutations in Bangladeshi isolates found to have weak effects on the pathogenesis. Some mutations may lead the virus to be less pathogenic than the other countries. Molecular docking analysis to evaluate the effect of the mutations on the interaction between the viral spike proteins and the human ACE2 receptor, though no significant interaction was observed. This study provides some preliminary insights into the origin of Bangladeshi SARS-CoV-2 isolates, mutation spectrum and its possible pathomechanism, which may give an essential clue for designing therapeutics and management of COVID-19 in Bangladesh.

Title: Infidelity of SARS-CoV Nsp14-Exonuclease Mutant Virus Replication Is Revealed by Complete Genome Sequencing Content: Most RNA viruses lack the mechanisms to recognize and correct mutations that arise during genome replication, resulting in quasispecies diversity that is required for pathogenesis and adaptation. However, it is not known how viruses encoding large viral RNA genomes such as the Coronaviridae (26 to 32 kb) balance the requirements for genome stability and quasispecies diversity. Further, the limits of replication infidelity during replication of large RNA genomes and how decreased fidelity impacts virus fitness over time are not known. Our previous work demonstrated that genetic inactivation of the coronavirus exoribonuclease (ExoN) in nonstructural protein 14 (nsp14) of murine hepatitis virus results in a 15-fold decrease in replication fidelity. However, it is not known whether nsp14-ExoN is required for replication fidelity of all coronaviruses, nor the impact of decreased fidelity on genome diversity and fitness during replication and passage. We report here the engineering and recovery of nsp14-ExoN mutant viruses of severe acute respiratory syndrome coronavirus (SARS-CoV) that have stable growth defects and demonstrate a 21-fold increase in mutation frequency during replication in culture. Analysis of complete genome sequences from SARS-ExoN mutant viral clones revealed unique mutation sets in every genome examined from the same round of replication and a total of 100 unique mutations across the genome. Using novel bioinformatic tools and deep sequencing across the full-length genome following 10 population passages in vitro, we demonstrate retention of ExoN mutations and continued increased diversity and mutational load compared to wild-type SARS-CoV. The results define a novel genetic and bioinformatics model for introduction and identification of multi-allelic mutations in replication competent viruses that will be powerful tools for testing the effects of decreased fidelity and increased quasispecies diversity on viral replication, pathogenesis, and evolution.

Title: Mutations in SARS-CoV-2 viral RNA identified in Eastern India: Possible implications for the ongoing outbreak in India and impact on viral structure and host susceptibility Content: Direct massively parallel sequencing of SARS-CoV-2 genome was undertaken from nasopharyngeal and oropharyngeal swab samples of infected individuals in Eastern India. Seven of the isolates belonged to the A2a clade, while one belonged to the B4 clade. Specific mutations, characteristic of the A2a clade, were also detected, which included the P323L in RNA-dependent RNA polymerase and D614G in the Spike glycoprotein. Further, our data revealed emergence of novel subclones harbouring nonsynonymous mutations, viz. G1124V in Spike (S) protein, R203K, and G204R in the nucleocapsid (N) protein. The N protein mutations reside in the SR-rich region involved in viral capsid formation and the S protein mutation is in the S(2) domain, which is involved in triggering viral fusion with the host cell membrane. Interesting correlation was observed between these mutations and travel or contact history of COVID-19 positive cases. Consequent alterations of miRNA binding and structure were also predicted for these mutations. More importantly, the possible implications of mutation D614G (in S(D) domain) and G1124V (in S(2) subunit) on the structural stability of S protein have also been discussed. Results report for the first time a bird’s eye view on the accumulation of mutations in SARS-CoV-2 genome in Eastern India. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12038-020-00046-1) contains supplementary material, which is available to authorized users.

Title: A comparative analysis for SARS-CoV-2 Content: COVID-19 has affected the world tremendously. It is critical that biological experiments and clinical designs are informed by computational approaches for time- and cost-effective solutions. Comparative analyses particularly can play a key role to reveal structural changes in proteins due to mutations, which can lead to behavioural changes, such as the increased binding of the SARS-CoV-2 surface glycoprotein to human ACE2 receptors. The aim of this report is to provide an easy to follow tutorial for biologists and others without delving into different bioinformatics tools. More complex analyses such as the use of large-scale computational methods can then be utilised. Starting with a SARS-CoV-2 genome sequence, the report shows visualising DNA sequence features, deriving amino acid sequences, and aligning different genomes to analyse mutations and differences. The report provides further insights into how the SARS-CoV-2 surface glycoprotein mutated for higher binding affinity to human ACE2 receptors, compared to the SARS-CoV protein, by integrating existing 3D protein models.

Title: Characterizations of SARS-CoV-2 mutational profile, spike protein stability and viral transmission Content: The recent pandemic of SARS-CoV-2 infection has affected more than 3.0 million people worldwide with more than 200 thousand reported deaths. The SARS-CoV-2 genome has the capability of gaining rapid mutations as the virus spreads. Whole-genome sequencing data offers a wide range of opportunities to study mutation dynamics. The advantage of an increasing amount of whole-genome sequence data of SARS-CoV-2 intrigued us to explore the mutation profile across the genome, to check the genome diversity, and to investigate the implications of those mutations in protein stability and viral transmission. We have identified frequently mutated residues by aligning ~660 SARS-CoV-2 genomes and validated in 10,000 datasets available in GISAID Nextstrain. We further evaluated the potential of these frequently mutated residues in protein structure stability of spike glycoprotein and their possible functional consequences in other proteins. Among the 11 genes, surface glycoprotein, nucleocapsid, ORF1ab, and ORF8 showed frequent mutations, while envelop, membrane, ORF6, ORF7a and ORF7b showed conservation in terms of amino acid substitutions. Combined analysis with the frequently mutated residues identified 20 viral variants, among which 12 specific combinations comprised more than 97% of the isolates considered for the analysis. Some of the mutations across different proteins showed co-occurrences, suggesting their structural and/or functional interaction among different SARS-COV-2 proteins, and their involvement in adaptability and viral transmission. Analysis of protein structure stability of surface glycoprotein mutants indicated the viability of specific variants and are more prone to be temporally and spatially distributed across the globe. A similar empirical analysis of other proteins indicated the existence of important functional implications of several variants. Identification of frequently mutated variants among COVID-19 patients might be useful for better clinical management, contact tracing, and containment of the disease.

Title: Implications of SARS-CoV-2 mutations for genomic RNA structure and host microRNA targeting Content: The SARS-CoV-2 virus is a recently-emerged zoonotic pathogen already well adapted to transmission and replication in humans. Although the mutation rate is limited, recently introduced mutations in SARS-CoV-2 have the potential to alter viral fitness. In addition to amino acid changes, mutations could affect RNA secondary structure critical to viral life cycle, or interfere with sequences targeted by host miRNAs. We have analysed subsets of genomes from SARS-CoV-2 isolates from around the globe and show that several mutations introduce changes in Watson-Crick pairing, with resultant changes in predicted secondary structure. Filtering to targets matching miRNAs expressed in SARS-CoV-2 permissive host cells, we identified twelve separate target sequences in the SARS-CoV-2 genome; eight of these targets have been lost through conserved mutations. A genomic site targeted by the highly abundant miR-197-5p, overexpressed in patients with cardiovascular disease, is lost by a conserved mutation. Our results are compatible with a model that SARS-CoV-2 replication within the human host could be constrained by host miRNA defence. The impact of these and further mutations on secondary structures, miRNA targets or potential splice sites offers a new context in which to view future SARS-CoV-2 evolution, and a potential platform for engineered viral attenuation and antigen presentation.

Title: Implications of SARS-CoV-2 Mutations for Genomic RNA Structure and Host microRNA Targeting. Content: The SARS-CoV-2 virus is a recently-emerged zoonotic pathogen already well adapted to transmission and replication in humans. Although the mutation rate is limited, recently introduced mutations in SARS-CoV-2 have the potential to alter viral fitness. In addition to amino acid changes, mutations could affect RNA secondary structure critical to viral life cycle, or interfere with sequences targeted by host miRNAs. We have analysed subsets of genomes from SARS-CoV-2 isolates from around the globe and show that several mutations introduce changes in Watson-Crick pairing, with resultant changes in predicted secondary structure. Filtering to targets matching miRNAs expressed in SARS-CoV-2-permissive host cells, we identified ten separate target sequences in the SARS-CoV-2 genome; three of these targets have been lost through conserved mutations. A genomic site targeted by the highly abundant miR-197-5p, overexpressed in patients with cardiovascular disease, is lost by a conserved mutation. Our results are compatible with a model that SARS-CoV-2 replication within the human host is constrained by host miRNA defences. The impact of these and further mutations on secondary structures, miRNA targets or potential splice sites offers a new context in which to view future SARS-CoV-2 evolution, and a potential platform for engineering conditional attenuation to vaccine development, as well as providing a better understanding of viral tropism and pathogenesis.

Title: Implications of SARS-CoV-2 Mutations for Genomic RNA Structure and Host microRNA Targeting Content: The SARS-CoV-2 virus is a recently-emerged zoonotic pathogen already well adapted to transmission and replication in humans. Although the mutation rate is limited, recently introduced mutations in SARS-CoV-2 have the potential to alter viral fitness. In addition to amino acid changes, mutations could affect RNA secondary structure critical to viral life cycle, or interfere with sequences targeted by host miRNAs. We have analysed subsets of genomes from SARS-CoV-2 isolates from around the globe and show that several mutations introduce changes in Watson-Crick pairing, with resultant changes in predicted secondary structure. Filtering to targets matching miRNAs expressed in SARS-CoV-2-permissive host cells, we identified ten separate target sequences in the SARS-CoV-2 genome; three of these targets have been lost through conserved mutations. A genomic site targeted by the highly abundant miR-197-5p, overexpressed in patients with cardiovascular disease, is lost by a conserved mutation. Our results are compatible with a model that SARS-CoV-2 replication within the human host is constrained by host miRNA defences. The impact of these and further mutations on secondary structures, miRNA targets or potential splice sites offers a new context in which to view future SARS-CoV-2 evolution, and a potential platform for engineering conditional attenuation to vaccine development, as well as providing a better understanding of viral tropism and pathogenesis.

Title: Mutation Patterns of Human SARS-CoV-2 and Bat RaTG13 Coronavirus Genomes Are Strongly Biased Towards C>U Transitions, Indicating Rapid Evolution in Their Hosts Content: The pandemic caused by the spread of SARS-CoV-2 has led to considerable interest in its evolutionary origin and genome structure. Here, we analyzed mutation patterns in 34 human SARS-CoV-2 isolates and a closely related RaTG13 isolated from Rhinolophus affinis (a horseshoe bat). We also evaluated the CpG dinucleotide contents in SARS-CoV-2 and other human and animal coronavirus genomes. Out of 1136 single nucleotide variations (~4% divergence) between human SARS-CoV-2 and bat RaTG13, 682 (60%) can be attributed to C>U and U>C substitutions, far exceeding other types of substitutions. An accumulation of C>U mutations was also observed in SARS-CoV2 variants that arose within the human population. Globally, the C>U substitutions increased the frequency of codons for hydrophobic amino acids in SARS-CoV-2 peptides, while U>C substitutions decreased it. In contrast to most other coronaviruses, both SARS-CoV-2 and RaTG13 exhibited CpG depletion in their genomes. The data suggest that C-to-U conversion mediated by C deamination played a significant role in the evolution of the SARS-CoV-2 coronavirus. We hypothesize that the high frequency C>U transitions reflect virus adaptation processes in their hosts, and that SARS-CoV-2 could have been evolving for a relatively long period in humans following the transfer from animals before spreading worldwide.

Title: Mutation Patterns of Human SARS-CoV-2 and Bat RaTG13 Coronavirus Genomes Are Strongly Biased Towards C>U Transitions, Indicating Rapid Evolution in Their Hosts. Content: The pandemic caused by the spread of SARS-CoV-2 has led to considerable interest in its evolutionary origin and genome structure. Here, we analyzed mutation patterns in 34 human SARS-CoV-2 isolates and a closely related RaTG13 isolated from Rhinolophus affinis (a horseshoe bat). We also evaluated the CpG dinucleotide contents in SARS-CoV-2 and other human and animal coronavirus genomes. Out of 1136 single nucleotide variations (~4% divergence) between human SARS-CoV-2 and bat RaTG13, 682 (60%) can be attributed to C>U and U>C substitutions, far exceeding other types of substitutions. An accumulation of C>U mutations was also observed in SARS-CoV2 variants that arose within the human population. Globally, the C>U substitutions increased the frequency of codons for hydrophobic amino acids in SARS-CoV-2 peptides, while U>C substitutions decreased it. In contrast to most other coronaviruses, both SARS-CoV-2 and RaTG13 exhibited CpG depletion in their genomes. The data suggest that C-to-U conversion mediated by C deamination played a significant role in the evolution of the SARS-CoV-2 coronavirus. We hypothesize that the high frequency C>U transitions reflect virus adaptation processes in their hosts, and that SARS-CoV-2 could have been evolving for a relatively long period in humans following the transfer from animals before spreading worldwide.

Title: COVID-19 Variants Database: A repository for Human SARS-CoV-2 Polymorphism Data Content: COVID-19 is a newly communicable disease with a catastrophe outbreak that affects all over the world. We retrieved about 8,781 nucleotide fragments and complete genomes of SARS-CoV-2 reported from sixty-four countries. The CoV-2 reference genome was obtained from the National Genomics Data Center (NGDC), GISAID, and NCBI Genbank. All the sequences were aligned against reference genomes using Clustal Omega and variants were called using in-house built Python script. We intend to establish a user-friendly online resource to visualize the variants in the viral genome along with the Primer Infopedia. After analyzing and filtering the data globally, it was made available to the public. The detail of data available to the public includes mutations from 5688 SARS-CoV-2 sequences curated from 91 regions. This database incorporated 39920 mutations over 3990 unique positions. According to the translational impact, these mutations include 11829 synonymous mutations including 681 synonymous frameshifts and 21701 nonsynonymous mutations including 10 nonsynonymous frameshifts. Development of SARS-CoV-2 mutation genome browsers is a fundamental step obliging towards the virus surveillance, viral detection, and development of vaccine and therapeutic drugs. The SARS-COV-2 mutation browser is available at http://covid-19.dnageography.com.

Title: Molecular biological analysis of genotyping and phylogeny of severe acute respiratory syndrome associated coronavirus. Content: BACKGROUND SARS-CoV is the causative agent of severe acute respiratory syndrome (SARS) which has been associated with outbreaks of SARS in Guangdong, Hong Kong and Beijing of China, and other regions worldwide. SARS-CoV from human has shown some variations but its origin is still unknown. The genotyping and phylogeny of SARS-CoV were analyzed and reported in this paper. METHODS Full or partial genomes of 44 SARS-CoV strains were collected from GenBank. The genotype, single nucleotide polymorphism and phylogeny of these SARS-CoV strains were analyzed by molecular biological, bioinformatic and epidemiological methods. RESULTS There were 188 point mutations in the 33 virus full genomes with the counts of mutation mounting to 297. Further analysis was carried out among 36 of 188 loci with more than two times of mutation. All the 36 mutation loci occurred in coding sequences and 22 loci were non-synonymous. The gene mutation rates of replicase 1AB, S2 domain of spike glycoprotein and nucleocapsid protein were lower (0.079% - 0.103%). There were 4 mutation loci in S1 domain of spike glycoprotein. The gene mutation rate of ORF10 was the highest (3.333%) with 4 mutation loci in this small domain (120 bp) and 3 of 4 loci related to deletion mutation. By bioinformatics processing and analysis, the nucleotides at 7 loci of genome (T:T:A:G:T:C:T/C:G:G:A:C:T:C) can classify SARS-CoV into two types. Therefore a novel definition is put forward that according to these 7 loci of mutation, 40 strains of SARS-CoV in GenBank can be grouped into two genotypes, T:T:A:G:T:C:T and C:G:G:A:C:T:C, and named as SARS-CoV Yexin genotype and Xiaohong genotype. The two genotypes can be further divided into some sub-genotypes. These genotypes can also be approved by phylogenetic tree of three levels of 44 loci of mutation, spike glycoprotein gene and complete genome sequence. Compared to various strains among SARS-CoV Yexin genotype and Xiaohong genotype, GD01 strain of Yexin genotype is more closely related to SARS-CoV like-virus from animals. CONCLUSION The results mentioned above suggest that SARS-CoV is responding to host immunological pressures and experiencing variation which provide clues, information and evidence of molecular biology for the clinical pathology, vaccine developing and epidemic investigation.

Title: Structural and Functional Implications of Spike Protein Mutational Landscape in SARS-CoV-2 Content: SARS-CoV-2, the causative agent of COVID-19 pandemic, is an RNA virus prone to mutations. Interaction of SARS-CoV-2 Spike (S) protein with the host cell receptor, Angiotensin-I Converting Enzyme 2 (ACE2) is pivotal for attachment and entry of the virus. Yet, natural mutations acquired on S protein during the pandemic and their impact on viral infectivity, transmission dynamics and disease pathogenesis remains poorly understood. Here, we analysed 2952 SARS-CoV-2 genomes across the globe, and identified a total of 1815 non-synonymous mutations in the S-protein that fall into 54 different types. We observed that six of these distinct mutations were located in the Receptor Binding Domain (RBD) region that directly engages host ACE2. Molecular phylogenetic analysis revealed that these RBD mutations cluster into distinct phyletic clades among global subtypes of SARS-CoV-2 implying possible emergence of novel sublineages of the strain. Structure-guided homology modelling and docking analysis predicted key molecular rearrangements in the ACE2 binding interface of RBD mutants that could result in altered virus-host interactions. We propose that our findings could be significant in understanding disease dynamics and in developing vaccines, antibodies and therapeutics for COVID-19. Importance COVID-19 pandemic shows considerable variations in disease transmission and pathogenesis globally, yet reasons remain unknown. Our study identifies key S-protein mutations prevailing in SARS-CoV-2 strain that could alter viral attachment and infectivity. We propose that the interplay of these mutations could be one of the factors driving global variations in COVID-19 spread. In addition, the mutations identified in this study could be an important indicator in predicting efficacies of vaccines, antibodies and therapeutics that target SARS-CoV-2 RBD-ACE2 interface.

Title: High Throughput Designing and Mutational Mapping of RBD-ACE2 Interface Guide Non-Conventional Therapeutic Strategies for COVID-19 Content: Considering the current status of the SARS-CoV-2 pandemic, sequence variations and possibly structural changes in the rapidly evolving SARS-CoV-2 is highly expected in the coming months. The SARS-CoV-2 spike (S) protein is responsible for mediating viral attachment and fusion with cell membranes. Mutations in the receptor-binding domain (RBD) of the S-protein occur at the most variable part of the SARS-CoV-2 genome, and specific sites of S-protein have undergone positive selection impacting the viral pathogenicity. In the present work, we used high-throughput computation to design 100,000 mutants in RBD interfacial residues and identify novel affinity-enhancing and affinity-weakening mutations. Our data suggest that SARS-CoV-2 can establish a higher rate of infectivity and pathogenesis when it acquires combinatorial mutations at the interfacial residues in RBD. Mapping of the mutational landscape of the interaction site suggests that a few of these residues are the hot-spot residues with a very high tendency to undergo positive selection. Knowledge of the affinity-enhancing mutations may guide the identification of potential cold-spots for this mutation as targets for developing a possible therapeutic strategy instead of hot-spots, and vice versa. Understanding of the molecular interactions between the virus and host protein presents a detailed systems view of viral infection mechanisms. The applications of the present research can be explored in multiple antiviral strategies, including monoclonal antibody therapy, vaccine design, and importantly in understanding the clinical pathogenesis of the virus itself. Our work presents research directions for the exploitation of non-conventional solutions for COVID-19.

Title: The novel coronavirus SARS-CoV-2: From a zoonotic infection to coronavirus disease 2019 Content: The novel coronavirus (CoV), severe acute respiratory syndrome (SARS)-CoV-2 is an international public health emergency. Until now, the intermediate host and mechanisms of the interspecies jump of this virus are unknown. Phylogenetic analysis of all available bat CoV complete genomes was performed to analyze the relationships between bat CoV and SARS-CoV-2. To suggest a possible intermediate host, another phylogenetic reconstruction of CoV genomes obtained from animals that were hypothetically commercialized in the Chinese markets was also carried out. Moreover, mutation analysis was executed to suggest genomic regions that may have permitted the adaptation of SARS-CoV-2 to the human host. The phylogenetic analysis demonstrated that SARS-CoV-2 formed a cluster with the bat CoV isolate RaTG13. Possible CoV interspecies jumps among bat isolates were also observed. The phylogenetic tree reconstructed from CoV strains belonging to different animals demonstrated that SARS-CoV-2, bat RaTG13, and pangolin CoV genomes formed a monophyletic cluster, demonstrating that pangolins may be suggested as SARS-CoV-2 intermediate hosts. Three AA substitutions localized in the S1 portion of the S gene were observed, some of which have been correlated to structural modifications of the S protein which may facilitate SARS-CoV-2 tropism to human cells. Our analysis shows the tight relationship between SARS-CoV-2 and bat SARS-like strains. It also hypothesizes that pangolins might have been possible intermediate hosts of the infection. Some of the observed AA substitutions in the S-binding protein may serve as possible adaptation mutations in humans but more studies are needed to elucidate their function.

Title: Patient-derived mutations impact pathogenicity of SARS-CoV-2 Content: The sudden outbreak of the severe acute respiratory syndrome-coronavirus (SARS-CoV-2) has spread globally with more than 1,300,000 patients diagnosed and a death toll of 70,000. Current genomic survey data suggest that single nucleotide variants (SNVs) are abundant. However, no mutation has been directly linked with functional changes in viral pathogenicity. Here we report functional characterizations of 11 patient-derived viral isolates, all of which have at least one mutation. Importantly, these viral isolates show significant variation in cytopathic effects and viral load, up to 270-fold differences, when infecting Vero-E6 cells. We observed intrapersonal variation and 6 different mutations in the spike glycoprotein (S protein), including 2 different SNVs that led to the same missense mutation. Therefore, we provide direct evidence that the SARS-CoV-2 has acquired mutations capable of substantially changing its pathogenicity.

Title: Mutational dynamics of the SARS coronavirus in cell culture and human populations isolated in 2003 Content: BACKGROUND: The SARS coronavirus is the etiologic agent for the epidemic of the Severe Acute Respiratory Syndrome. The recent emergence of this new pathogen, the careful tracing of its transmission patterns, and the ability to propagate in culture allows the exploration of the mutational dynamics of the SARS-CoV in human populations. METHODS: We sequenced complete SARS-CoV genomes taken from primary human tissues (SIN3408, SIN3725V, SIN3765V), cultured isolates (SIN848, SIN846, SIN842, SIN845, SIN847, SIN849, SIN850, SIN852, SIN3408L), and five consecutive Vero cell passages (SIN2774_P1, SIN2774_P2, SIN2774_P3, SIN2774_P4, SIN2774_P5) arising from SIN2774 isolate. These represented individual patient samples, serial in vitro passages in cell culture, and paired human and cell culture isolates. Employing a refined mutation filtering scheme and constant mutation rate model, the mutation rates were estimated and the possible date of emergence was calculated. Phylogenetic analysis was used to uncover molecular relationships between the isolates. RESULTS: Close examination of whole genome sequence of 54 SARS-CoV isolates identified before 14(th )October 2003, including 22 from patients in Singapore, revealed the mutations engendered during human-to-Vero and Vero-to-human transmission as well as in multiple Vero cell passages in order to refine our analysis of human-to-human transmission. Though co-infection by different quasipecies in individual tissue samples is observed, the in vitro mutation rate of the SARS-CoV in Vero cell passage is negligible. The in vivo mutation rate, however, is consistent with estimates of other RNA viruses at approximately 5.7 × 10(-6 )nucleotide substitutions per site per day (0.17 mutations per genome per day), or two mutations per human passage (adjusted R-square = 0.4014). Using the immediate Hotel M contact isolates as roots, we observed that the SARS epidemic has generated four major genetic groups that are geographically associated: two Singapore isolates, one Taiwan isolate, and one North China isolate which appears most closely related to the putative SARS-CoV isolated from a palm civet. Non-synonymous mutations are centered in non-essential ORFs especially in structural and antigenic genes such as the S and M proteins, but these mutations did not distinguish the geographical groupings. However, no non-synonymous mutations were found in the 3CLpro and the polymerase genes. CONCLUSIONS: Our results show that the SARS-CoV is well adapted to growth in culture and did not appear to undergo specific selection in human populations. We further assessed that the putative origin of the SARS epidemic was in late October 2002 which is consistent with a recent estimate using cases from China. The greater sequence divergence in the structural and antigenic proteins and consistent deletions in the 3' – most portion of the viral genome suggest that certain selection pressures are interacting with the functional nature of these validated and putative ORFs.

Title: Evidence of the Recombinant Origin and Ongoing Mutations in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Content: The recent global outbreak of viral pneumonia designated as Coronavirus Disease 2019 (COVID-19) by coronavirus (SARS-CoV-2) has threatened global public health and urged to investigate its source. Whole genome analysis of SARS-CoV-2 revealed ~96% genomic similarity with bat CoV (RaTG13) and clustered together in phylogenetic tree. Furthermore, RaTGl3 also showed 97.43% spike protein similarity with SARS-CoV-2 suggesting that RaTGl3 is the closest strain. However, RBD and key amino acid residues supposed to be crucial for human-to-human and cross-species transmission are homologues between SARS-CoV-2 and pangolin CoVs. These results from our analysis suggest that SARS-CoV-2 is a recombinant virus of bat and pangolin CoVs. Moreover, this study also reports mutations in coding regions of 125 SARS-CoV-2 genomes signifying its aptitude for evolution. In short, our findings propose that homologous recombination has been occurred between bat and pangolin CoVs that triggered cross-species transmission and emergence of SARS-CoV-2, and, during the ongoing outbreak, SARS-CoV-2 is still evolving for its adaptability.

Title: The novel Coronavirus enigma: Phylogeny and mutation analyses of SARS-CoV-2 viruses circulating in India during early 2020 Content: Background This is a comprehensive analysis of 46 Indian SARS-CoV-2 genome sequences available from the NCBI and GISAID repository during early 2020. Evolutionary dynamics, gene-specific phylogeny and emergence of the novel co-evolving mutations in nine structural and non-structural genes among circulating SARS-CoV-2 strains in ten states of India have been assessed. Materials and methods 46 SARS-CoV-2 nucleotide sequences submitted from India were downloaded from the GISAID (39/46) or from NCBI (7/46) database. Phylogenetic study and analyses of mutation were based on the nine structural and non-structural genes of SARS-CoV-2 strains. Secondary structure of RdRP/NSP12 protein was predicted with respect to the novel A97V mutation. Results Phylogenetic analyses revealed the evolution of “genome-type clusters” and adaptive selection of “L” type SARS-CoV-2 strains with genetic closeness to the bat SARS-like coronaviruses than pangolin or MERS-CoVs. With regards to the novel co-evolving mutations, 2 groups are seen to circulate in India at present: the “major group” (52.2%) and the “minor group” (30.4%), harboring four and five co-existing mutations, respectively. The “major group” mutations fall in the A2a clade. All the minor group mutations, except 11083G>T (L37F, NSP6) were unique to the Indian isolates. Conclusion The study highlights rapidly evolving SARS-CoV-2 virus and co-circulation of multiple clades and sub-clades, driving this pandemic worldwide. This comprehensive study is a potential resource for monitoring the novel mutations in the viral genome, changes in viral pathogenesis, for designing vaccines and other therapeutics.

Title: Epidemiological and Genomic Analysis of SARS-CoV-2 in Ten Patients from a Mid-sized City outside of Hubei, China Content: A novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the ongoing COVID-19 pandemic. In this study, we performed a comprehensive epidemiological and genomic analysis of SARS-CoV-2 genomes from ten patients in Shaoxing, a mid-sized city outside of the epicenter Hubei province, China, during the early stage of the outbreak (late January to early February, 2020). We obtained viral genomes with > 99% coverage and a mean depth of 296X demonstrating that viral genomic analysis is feasible via metagenomics sequencing directly on nasopharyngeal samples with SARS-CoV-2 Real-time PCR Ct values less than 28. We found that a cluster of 4 patients with travel history to Hubei shared the exact same virus with patients from Wuhan, Taiwan, Belgium and Australia, highlighting how quickly this virus spread to the globe. The virus from another cluster of husband and wife without travel history but with a sick contact of a confirmed case from another city outside of Hubei accumulated significantly more mutations (9 SNPs vs average 4 SNPs), suggesting a complex and dynamic nature of this outbreak. We also found 70% patients in this study had the S genotype, consistent with an early study showing a higher prevalence of S genotype out of Hubei than that inside Hubei. We calculated an average mutation rate of 1.37x10-3 nucleotide substitution per site per year, which is similar to that of other coronaviruses. Our findings add to the growing knowledge of the epidemiological and genomic characteristics of SARS-CoV-2 that are important for guiding outbreak containment and vaccine development. The moderate mutation rate of this virus also lends hope that development of an effective, long-lasting vaccine may be possible.

Title: Evolving geographic diversity in SARS-CoV2 and in silico analysis of replicating enzyme 3CL(pro) targeting repurposed drug candidates Content: BACKGROUND: Severe acute respiratory syndrome (SARS) has been initiating pandemics since the beginning of the century. In December 2019, the world was hit again by a devastating SARS episode that has so far infected almost four million individuals worldwide, with over 200,000 fatalities having already occurred by mid-April 2020, and the infection rate continues to grow exponentially. SARS coronavirus 2 (SARS-CoV-2) is a single stranded RNA pathogen which is characterised by a high mutation rate. It is vital to explore the mutagenic capability of the viral genome that enables SARS-CoV-2 to rapidly jump from one host immunity to another and adapt to the genetic pool of local populations. METHODS: For this study, we analysed 2301 complete viral sequences reported from SARS-CoV-2 infected patients. SARS-CoV-2 host genomes were collected from The Global Initiative on Sharing All Influenza Data (GISAID) database containing 9 genomes from pangolin-CoV origin and 3 genomes from bat-CoV origin, Wuhan SARS-CoV2 reference genome was collected from GeneBank database. The Multiple sequence alignment tool, Clustal Omega was used for genomic sequence alignment. The viral replicating enzyme, 3-chymotrypsin-like cysteine protease (3CL(pro)) that plays a key role in its pathogenicity was used to assess its affinity with pharmacological inhibitors and repurposed drugs such as anti-viral flavones, biflavanoids, anti-malarial drugs and vitamin supplements. RESULTS: Our results demonstrate that bat-CoV shares > 96% similar identity, while pangolin-CoV shares 85.98% identity with Wuhan SARS-CoV-2 genome. This in-depth analysis has identified 12 novel recurrent mutations in South American and African viral genomes out of which 3 were unique in South America, 4 unique in Africa and 5 were present in-patient isolates from both populations. Using state of the art in silico approaches, this study further investigates the interaction of repurposed drugs with the SARS-CoV-2 3CL(pro) enzyme, which regulates viral replication machinery. CONCLUSIONS: Overall, this study provides insights into the evolving mutations, with implications to understand viral pathogenicity and possible new strategies for repurposing compounds to combat the nCovid-19 pandemic.

Title: Evolving geographic diversity in SARS-CoV2 and in silico analysis of replicating enzyme 3CLpro targeting repurposed drug candidates Content: BACKGROUND: Severe acute respiratory syndrome (SARS) has been initiating pandemics since the beginning of the century. In December 2019, the world was hit again by a devastating SARS episode that has so far infected almost four million individuals worldwide, with over 200,000 fatalities having already occurred by mid-April 2020, and the infection rate continues to grow exponentially. SARS coronavirus 2 (SARS-CoV-2) is a single stranded RNA pathogen which is characterised by a high mutation rate. It is vital to explore the mutagenic capability of the viral genome that enables SARS-CoV-2 to rapidly jump from one host immunity to another and adapt to the genetic pool of local populations. METHODS: For this study, we analysed 2301 complete viral sequences reported from SARS-CoV-2 infected patients. SARS-CoV-2 host genomes were collected from The Global Initiative on Sharing All Influenza Data (GISAID) database containing 9 genomes from pangolin-CoV origin and 3 genomes from bat-CoV origin, Wuhan SARS-CoV2 reference genome was collected from GeneBank database. The Multiple sequence alignment tool, Clustal Omega was used for genomic sequence alignment. The viral replicating enzyme, 3-chymotrypsin-like cysteine protease (3CLpro) that plays a key role in its pathogenicity was used to assess its affinity with pharmacological inhibitors and repurposed drugs such as anti-viral flavones, biflavanoids, anti-malarial drugs and vitamin supplements. RESULTS: Our results demonstrate that bat-CoV shares > 96% similar identity, while pangolin-CoV shares 85.98% identity with Wuhan SARS-CoV-2 genome. This in-depth analysis has identified 12 novel recurrent mutations in South American and African viral genomes out of which 3 were unique in South America, 4 unique in Africa and 5 were present in-patient isolates from both populations. Using state of the art in silico approaches, this study further investigates the interaction of repurposed drugs with the SARS-CoV-2 3CLpro enzyme, which regulates viral replication machinery. CONCLUSIONS: Overall, this study provides insights into the evolving mutations, with implications to understand viral pathogenicity and possible new strategies for repurposing compounds to combat the nCovid-19 pandemic.

Title: The Novel Coronavirus SARS‐CoV‐2: From a Zoonotic Infection to Coronavirus Disease‐19 (COVID19) Content: OBJECTIVE: The novel coronavirus, SARS‐CoV‐2 is an international public health emergency. Until now, the intermediate host and mechanisms of interspecies jump of this virus are unknown. METHODS: Phylogenetic analysis of all available bat coronavirus (CoV) complete genomes was performed in order to analyze the relationships between bat CoV and SARS‐CoV‐2. In order to suggest a possible intermediate host, another phylogenetic reconstruction of CoV genomes obtained from animals which were hypothetically commercialized in the Chinese markets was also carried out. Moreover, mutation analysis was executed to suggest genomic regions which may have permitted the adaptation of SARS‐CoV‐2 to the human host. RESULTS: The phylogenetic analysis demonstrated that SARS‐CoV‐2 formed a cluster with the bat CoV isolate RaTG13. Possible CoV interspecies jumps among bat isolates were also observed. The phylogenetic tree reconstructed from CoV strains belonging to different animals demonstrated that SARS‐CoV‐2, bat RaTG13 and pangolin CoV genomes formed a monophyletic cluster, demonstrating that pangolins may be suggested as SARS‐CoV‐2 intermediate hosts. Three AA substitutions localized in the S1 portion of the S gene were observed, some of which have been correlated to structural modifications of the S protein which may facilitate SARS‐CoV‐2 tropism to human cells. CONCLUSIONS: Our analysis shows the tight relationship between SARS‐CoV‐2 and bat SARS‐like strains. It also hypothesizes that pangolins might have been possible intermediate hosts of the infection. Some of the observed AA substitutions in the S binding protein may serve as possible adaptation mutations in humans but more studies are needed to elucidate their function. This article is protected by copyright. All rights reserved.

Title: Anti-frameshifting ligand active against SARS coronavirus-2 is resistant to natural mutations of the frameshift-stimulatory pseudoknot Content: The coronavirus SARS-CoV-2 causing the COVID-19 pandemic uses −1 programmed ribosomal frameshifting (−1 PRF) to control the expression levels of key viral proteins. Because modulating −1 PRF can attenuate viral propagation, ligands binding to the viral RNA pseudoknot that stimulates −1 PRF may prove useful as therapeutics. Mutations in the pseudoknot have been observed over the course of the pandemic, but how they affect −1 PRF and the activity of inhibitors is unknown. Cataloguing natural mutations in all parts of the SARS-CoV-2 pseudoknot, we studied a panel of 6 mutations in key structural regions. Most mutations left the −1 PRF efficiency unchanged, even when base-pairing was disrupted, but one led to a remarkable three-fold decrease, suggesting that SARS-CoV-2 propagation may be less sensitive to modulation of −1 PRF efficiency than some other viruses. Examining the effects of one of the few small-molecule ligands known to suppress −1 PRF significantly in SARS-CoV, we found that it did so by similar amounts in all SARS-CoV-2 mutants tested, regardless of the basal −1 PRF efficiency, indicating that the activity of anti-frameshifting ligands can be resistant to natural pseudoknot mutations. These results have important implications for therapeutic strategies targeting SARS-CoV-2 through modulation of −1 PRF.

Title: Comparative genomic analysis revealed specific mutation pattern between human coronavirus SARS-CoV-2 and Bat-SARSr-CoV RaTG13 Content: The novel coronavirus SARS-CoV-2 (2019-nCoV) is a member of the family coronaviridae and contains a single-stranded RNA genome with positive-polarity. To reveal the evolution mechanism of SARS-CoV-2 genome, we performed comprehensive genomic analysis with newly sequenced SARS-CoV-2 strains and 20 closely related coronavirus strains. Among 98 nucleotide mutations at 93 sites of the genome among different SARS-CoV-2 strains, 58 of them caused amino acid change, indicating a result of neutral evolution. However, the ratio of nucleotide substitutions to amino acid substitutions of spike gene (9.07) between SARS-CoV-2 WIV04 and Bat-SARSr-CoV RaTG13 was extensively higher than those from comparisons between other coronaviruses (range 1.29 - 4.81). The elevated synonymous mutations between SARS-CoV-2 and RaTG13, suggesting they underwent stronger purifying selection. Moreover, their nucleotide substitutions are enriched with T:C transition, which is consistent with the mutation signature caused by deactivity of RNA 3’-to-5’ exoribonuclease (ExoN). The codon usage was similar between SARS-CoV-2 and other strains in beta-coronavirus lineage B, suggesting it had small impact on the mutation pattern. In comparison of SARS-CoV-2 WIV04 with Bat-SARSr-CoV RaTG13, the ratios of non-synonymous to synonymous substitution rates (dN/dS) was the lowest among all performed comparisons, reconfirming the evolution of SARS-CoV-2 under stringent selective pressure. Moreover, some sites of spike protein might be subjected to positive selection. Therefore, our results will help understanding the evolutionary mechanisms contribute to viral pathogenicity and its adaptation with hosts.

Title: Identification of unique mutations in SARS-CoV-2 strains isolated from India suggests its attenuated pathotype Content: Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which was first reported in Wuhan, China in November 2019 has developed into a pandemic since March 2020, causing substantial human casualties and economic losses. Studies on SARS-CoV-2 are being carried out at an unprecedented rate to tackle this threat. Genomics studies, in particular, are indispensable to elucidate the dynamic nature of the RNA genome of SARS-CoV-2. RNA viruses are marked by their unique ability to undergo high rates of mutation in their genome, much more frequently than their hosts, which diversifies their strengths qualifying them to elude host immune response and amplify drug resistance. In this study, we sequenced and analyzed the genomic information of the SARS-CoV-2 isolates from two infected Indian patients and explored the possible implications of point mutations in its biology. In addition to multiple point mutations, we found a remarkable similarity between relatively common mutations of 36-nucleotide deletion in ORF8 of SARS-CoV-2. Our results corroborate with the earlier reported 29-nucleotide deletion in SARS, which was frequent during the early stage of human-to-human transmission. The results will be useful to understand the biology of SARS-CoV-2 and itsattenuation for vaccine development.

Title: SARS-CoV-2 spread across the Colombian-Venezuelan border Content: Venezuela and Colombia both adopted measures of containment early in response to the COVID-19 pandemic. However, Venezuelan ongoing humanitarian crisis has decimated its health care system, and forced millions of Venezuelans to flee through its porous border with Colombia. The extensive shared border, and illegal cross-border transit through improvised trails between the two countries are major challenges for public health authorities. We report the first SARS-CoV-2 genomes from Venezuela, and present a snapshot of the SARS-CoV-2 epidemiologic landscape in the Colombian-Venezuelan border region. We sequenced and assembled viral genomes from total RNA extracted from nasopharyngeal (NP) clinical specimens using a custom reference-based analysis pipeline. Three assemblies obtained were subjected to typing using the Phylogenetic Assignment of Named Global Outbreak LINeages Pangolin tool. A total of 376 publicly available SARS-CoV-2 genomes from South America were obtained from the GISAID database to perform comparative genomic analyses. Additionally, the Wuhan-1 strain was used as reference. We found that two of the SARS-CoV-2 genomes from Venezuela belonged to the B1 lineage, and the third to the B.1.13 lineage. We observed a point mutation in the Spike protein gene (D614G substitution), previously reported to be associated with increased infectivity, in all three Venezuelan genomes. An additional three mutations (R203K/G204R substitution) were present in the nucleocapsid (N) gene of one Venezuelan genome. Conclusions: Genomic sequencing demonstrates similarity between SARS-CoV-2 lineages from Venezuela and viruses collected from patients in bordering areas in Colombia and from Brazil, consistent with cross-border transit despite administrative measures including lockdowns. The presence of mutations associated with increased infectivity in the 3 Venezuelan genomes we report and Colombian SARS-CoV-2 genomes from neighboring borders areas may pose additional challenges for control of SARS-CoV-2 spread in the complex epidemiological landscape in Latin American countries. Public health authorities should carefully follow the progress of the pandemic and its impact on displaced populations within the region.

Title: [Follow up study on viruses associated with SARS among the SARS patients]. Content: BACKGROUND To study the existence status of the SARS-CoV, retrovirus, and the poliovirus in the bodies of the patients with SARS and the possible relationship between the three viruses and SARS. METHODS The clinical specimens of the nasopharyngeal swabs, sputum (or saliva), urine, fecal specimens were collected on three consecutive days from 8 patients with SARS 2 years after the recovery from SARS. SARS-CoV, reovirus and poliovirus RNA was detected by using reverse transcription (RT)-PCR; IgG antibody to the poliovirus type 1 and 3 and the antibody to SARS-CoV were determined using enzyme linked immunosorbent assay (ELISA). RESULTS All the specimens were negative for SARS-CoV and reovirus by RT-PCR, but the fecal specimens from 4 persons were positive for poliovirus. The sequences of these poliovirus were highly homologous to that of human poliovirus type 1 strain sabin 1 genome at nucleotide level, but back mutations have occurred in the primary attenuating mutation sites at nucleotide position 480 (G --> A) in the 5' UTR and the nucleotide position 2795 (A --> G). No SARS-CoV, reovirus, and poliovirus were found in the normal controls. Three serum specimens were positive for the antibody to SARS-CoV. The IgG antibody to poliovirus were detected in 4 SARS patients and 23 healthy persons. No positive results for antibody to SARS-CoV were detected in the 25 healthy persons. CONCLUSION The positive rate of the poliovirus antibody in the serum of SARS patients 2 years after recovery was significantly different from that of the normal controls, and the positive rate of poliovirus in the fecal specimens was still very high, and more importantly back mutations have occurred in the attenuating mutation sites at nucleotide position which plays an important role in the poliomyelitis.

Title: Molecular Evolution of SARS-CoV-2 Structural Genes: Evidence of Positive Selection in Spike Glycoprotein Content: SARS-CoV-2 caused a global pandemic in early 2020 and has resulted in more than 8,000,000 infections as well as 430,000 deaths in the world so far. Four structural proteins, envelope (E), membrane (M), nucleocapsid (N) and spike (S) glycoprotein, play a key role in controlling the entry into human cells and virion assembly of SARS-CoV-2. However, how these genes evolve during its human to human transmission is largely unknown. In this study, we screened and analyzed roughly 3090 SARS-CoV-2 isolates from GenBank database. The distribution of the four gene alleles is determined:16 for E, 40 for M, 131 for N and 173 for S genes. Phylogenetic analysis shows that global SARS-CoV-2 isolates can be clustered into three to four major clades based on the protein sequences of these genes. Intragenic recombination event isn’t detected among different alleles. However, purifying selection has conducted on the evolution of these genes. By analyzing full genomic sequences of these alleles using codon-substitution models (M8, M3 and M2a) and likelihood ratio tests (LRTs) of codeML package, it reveals that codon 614 of S glycoprotein has subjected to strong positive selection pressure and a persistent D614G mutation is identified. The definitive positive selection of D614G mutation is further confirmed by internal fixed effects likelihood (IFEL) and Evolutionary Fingerprinting methods implemented in Hyphy package. In addition, another potential positive selection site at codon 5 in the signal sequence of the S protein is also identified. The allele containing D614G mutation has undergone significant expansion during SARS-CoV-2 global pandemic, implying a better adaptability of isolates with the mutation. However, L5F allele expansion is relatively restricted. The D614G mutation is located at the subdomain 2 (SD2) of C-terminal portion (CTP) of the S1 subunit. Protein structural modeling shows that the D614G mutation may cause the disruption of salt bridge among S protein monomers increase their flexibility, and in turn promote receptor binding domain (RBD) opening, virus attachment and entry into host cells. Located at the signal sequence of S protein as it is, L5F mutation may facilitate the protein folding, assembly, and secretion of the virus. This is the first evidence of positive Darwinian selection in the spike gene of SARS-CoV-2, which contributes to a better understanding of the adaptive mechanism of this virus and help to provide insights for developing novel therapeutic approaches as well as effective vaccines by targeting on mutation sites.

Title: Genomic characterization of a novel SARS-CoV-2 Content: A new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated with human to human transmission and extreme human sickness has been as of late announced from the city of Wuhan in China. Our objectives were to mutation analysis between recently reported genomes at various times and locations and to characterize the genomic structure of SARS-CoV-2 using bioinformatics programs. Information on the variation of viruses is of considerable medical and biological impacts on the prevention, diagnosis, and therapy of infectious diseases. To understand the genomic structure and variations of the SARS-CoV-2. The study analyzed 95 SARS-CoV-2 complete genome sequences available in GenBank, National MicrobiologyData Center (NMDC) and NGDC Genome Warehouse from December-2019 until 05 of April-2020. The genomic signature analysis demonstrates that a strong association between the time of sample collection, location of sample and accumulation of genetic diversity. We found 116 mutations, the three most common mutations were 8782C>T in ORF1ab gene, 28144T>C in ORF8 gene and 29095C>T in the N gene. The mutations might affect the severity and spread of the SARS-CoV-2. The finding heavily supports an intense requirement for additional prompt, inclusive investigations that combine genomic detail, epidemiological information and graph records of the clinical features of patients with COVID-19.

Title: Genomic characterization of a novel SARS-CoV-2 Content: Abstract A new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated with human to human transmission and extreme human sickness has been as of late announced from the city of Wuhan in China. Our objectives were to mutation analysis between recently reported genomes at various times and locations and to characterize the genomic structure of SARS-CoV-2 using bioinformatics programs. Information on the variation of viruses is of considerable medical and biological impacts on the prevention, diagnosis, and therapy of infectious diseases. To understand the genomic structure and variations of the SARS-CoV-2. The study analyzed 95 SARS-CoV-2 complete genome sequences available in GenBank, National MicrobiologyData Center (NMDC) and NGDC Genome Warehouse from December-2019 until 05 of April-2020. The genomic signature analysis demonstrates that a strong association between the time of sample collection, location of sample and accumulation of genetic diversity. We found 116 mutations, the three most common mutations were 8782C>T in ORF1ab gene, 28144T>C in ORF8 gene and 29095C>T in the N gene. The mutations might affect the severity and spread of the SARS-CoV-2. The finding heavily supports an intense requirement for additional prompt, inclusive investigations that combine genomic detail, epidemiological information and graph records of the clinical features of patients with COVID-19.

Title: Deep mutational scanning of SARS-CoV-2 receptor binding domain reveals constraints on folding and ACE2 binding Content: The receptor binding domain (RBD) of the SARS-CoV-2 spike glycoprotein mediates viral attachment to ACE2 receptor, and is a major determinant of host range and a dominant target of neutralizing antibodies. Here we experimentally measure how all amino-acid mutations to the RBD affect expression of folded protein and its affinity for ACE2. Most mutations are deleterious for RBD expression and ACE2 binding, and we identify constrained regions on the RBD’s surface that may be desirable targets for vaccines and antibody-based therapeutics. But a substantial number of mutations are well tolerated or even enhance ACE2 binding, including at ACE2 interface residues that vary across SARS-related coronaviruses. However, we find no evidence that these ACE2-affinity enhancing mutations have been selected in current SARS-CoV-2 pandemic isolates. We present an interactive visualization and open analysis pipeline to facilitate use of our dataset for vaccine design and functional annotation of mutations observed during viral surveillance.

Title: D936Y and Other Mutations in the Fusion Core of the SARS-Cov-2 Spike Protein Heptad Repeat 1 Undermine the Post-Fusion Assembly Content: The iconic “red crown” of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is made of its spike (S) glycoprotein. The S protein is the Trojan horse of coronaviruses, mediating their entry into the host cells. While SARS-CoV-2 was becoming a global threat, scientists have been accumulating data on the virus at an impressive pace, both in terms of genomic sequences and of three-dimensional structures. On April 21st, the GISAID resource had collected 10,823 SARS-CoV-2 genomic sequences. We extracted from them all the complete S protein sequences and identified point mutations thereof. Six mutations were located on a 14-residue segment (929-943) in the “fusion core” of the heptad repeat 1 (HR1). Our modeling in the pre- and post-fusion S protein conformations revealed, for three of them, the loss of interactions stabilizing the post-fusion assembly. On May 29th, the SARS-CoV-2 genomic sequences in GISAID were 34,805. An analysis of the occurrences of the HR1 mutations in this updated dataset revealed a significant increase for the S929I and S939F mutations and a dramatic increase for the D936Y mutation, which was particularly widespread in Sweden and Wales/England. We notice that this is also the mutation causing the loss of a strong inter-monomer interaction, the D936-R1185 salt bridge, thus clearly weakening the post-fusion assembly.

Title: Molecular determinants of severe acute respiratory syndrome coronavirus pathogenesis and virulence in young and aged mouse models of human disease. Content: SARS coronavirus (SARS-CoV) causes severe acute respiratory tract disease characterized by diffuse alveolar damage and hyaline membrane formation. This pathology often progresses to acute respiratory distress (such as acute respiratory distress syndrome [ARDS]) and atypical pneumonia in humans, with characteristic age-related mortality rates approaching 50% or more in immunosenescent populations. The molecular basis for the extreme virulence of SARS-CoV remains elusive. Since young and aged (1-year-old) mice do not develop severe clinical disease following infection with wild-type SARS-CoV, a mouse-adapted strain of SARS-CoV (called MA15) was developed and was shown to cause lethal infection in these animals. To understand the genetic contributions to the increased pathogenesis of MA15 in rodents, we used reverse genetics and evaluated the virulence of panels of derivative viruses encoding various combinations of mouse-adapted mutations. We found that mutations in the viral spike (S) glycoprotein and, to a much less rigorous extent, in the nsp9 nonstructural protein, were primarily associated with the acquisition of virulence in young animals. The mutations in S likely increase recognition of the mouse angiotensin-converting enzyme 2 (ACE2) receptor not only in MA15 but also in two additional, independently isolated mouse-adapted SARS-CoVs. In contrast to the findings for young animals, mutations to revert to the wild-type sequence in nsp9 and the S glycoprotein were not sufficient to significantly attenuate the virus compared to other combinations of mouse-adapted mutations in 12-month-old mice. This panel of SARS-CoVs provides novel reagents that we have used to further our understanding of differential, age-related pathogenic mechanisms in mouse models of human disease.

Title: Rampant C->U hypermutation in the genomes of SARS-CoV-2 and other coronaviruses – causes and consequences for their short and long evolutionary trajectories Content: The pandemic of SARS coronavirus 2 (SARS-CoV-2) has motivated an intensive analysis of its molecular epidemiology following its worldwide spread. To understand the early evolutionary events following its emergence, a dataset of 985 complete SARS-CoV-2 sequences was assembled. Variants showed a mean 5.5-9.5 nucleotide differences from each other, commensurate with a mid-range coronavirus substitution rate of 3×10−4 substitutions/site/year. Almost half of sequence changes were C->U transitions with an 8-fold base frequency normalised directional asymmetry between C->U and U->C substitutions. Elevated ratios were observed in other recently emerged coronaviruses (SARS-CoV and MERS-CoV) and to a decreasing degree in other human coronaviruses (HCoV-NL63, -OC43, -229E and -HKU1) proportionate to their increasing divergence. C->U transitions underpinned almost half of the amino acid differences between SARS-CoV-2 variants, and occurred preferentially in both 5’U/A and 3’U/A flanking sequence contexts comparable to favoured motifs of human APOBEC3 proteins. Marked base asymmetries observed in non-pandemic human coronaviruses (U>>A>G>>C) and low G+C contents may represent long term effects of prolonged C->U hypermutation in their hosts. Importance The evidence that much of sequence change in SARS-CoV-2 and other coronaviruses may be driven by a host APOBEC-like editing process has profound implications for understanding their short and long term evolution. Repeated cycles of mutation and reversion in favoured mutational hotspots and the widespread occurrence of amino acid changes with no adaptive value for the virus represents a quite different paradigm of virus sequence change from neutral and Darwinian evolutionary frameworks that are typically used in molecular epidemiology investigations.

Title: Tracing two causative SNPs reveals SARS-CoV-2 transmission in North America population Content: During the COVID-19 pandemic, precisely tracing the route of the SARS-CoV-2 transmission in human population remains challenging. Because this RNA virus can mutate massively without a specifically tracing maker. Herein, using a geographic stratified genome-wide association study (GWAS) of 2599 full-genome sequences, we identified that two SNPs (i.e., 1059.C>T and 25563.G>T) of linkage disequilibrium were presented in approximately half of North America SARS-CoV-2 population (p = 2.44 x 10−212 and p = 2.98 x 10−261), resulting two missense mutations (i.e., Thr 265 Ile and Gln 57 His) in ORF1ab and ORF3a, respectively. Interestingly, these two SNPs exclusively occurred in the North America dominated clade 1, accumulated during mid to late March, 2020. We did not find any of these two SNPs by retrospectively tracing the two SNPs in bat and pangolin related SARS-CoV-2 and human SARS-CoV-2 from the first epicenter Wuhan or other regions of China mainland. This suggested that the SARS-CoV-2 population of Chinese mainland were different from the prevalent strains of North America. Time-dependently, we found that these two SNPs first occurred in Europe SARS-CoV-2 (26-Feb-2020) which was 3 days early than the occurring date of North America isolates and 17 days early for Asia isolates (Taiwan China dominated). Collectively, this population genetic analysis highlights a well-confidential transmission route of the North America isolates and the two SNPs we newly identified are possibly novel diagnosable or druggable targets for surveillance and treatment.

Title: Comparative analyses of SAR-CoV2 genomes from different geographical locations and other coronavirus family genomes reveals unique features potentially consequential to host-virus interaction and pathogenesis Content: The ongoing pandemic of the coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). We have performed an integrated sequence-based analysis of SARS-CoV2 genomes from different geographical locations in order to identify its unique features absent in SARS-CoV and other related coronavirus family genomes, conferring unique infection, facilitation of transmission, virulence and immunogenic features to the virus. The phylogeny of the genomes yields some interesting results. Systematic gene level mutational analysis of the genomes has enabled us to identify several unique features of the SARS-CoV2 genome, which includes a unique mutation in the spike surface glycoprotein (A930V (24351C>T)) in the Indian SARS-CoV2, absent in other strains studied here. We have also predicted the impact of the mutations in the spike glycoprotein function and stability, using computational approach. To gain further insights into host responses to viral infection, we predict that antiviral host-miRNAs may be controlling the viral pathogenesis. Our analysis reveals nine host miRNAs which can potentially target SARS-CoV2 genes. Interestingly, the nine miRNAs do not have targets in SARS and MERS genomes. Also, hsa-miR-27b is the only unique miRNA which has a target gene in the Indian SARS-CoV2 genome. We also predicted immune epitopes in the genomes

Title: Targeting the Dimerization of the Main Protease of Coronaviruses: A Potential Broad-Spectrum Therapeutic Strategy Content: A new coronavirus (CoV) caused a pandemic named COVID-19, which has become a global health care emergency in the present time. The virus is referred to as SARS-CoV-2 (severe acute respiratory syndrome-coronavirus-2) and has a genome similar (â¼82%) to that of the previously known SARS-CoV (SARS coronavirus). An attractive therapeutic target for CoVs is the main protease (Mpro) or 3-chymotrypsin-like cysteine protease (3CLpro), as this enzyme plays a key role in polyprotein processing and is active in a dimeric form. Further, Mpro is highly conserved among various CoVs, and a mutation in Mpro is often lethal to the virus. Thus, drugs targeting the Mpro enzyme significantly reduce the risk of mutation-mediated drug resistance and display broad-spectrum antiviral activity. The combinatorial design of peptide-based inhibitors targeting the dimerization of SARS-CoV Mpro represents a potential therapeutic strategy. In this regard, we have compiled the literature reports highlighting the effect of mutations and N-terminal deletion of residues of SARS-CoV Mpro on its dimerization and, thus, catalytic activity. We believe that the present review will stimulate research in this less explored yet quite significant area. The effect of the COVID-19 epidemic and the possibility of future CoV outbreaks strongly emphasize the urgent need for the design and development of potent antiviral agents against CoV infections.

Title: Genomic Analysis of Early SARS-CoV-2 Variants Introduced in Mexico Content: The COVID-19 pandemic has affected most countries in the world. Studying the evolution and transmission patterns in different countries is crucial to implement effective strategies for disease control and prevention. In this work, we present the full genome sequence for 17 SARS-CoV-2 isolates corresponding to the earliest sampled cases in Mexico. Global and local phylogenomics, coupled with mutational analysis, consistently revealed that these viral sequences are distributed within 2 known lineages, the SARS-CoV-2 lineage A/G, containing mostly sequences from North America, and the lineage B/S containing mainly sequences from Europe. Based on the exposure history of the cases and on the phylogenomic analysis, we characterized fourteen independent introduction events. Additionally, three cases with no travel history were identified. We found evidence that two of these cases represent local transmission cases occurring in Mexico during mid-March 2020, denoting the earliest events described for the country. Within this local transmission cluster, we also identified the H49Y amino acid change in the Spike protein. This mutation is a homoplasy occurring independently through time and space, and may function as a molecular marker to follow on any further spread of these viral variants throughout the country. Our results depict the general picture of the SARS-CoV-2 variants introduced at the beginning of the outbreak in Mexico, setting the foundation for future surveillance efforts.IMPORTANCE Understanding the introduction, spread and establishment of SARS-CoV-2 within distinct human populations is crucial to implement effective control strategies as well as the evolution of the pandemics. In this work, we describe that the initial virus strains introduced in Mexico came from Europe and the United States and the virus was circulating locally in the country as early as mid-March. We also found evidence for early local transmission of strains having the mutation H49Y in the Spike protein, that could be further used as a molecular marker to follow viral spread within the country and the region.

Title: Genomic Analysis of Early SARS-CoV-2 Variants Introduced in Mexico. Content: The COVID-19 pandemic has affected most countries in the world. Studying the evolution and transmission patterns in different countries is crucial to implement effective strategies for disease control and prevention. In this work, we present the full genome sequence for 17 SARS-CoV-2 isolates corresponding to the earliest sampled cases in Mexico. Global and local phylogenomics, coupled with mutational analysis, consistently revealed that these viral sequences are distributed within 2 known lineages, the SARS-CoV-2 lineage A/G, containing mostly sequences from North America, and the lineage B/S containing mainly sequences from Europe. Based on the exposure history of the cases and on the phylogenomic analysis, we characterized fourteen independent introduction events. Additionally, three cases with no travel history were identified. We found evidence that two of these cases represent local transmission cases occurring in Mexico during mid-March 2020, denoting the earliest events described for the country. Within this local transmission cluster, we also identified the H49Y amino acid change in the Spike protein. This mutation is a homoplasy occurring independently through time and space, and may function as a molecular marker to follow on any further spread of these viral variants throughout the country. Our results depict the general picture of the SARS-CoV-2 variants introduced at the beginning of the outbreak in Mexico, setting the foundation for future surveillance efforts.IMPORTANCE Understanding the introduction, spread and establishment of SARS-CoV-2 within distinct human populations is crucial to implement effective control strategies as well as the evolution of the pandemics. In this work, we describe that the initial virus strains introduced in Mexico came from Europe and the United States and the virus was circulating locally in the country as early as mid-March. We also found evidence for early local transmission of strains having the mutation H49Y in the Spike protein, that could be further used as a molecular marker to follow viral spread within the country and the region.

Title: Population genomics insights into the recent evolution of SARS-CoV-2 Content: The current coronavirus disease 2019 (COVID-19) pandemic is caused by the SARS-CoV-2 virus and is still spreading rapidly worldwide. Full-genome-sequence computational analysis of the SARS-CoV-2 genome will allow us to understand the recent evolutionary events and adaptability mechanisms more accurately, as there is still neither effective therapeutic nor prophylactic strategy. In this study, we used population genetics analysis to infer the mutation rate and plausible recombination events that may have contributed to the evolution of the SARS-CoV-2 virus. Furthermore, we localized targets of recent and strong positive selection. The genomic regions that appear to be under positive selection are largely co-localized with regions in which recombination from non-human hosts appeared to have taken place in the past. Our results suggest that the pangolin coronavirus genome may have contributed to the SARS-CoV-2 genome by recombination with the bat coronavirus genome. However, we find evidence for additional recombination events that involve coronavirus genomes from other hosts, i.e., Hedgehog and Sparrow. Even though recombination events within human hosts cannot be directly assessed, due to the high similarity of SARS-CoV-2 genomes, we infer that recombinations may have recently occurred within human hosts using a linkage disequilibrium analysis. In addition, we employed an Approximate Bayesian Computation approach to estimate the parameters of a demographic scenario involving an exponential growth of the size of the SARS-CoV-2 populations that have infected European, Asian and Northern American cohorts, and we demonstrated that a rapid exponential growth in population size can support the observed polymorphism patterns in SARS-CoV-2 genomes.

Title: Translation-associated mutational U-pressure in the first ORF of SARS-CoV-2 and other coronaviruses Content: Within four months of the ongoing COVID-19 pandemic caused by SARS-CoV-2, more than 250 nucleotide mutations have been detected in the ORF1 of the virus isolated from different parts of the globe. These observations open up an obvious question about the rate and direction of mutational pressure for further vaccine and therapeutics designing. In this study, we did a comparative analysis of ORF1a and ORF1b by using the first isolate (Wuhan strain) as the parent sequence. We observed that most of the nucleotide mutations are C to U transitions. The rate of synonymous C to U transitions is significantly higher than the rate of nonsynonymous ones, indicating negative selection on amino acid substitutions. Further, trends in nucleotide usage bias have been investigated in 49 coronaviruses species. A strong bias in nucleotide usage in fourfold degenerated sites towards uracil residues is seen in ORF1 of all the studied coronaviruses. A more substantial mutational U pressure is observed in ORF1a than in ORF1b owing to the translation of ORF1ab via programmed ribosomal frameshifting. Unlike other nucleotide mutations, mutational U pressure caused by cytosine deamination, mostly occurring in the RNA-plus strand, cannot be corrected by the proof-reading machinery of coronaviruses. The knowledge generated on the direction of mutational pressure during translation of viral RNA-plus strands has implications for vaccine and nucleoside analogue development for treating covid-19 and other coronavirus infections.

Title: Genome-wide analysis of Indian SARS-CoV-2 genomes for the identification of genetic mutation and SNP Content: The wave of COVID-19 is a big threat to the human population. Presently, the world is going through different phases of lock down in order to stop this wave of pandemic; India being no exception. We have also started the lock down on 23rd March 2020. In this current situation, apart from social distancing only a vaccine can be the proper solution to serve the population of human being. Thus it is important for all the nations to perform the genome-wide analysis in order to identify the genetic variation in Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) so that proper vaccine can be designed. This fast motivated us to analyze publicly available 566 Indian complete or near complete SARS-CoV-2 genomes to find the mutation points as substitution, deletion and insertion. In this regard, we have performed the multiple sequence alignment in presence of reference sequence from NCBI. After the alignment, a consensus sequence is build to analyze each genome in order to identify the mutation points. As a consequence, we have found 933 substitutions, 2449 deletions and 2 insertions, in total 3384 unique mutation points, in 566 genomes across 29.9 K bp. Further, it has been classified into three groups as 100 clusters of mutations (mostly deletions), 1609 point mutations as substitution, deletion and insertion and 64 SNPs. These outcomes are visualized using BioCircos and bar plots as well as plotting entropy value of each genomic location. Moreover, phylogenetic analysis has also been performed to see the evolution of SARS-CoV-2 virus in India. It also shows the wide variation in tree which indeed vivid in genomic analysis. Finally, these SNPs can be the useful target for virus classification, designing and defining the effective dose of vaccine for the heterogeneous population.

Title: Hidden genomic diversity of SARS-CoV-2: implications for qRT-PCR diagnostics and transmission Content: The COVID-19 pandemic has sparked an urgent need to uncover the underlying biology of this devastating disease. Though RNA viruses mutate more rapidly than DNA viruses, there are a relatively small number of single nucleotide polymorphisms (SNPs) that differentiate the main SARS-CoV-2 clades that have spread throughout the world. In this study, we investigated over 7,000 SARS-CoV-2 datasets to unveil both intrahost and interhost diversity. Our intrahost and interhost diversity analyses yielded three major observations. First, the mutational profile of SARS-CoV-2 highlights iSNV and SNP similarity, albeit with high variability in C>T changes. Second, iSNV and SNP patterns in SARS-CoV-2 are more similar to MERS-CoV than SARS-CoV-1. Third, a significant fraction of small indels fuel the genetic diversity of SARS-CoV-2. Altogether, our findings provide insight into SARS-CoV-2 genomic diversity, inform the design of detection tests, and highlight the potential of iSNVs for tracking the transmission of SARS-CoV-2.

Title: coronapp: A Web Application to Annotate and Monitor SARS-CoV-2 Mutations Content: The avalanche of genomic data generated from the SARS-CoV-2 virus requires the development of tools to detect and monitor its mutations across the World. Here, we present a webtool, coronapp, dedicated to easily processing user-provided SARS-CoV-2 genomic sequences, in order to detect and annotate protein-changing mutations. This results in an up-to-date status of SARS-CoV-2 mutations, both worldwide and in user-selected countries. The tool allows users to highlight and prioritize the most frequent mutations in specific protein regions, and to monitor their frequency in the population over time. The tool is available at http://giorgilab.dyndns.org/coronapp/ and the full code is freely shared at https://github.com/federicogiorgi/giorgilab/tree/master/coronapp

Title: Mechanisms of Host Receptor Adaptation by Severe Acute Respiratory Syndrome Coronavirus Content: The severe acute respiratory syndrome coronavirus (SARS-CoV) from palm civets has twice evolved the capacity to infect humans by gaining binding affinity for human receptor angiotensin-converting enzyme 2 (ACE2). Numerous mutations have been identified in the receptor-binding domain (RBD) of different SARS-CoV strains isolated from humans or civets. Why these mutations were naturally selected or how SARS-CoV evolved to adapt to different host receptors has been poorly understood, presenting evolutionary and epidemic conundrums. In this study, we investigated the impact of these mutations on receptor recognition, an important determinant of SARS-CoV infection and pathogenesis. Using a combination of biochemical, functional, and crystallographic approaches, we elucidated the molecular and structural mechanisms of each of these naturally selected RBD mutations. These mutations either strengthen favorable interactions or reduce unfavorable interactions with two virus-binding hot spots on ACE2, and by doing so, they enhance viral interactions with either human (hACE2) or civet (cACE2) ACE2. Therefore, these mutations were viral adaptations to either hACE2 or cACE2. To corroborate the above analysis, we designed and characterized two optimized RBDs. The human-optimized RBD contains all of the hACE2-adapted residues (Phe-442, Phe-472, Asn-479, Asp-480, and Thr-487) and possesses exceptionally high affinity for hACE2 but relative low affinity for cACE2. The civet-optimized RBD contains all of the cACE2-adapted residues (Tyr-442, Pro-472, Arg-479, Gly-480, and Thr-487) and possesses exceptionally high affinity for cACE2 and also substantial affinity for hACE2. These results not only illustrate the detailed mechanisms of host receptor adaptation by SARS-CoV but also provide a molecular and structural basis for tracking future SARS-CoV evolution in animals.

Title: Genotyping coronavirus SARS-CoV-2: methods and implications Content: The emerging global infectious COVID-19 coronavirus disease by novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) presents critical threats to global public health and the economy since it was identified in late December 2019 in China. The virus has gone through various pathways of evolution. For understanding the evolution and transmission of SARS-CoV-2, genotyping of virus isolates is of great importance. We present an accurate method for effectively genotyping SARS-CoV-2 viruses using complete genomes. The method employs the multiple sequence alignments of the genome isolates with the SARS-CoV-2 reference genome. The SNP genotypes are then measured by Jaccard distances to track the relationship of virus isolates. The genotyping analysis of SARS-CoV-2 isolates from the globe reveals that specific multiple mutations are the predominated mutation type during the current epidemic. Our method serves a promising tool for monitoring and tracking the epidemic of pathogenic viruses in their gradual and local genetic variations. The genotyping analysis shows that the genes encoding the S proteins and RNA polymerase, RNA primase, and nucleoprotein, undergo frequent mutations. These mutations are critical for vaccine development in disease control.

Title: RdRp mutations are associated with SARS-CoV-2 genome evolution Content: COVID-19, caused by the novel SARS-CoV-2 virus, started in China in late 2019, and soon became a global pandemic. With the help of thousands of viral genome sequences that have been accumulating, it has become possible to track the evolution of viral genome over time as it spread across the world. An important question that still needs to be answered is whether any of the common mutations affect the viral properties, and therefore the disease characteristics. Therefore, we sought to understand the effects of mutations in RNA-dependent RNA polymerase (RdRp), particularly the common 14408C>T mutation, on mutation rate and viral spread. By focusing on mutations in the slowly evolving M or E genes, we aimed to minimize the effects of selective pressure. Our results indicate that 14408C>T mutation increases the mutation rate, while the third-most common RdRp mutation, 15324C>T, has the opposite effect. It is possible that 14408C>T mutation may have contributed to the dominance of its co-mutations in Europe and elsewhere.

Title: Targeting the Dimerization of the Main Protease of Coronaviruses: A Potential Broad-Spectrum Therapeutic Strategy Content: [Image: see text] A new coronavirus (CoV) caused a pandemic named COVID-19, which has become a global health care emergency in the present time. The virus is referred to as SARS-CoV-2 (severe acute respiratory syndrome-coronavirus-2) and has a genome similar (∼82%) to that of the previously known SARS-CoV (SARS coronavirus). An attractive therapeutic target for CoVs is the main protease (M(pro)) or 3-chymotrypsin-like cysteine protease (3CL(pro)), as this enzyme plays a key role in polyprotein processing and is active in a dimeric form. Further, M(pro) is highly conserved among various CoVs, and a mutation in M(pro) is often lethal to the virus. Thus, drugs targeting the M(pro) enzyme significantly reduce the risk of mutation-mediated drug resistance and display broad-spectrum antiviral activity. The combinatorial design of peptide-based inhibitors targeting the dimerization of SARS-CoV M(pro) represents a potential therapeutic strategy. In this regard, we have compiled the literature reports highlighting the effect of mutations and N-terminal deletion of residues of SARS-CoV M(pro) on its dimerization and, thus, catalytic activity. We believe that the present review will stimulate research in this less explored yet quite significant area. The effect of the COVID-19 epidemic and the possibility of future CoV outbreaks strongly emphasize the urgent need for the design and development of potent antiviral agents against CoV infections.

Title: Genotyping coronavirus SARS-CoV-2: Methods and implications Content: Abstract The emerging global infectious COVID-19 disease by novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) presents critical threats to global public health and the economy since it was identified in late December 2019 in China. The virus has gone through various pathways of evolution. To understand the evolution and transmission of SARS-CoV-2, genotyping of virus isolates is of great importance. This study presents an accurate method for effectively genotyping SARS-CoV-2 viruses using complete genomes. The method employs the multiple sequence alignments of the genome isolates with the SARS-CoV-2 reference genome. The single-nucleotide polymorphism (SNP) genotypes are then measured by Jaccard distances to track the relationship of virus isolates. The genotyping analysis of SARS-CoV-2 isolates from the globe reveals that specific multiple mutations are the predominated mutation type during the current epidemic. The proposed method serves an effective tool for monitoring and tracking the epidemic of pathogenic viruses in their global and local genetic variations. The genotyping analysis shows that the genes encoding the S proteins and RNA polymerase, RNA primase, and nucleoprotein, undergo frequent mutations. These mutations are critical for vaccine development in disease control.

Title: Genotyping coronavirus SARS-CoV-2: methods and implications Content: The emerging global infectious COVID-19 disease by novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) presents critical threats to global public health and the economy since it was identified in late December 2019 in China. The virus has gone through various pathways of evolution. To understand the evolution and transmission of SARS-CoV-2, genotyping of virus isolates is of great importance. This study presents an accurate method for effectively genotyping SARS-CoV-2 viruses using complete genomes. The method employs the multiple sequence alignments of the genome isolates with the SARS-CoV-2 reference genome. The single-nucleotide polymorphism (SNP) genotypes are then measured by Jaccard distances to track the relationship of virus isolates. The genotyping analysis of SARS-CoV-2 isolates from the globe reveals that specific multiple mutations are the predominated mutation type during the current epidemic. The proposed method serves an effective tool for monitoring and tracking the epidemic of pathogenic viruses in their global and local genetic variations. The genotyping analysis shows that the genes encoding the S proteins and RNA polymerase, RNA primase, and nucleoprotein, undergo frequent mutations. These mutations are critical for vaccine development in disease control.

Title: Time-series analyses of directional sequence changes in SARS-CoV-2 genomes and an efficient search method for advantageous mutations for growth in human cells Content: We first conducted time-series analysis of mono- and dinucleotide composition for over 10,000 SARS-CoV-2 genomes, as well as over 1500 Zaire ebolavirus genomes, and found clear time-series changes in the compositions on a monthly basis, which should reflect viral adaptations for efficient growth in human cells. We next developed a sequence alignment free method that extensively searches for advantageous mutations and rank them in an increase level for their intrapopulation frequency. Time-series analysis of occurrences of oligonucleotides of diverse lengths for SARS-CoV-2 genomes revealed seven distinctive mutations that rapidly expanded their intrapopulation frequency and are thought to be candidates of advantageous mutations for the efficient growth in human cells.

Title: Failure of the cobas(R) SARS-CoV-2 (Roche) E-gene assay is associated with a C-to-T transition at position 26340 of the SARS-CoV-2 genome Content: Control of the ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic requires accurate laboratory testing to identify infected individuals, while also clearing essential staff to continue work. At the current time a number of RT-PCR tests have been developed to identify SARS-CoV-2, targeting multiple regions in the viral genome. In comparison to other RNA viruses the mutation rate of SARS-CoV-2 is moderate, however given the large number of transmission chains it is prudent to monitor circulating viruses for mutations that might compromise these tests. Here we report the identification of a C-to-T transition at position 26340 of the SARS-CoV-2 genome which is associated with failure of the cobas(R) SARS-CoV-2 E-gene assay. This variant was detected in four health care workers from the same team. Whole genome sequencing of SARS-CoV-2 showed all four to carry genetically identical viruses. Examination of viral genomes deposited on GISAID showed this mutation has arisen independently on three occasions. This work highlights the necessity of monitoring SARS-CoV-2 for the emergence of SNPs which might adversely affect the RT-PCRs used in diagnostics. Additionally, it argues that two regions in the SARS-CoV-2 should be targeted in RT-PCRs to avoid false negatives.

Title: Analysis of SARS-CoV-2 Genomes from Southern California Reveals Community Transmission Pathways in the Early Stage of the US COVID-19 Pandemic Content: Given the higher mortality rate and widespread phenomenon of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) within the United States (US) population, understanding the mutational pattern of SARS CoV-2 has global implications for detection and therapy to prevent further escalation. Los Angeles has become an epicenter of the SARS-CoV-2 pandemic in the US. Efforts to contain the spread of SARS-CoV-2 require identifying its genetic and geographic variation and understanding the drivers of these differences. For the first time, we report genetic characterization of SARS-CoV-2 genome isolates in the Los Angeles population using targeted next generation sequencing (NGS). Samples collected at Cedars Sinai Medical Center were collected from patients with confirmed SARS-CoV-2 infection. We identified and diagnosed 192 patients by our in-house qPCR assay. In this population, the highest frequency variants were in known mutations in the 5'UTR, AA193 protein, RdRp and the spike glycoprotein. SARS-CoV-2 transmission within the local community was tracked by integrating mutation data with patient postal codes with two predominant community spread clusters being identified. Notably, significant viral genomic diversity was identified. Less than 10 percent of the Los Angeles community samples resembled published mutational profiles of SARS-CoV-2 genomes from China, while >50 percent of the isolates shared closely similarities to those from New York State. Based on these findings we conclude SARS-CoV-2 was likely introduced into the Los Angeles community predominantly from New York State but also via multiple other independent transmission routes including but not limited to Washington State and China.

Title: Genomic analysis of early SARS-CoV-2 strains introduced in Mexico Content: The COVID-19 pandemic has affected most countries in the world. Studying the evolution and transmission patterns in different countries is crucial to implement effective strategies for disease control and prevention. In this work, we present the full genome sequence for 17 SARS-CoV-2 isolates corresponding to the earliest sampled cases in Mexico. Global and local phylogenomics, coupled with mutational analysis, consistently revealed that these viral sequences are distributed within 2 known lineages, the SARS-CoV-2 lineage A/G, containing mostly sequences from North America, and the lineage B/S containing mainly sequences from Europe. Based on the exposure history of the cases and on the phylogenomic analysis, we characterized fourteen independent introduction events. Additionally, three cases with no travel history were identified. We found evidence that two of these cases represent local transmission cases occurring in Mexico during mid-March 2020, denoting the earliest events described in the country. Within this Mexican cluster, we also identified an H49Y amino acid change in the spike protein. This mutation is a homoplasy occurring independently through time and space, and may function as a molecular marker to follow on any further spread of these viral variants throughout the country. Our results depict the general picture of the SARS-CoV-2 variants introduced at the beginning of the outbreak in Mexico, setting the foundation for future surveillance efforts. This work is the result of the collaboration of five institutions into one research consortium: three public health institutes and two universities. From the beginning of this work, it was agreed that the experimental leader of each institution would share the first authorship. Those were the criteria followed to assign first co-first authorship in this manuscript. The order of the other authors was randomly assigned. IMPORTANCE Understanding the introduction, spread and establishment of SARS-CoV-2 within distinct human populations is crucial to implement effective control strategies as well as the evolution of the pandemics. In this work, we describe that the initial virus strains introduced in Mexico came from Europe and the United States and the virus was circulating locally in the country as early as mid-March. We also found evidence for early local transmission of strains having the mutation H49Y in the Spike protein, that could be further used as a molecular marker to follow viral spread within the country and the region.

Title: Complexity in SARS-CoV-2 genome data: Price theory of mutant isolates Content: SARS-CoV-2 is a highly virulent and deadly RNA virus causing the Covid-19 pandemic and several deaths across the world. The pandemic is so fast that any concrete theory of sudden widespread of this disease is still not known. In this work, we studied and analyzed a large number of publicly available SARS-CoV-2 genomes across the world using the multifractal approach. The mutation events in the isolates obey the Markov process and exhibit very high mutational rates, which occur in six specific genes and highest in orf1ab gene, leading to virulent nature. f (α) analysis indicated that the isolates are highly asymmetric (left-skewed), revealing the richness of complexity and dominance by large fluctuations in genome structure organization. The values of Hq and Dq are found to be significantly large, showing heterogeneous genome structure self-organization, strong positive correlation in organizing the isolates, and quite sensitive to fluctuations in and around it. We then present multiple-isolates hosts-virus interaction models, and derived Price equation for the model. The phase plane analysis of the model showed asymptotic stability type bifurcation. The competition among the mutant isolates drives the trade-off of the dominant mutant isolates, otherwise confined to the present hosts.

Title: Multiple assays in a real-time RT-PCR SARS-CoV-2 panel can mitigate the risk of loss of sensitivity by new genomic variants during the COVID-19 outbreak Content: OBJECTIVES: In this study, five SARS-CoV-2 PCR assay panels were evaluated against the accumulated genetic variability of the virus to assess the effect on sensitivity of the individual assays. DESIGN OR METHODS: As of week 21, 2020, the complete set of available SARS-CoV-2 genomes from GISAID and GenBank databases were used in this study. SARS-CoV-2 primer sequences from publicly available panels (WHO, CDC, NMDC, and HKU) and QIAstat-Dx were included in the alignment, and accumulated genetic variability affecting any oligonucleotide annealing was annotated. RESULTS: A total of 11,627 (34.38%) genomes included single mutations affecting annealing of any PCR assay. Variations in 8,773 (25.94%) genomes were considered as high risk, whereas additional 2,854 (8.43%) genomes presented low frequent single mutations and were predicted to yield no impact on sensitivity. In case of the QIAstat-Dx SARS-CoV-2 Panel, 99.11% of the genomes matched with a 100% coverage all oligonucleotides, and critical variations were tested in vitro corroborating no loss of sensitivity. CONCLUSIONS: This analysis stresses the importance of targeting more than one region in the viral genome for SARS-CoV-2 detection to mitigate the risk of loss of sensitivity due to the unknown mutation rate during this SARS-CoV-2 outbreak.

Title: Large-Scale Phylogenetic Analysis of Emerging Infectious Diseases Content: Microorganisms that cause infectious diseases present critical issues of national security, public health, and economic welfare. For example, in recent years, highly pathogenic strains of avian influenza have emerged in Asia, spread through Eastern Europe, and threaten to become pandemic. As demonstrated by the coordinated response to Severe Acute Respiratory Syndrome (SARS) and influenza, agents of infectious disease are being addressed via large-scale genomic sequencing. The goal of genomic sequencing projects are to rapidly put large amounts of data in the public domain to accelerate research on disease surveillance, treatment, and prevention. However, our ability to derive information from large comparative genomic datasets lags far behind acquisition. Here we review the computational challenges of comparative genomic analyses, specifically sequence alignment and reconstruction of phylogenetic trees. We present novel analytical results on two important infectious diseases, Severe Acute Respiratory Syndrome (SARS) and influenza. SARS and influenza have similarities and important differences both as biological and comparative genomic analysis problems. Influenza viruses (Orthymxyoviridae) are RNA based. Current evidence indicates that influenza viruses originate in aquatic birds from wild populations. Influenza has been studied for decades via well-coordinated international efforts. These efforts center on surveillance via antibody characterization of the hemagglutinin (HA) and neuraminidase (N) proteins of the circulating strains to inform vaccine design. However, we still do not have a clear understanding of (1) various transmission pathways such as the role of intermediate hosts like swine and domestic birds and (2) the key mutation and genomic recombination events that underlie periodic pandemics of influenza. In the past 30 years, sequence data from HA and N loci has become an important data type. In the past year, full genomic data has become prominent. These data present exciting opportunities to address unanswered questions in influenza pandemics. SARS is caused by a previously unrecognized lineage of coronavirus, SARS-CoV, which like influenza has an RNA based genome. Although SARS-CoV is widely believed to have originated in animals, there remains disagreement over the candidate animal source that lead to the original outbreak of SARS. In contrast to the long history of the study of influenza, SARS was only recognized in late 2002 and the virus that causes SARS has been documented primarily by genomic sequencing. In the past, most studies of influenza were performed on a limited number of isolates and genes suited to a particular problem. Major goals in science today are to understand emerging diseases in broad geographic, environmental, societal, biological, and genomic contexts. Synthesizing diverse information brought together by various researchers is important to find out what can be done to prevent future outbreaks [JON03]. Thus comprehensive means to organize and analyze large amounts of diverse information are critical. For example, the relationships of isolates and patterns of genomic change observed in large datasets might not be consistent with hypotheses formed on partial data. Moreover when researchers rely on partial datasets, they restrict the range of possible discoveries. Phylogenetics is well suited to the complex task of understanding emerging infectious disease. Phylogenetic analyses can test many hypotheses by comparing diverse isolates collected from various hosts, environments, and points in time and organizing these data into various evolutionary scenarios. The products of a phylogenetic analysis are a graphical tree of ancestor–descendent relationships and an inferred summary of mutations, recombination events, host shifts, geographic, and temporal spread of the viruses. However, this synthesis comes at a price. The cost of computation of phylogenetic analysis expands combinatorially as the number of isolates considered increases. Thus, large datasets like those currently produced are commonly considered intractable. We address this problem with synergistic development of heuristics tree search strategies and parallel computing.

Title: Characterization of the substitution hotspots in SARS-CoV-2 genome using BioAider and detection of a SR-rich region in N protein providing further evidence of its animal origin Content: The novel human coronavirus (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19) pandemic worldwide. The increasing sequencing data have shown abundant single nucleotide variations in SARS-CoV-2 genome. However, it is difficult to quickly analyze genomic variation and screen key mutations of SARS-CoV-2. In this study, we developed a visual program, named BioAider, for quick and convenient sequence annotation and mutation analysis on multiple genome-sequencing data. Using BioAider, we conducted a comprehensive genome variation analysis on 3,240 sequences of SARS-CoV-2 genome. Herein, we detected 14 substitution hotspots within SARS-CoV-2 genome, including 10 non-synonymous and 4 synonymous ones. Among these hotspots, NSP13-Y541C was predicted to be a crucial substitution which might affect the unwinding activity of NSP13, a key protein for viral replication. Besides, we also found 3 groups of potentially linked substitution hotspots which were worth further study. In particular, we discovered a SR-rich region (aa 184-204) on the N protein of SARS-CoV-2 distinct from SARS-CoV, indicating more complex replication mechanism and unique N-M interaction of SARS-CoV-2. Interestingly, the quantity of SRXX repeat fragments in the SR-rich region well reflected the evolutionary relationship among SARS-CoV-2 and SARS-CoV-2 related animal coronaviruses, providing further evidence of its animal origin. Overall, we developed an efficient tool for rapid identification of mutations, identified substitution hotspots in SARS-CoV-2 genomes, and detected a distinctive polymorphism SR-rich region in N protein. This tool and the detected hotspots could facilitate the viral genomic study and may contribute for screening antiviral target sites.

Title: Genomic Mutations and Changes in Protein Secondary Structure and Solvent Accessibility of SARS-CoV-2 (COVID-19 Virus) Content: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly pathogenic virus that has caused the global COVID-19 pandemic. Tracing the evolution and transmission of the virus is crucial to respond to and control the pandemic through appropriate intervention strategies. This paper reports and analyses genomic mutations in the coding regions of SARS-CoV-2 and their probable protein secondary structure and solvent accessibility changes, which are predicted using deep learning models. Prediction results suggest that mutation D614G in the virus spike protein, which has attracted much attention from researchers, is unlikely to make changes in protein secondary structure and relative solvent accessibility. Based on 6,324 viral genome sequences, we create a spreadsheet dataset of point mutations that can facilitate the investigation of SARS-CoV-2 in many perspectives, especially in tracing the evolution and worldwide spread of the virus. Our analysis results also show that coding genes E, M, ORF6, ORF7a, ORF7b and ORF10 are most stable, potentially suitable to be targeted for vaccine and drug development.