# SARS-CoV-2 (COVID-19): New Discoveries and Current Challenges
## 2 Genomics and Virology
Four additional full-length genome sequences of COVID-19 (WIV02, WIV05, WIV06, and WIV07) (GISAID accession numbers EPI_ISL_402127-402130) were found to be over 99.9% indistinguishable from each other and were acquired from four extra cases of patients applying next-generation sequencing and PCR [29]. [PERSON] and co-workers made phylogenetic investigation on the total viral genome and reasoned that the infection was very intensely identified with a gathering of SARS-like coronavirus recently examined from bats in China [30]. In another study, extensive sequence evaluation was performed, and correlation connected to relative synonymous codon usage (RSCU) inclination among various creature species dependent on the COVID-19 RNA genome sequence [4]. The outcomes revealed the infection to be a recombinant infection among the bat coronavirus and an additional coronavirus of obscure inception. Additionally, they proposed that snake is the most plausible creature repository because of the infection's RSCU predisposition being nearest to snake. Furthermore, [PERSON] and associates utilized profound  
Figure 4: \(\beta\)-CoVs lineage B entry with angiotensin-converting enzyme 2 (ACE2) is clade specific: (**a**) \(\beta\)-CoVs, comprising SARS-CoV, interact with the host–cell receptor through the receptor-binding domain (RBD) in spike (Protein Data Bank ID: 5X5B; 2 AJF), (**b**) Engineered silent mutations in SARS-spike eased replacement of the RBD sequence. SARS-spike amino acid numbers are designated in black towards the silent cloning sites or orange for the RBD, (**c**) The experimental workflow outline, (**d**) Western blot of creator cell lysates and concentrated reporter particles. The labels along the top illustrate the origin of the RBD in the SARS-CoV spike protein, (**e**) Cladogram of the 29 spikes tested. The data are representative of 3 technical replicates. Vertical bars indicate mean values of all three replicates and horizontal bars indicate s.d. Reproduced with permission from Ref. [28]. learning calculations to investigate the gene sequences of new CoVs and the other different ones to foresee prospective viral hosts [31]. The conclusions showed that minks and bats might be the two likely hosts of the new coronavirus, while minks might be the transitional/intermediate hosts of the infection. The new coronavirus indicated a comparative pattern of disease to different CoVs in humans [31], especially Bat SARS-like CoV, SARS-nCoV, and MERS-nCoV [32]. Subsequent to scrutinizing of CoVs in different vertebrates, it was found that the bat CoVs had the most similar/comparative infection patterns to the new CoVs. In the wake of studying the infection patterns of other vertebrate coronavirus hosts, the prototypes from minks were observed as most similar to those of the new coronavirus [31]. By displaying the spike protein of the receptor for COVID-19, [PERSON] et al. [33] detailed that ACE2 could be the receptor for this virus. Notably, ACE2 has also been the receptor for SARS-nCoV and NL63 [34]. As per their model, the binding strength between COVID-19 and ACE2 is higher than the limit required for viral infection disease but being more vulnerable than that between SARS-nCoV and ACE2. [PERSON] et al. [2] directed the virus infectivity considerations and indicated that ACE2 is basic for COVID-19 to go in the HeLa cells. This information showed that ACE2 is probably going to be the receptor for COVID-19. Furthermore, [PERSON] et al. [35] investigated normal lung tissue cells from eight people, and found that the main Asian donor has more than fivefold the amount of ACE2 expressing cell ratio than African American and White cases. These outcomes point to a potential increased susceptibility of Asian populace, albeit more proof is expected to reach such a determination.