bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermostability of mouse-passaged BSE and scrapie is independent of host PrP genotype: implications for the nature of the causal agents
Authors: Taylor David M. , Fernie Karen , Steele Philip J. , McConnell Irene , Somerville Robert A. 
Published: August 2015

Five experimentally maintained strains of scrapie and BSE agents have been passaged in two PrP genotypes of mice. Brain macerates were autoclaved at 126 °C and the levels of surviving infectivity were measured by titration. There was a large difference in the survival properties of transmissible spongiform encephalopathy (TSE) infectivity between TSE strains. PrP genotype had little effect. Phenotypic properties of the TSE strains were not affected with the exception that with one strain (ME7), incubation periods of the heated sample were longer than the controls given equivalent doses. It is concluded that PrP is probably not responsible for differences in thermostability between strains. More likely, a host-independent molecule which differs in covalent structure between strains accounts for these properties.
Replacing the SCR domains of vaccinia virus protein B5R with EGFP causes a reduction in plaque size and actin tail formation but enveloped virions are still transported to the cell surface
Authors: Rodger Gaener , Smith Geoffrey L. 
Published: August 2015

A vaccinia virus (VV) recombinant is described in which the outer envelope of extracellular enveloped virus (EEV), cell-associated enveloped virus (CEV) and intracellular enveloped virus (IEV) is labelled with the enhanced green fluorescent protein (EGFP) derived fromAequorea victoria. To construct this virus, EGFP was fused to the VV B5R protein from which the four short consensus repeats (SCRs) of the extracellular domain had been deleted. Cells infected with the recombinant virus expressed a B5R–EGFP fusion protein of 40 kDa that was present on IEV, CEV and EEV, but was absent from IMV. The recombinant virus produced 2- and 3-fold reduced levels of IMV and EEV, respectively. Analysis of infected cells by confocal microscopy showed that actin tail formation by the mutant virus was reduced by 86% compared to wild-type (WT). The virus formed a small plaque compared to WT, consistent with a role for actin tails in promoting cell-to-cell spread of virus. However, the enveloped virions were still transported to the cell surface, confirming that this process is independent of actin tail formation. Lastly, we compared the mutant virus with a recombinant VV in which the B5R SCR domains were deleted and show that, contrary to a previous report, the plaque size of the latter virus was reduced compared to WT. This observation reconciles an inconsistency in the field and confirms that viruses deficient in formation of actin tails form small plaques.
Defective segment 1 RNAs that interfere with production of infectious influenza A virus require at least 150 nucleotides of 5′ sequence: evidence from a plasmid-driven system
Authors: Duhaut S. D. , Dimmock N. J. 
Published: August 2015

The presence of at least 80–90 and more typically around 200 nucleotides (nt) at the 5′ end of the virion-sense RNA in all naturally occurring defective influenza A virus RNAs suggests that this is essential sequence, whereas the 3′-end sequence may be as short as 25 nt. The stability of defective RNA on serial passage with infectious helper virus also depends on the length of 5′-end sequence. Here, we have studied the influence of 5′-end sequences of a panel of six defective segment 1 RNAs from H3N8 and H7N7 viruses on their ability to interfere with the multiplication of plasmid-produced infectious A/WSN virus (H1N1). Four of the H3N8 defective RNAs are identical in overall length but vary in the length of 5′ sequence. Transfected defective RNAs interfered with infectious virus production in a concentration-dependent manner. The extent of interference also depended on the length of 5′-end sequence in the defective genome. This required at least 150 nt and was maximal with 220 nt of 5′ end sequence. The reduction in virus multiplication was highly significant and correlated with the presence of detectable intracellular defective RNA. Packaging of full-length segment 1 RNA by progeny virus was inversely proportional to the packaging of defective segment 1 RNA and may explain the reduction in infectivity. In summary, a critical length of 5′-end sequence is essential for the interfering properties of defective influenza virus RNAs, which indicates that this plays some vital role in the virus life cycle.
Linkage on chromosome 10 of several murine retroviral integration loci associated with leukaemia
Authors: Haviernik Peter , Festin Stephen M. , Opavsky Rene , Koller Richard P. , Barr Nighean I. , Neil James C. , Wolff Linda 
Published: August 2015

Mmlloci have been identified as provirus integration sites among a subset of monocytic tumours induced by murine leukaemia virus (MuLV) infection of BALB/c and DBA/2 mice. These myeloid leukaemias contain a retrovirus integrated on chromosome 10 in proximity to the c-myblocus; however, c-mybexpression was not altered. Detailed physical mapping enabled placement of the retroviral integration sites ∼25 kb (Mml1), ∼51 kb (Mml2), and ∼70 kb (Mml3) upstream of the c-myblocus. Furthermore, theFti1 (fit-1) locus, a common integration site in feline leukaemia virus-induced T cell lymphomas, was mapped upstream ofMml3. Sequence analysis ofMml1,Mml2 andMml3 loci (39·6, 16·4 and 5·9 kb, respectively) in conjunction with the BLAST (basic local alignment search tool) homology searches against the expressed sequence tag (EST) database and the use of gene/exon prediction programs revealed potential coding sequences that were not confirmed by Northern analysis or RT–PCR. The sequences between c-mybandFti1, which were shown to include two potential scaffold/matrix attachment regions (S/MARs), are most likely regulatory in nature. An extended search for transcribed sequences far upstream ofMml3 revealed five genes, four of which were expressed in multiple tissues in mice. These genes could not be linked to tumour formation by the virus but their homologous sequences were found on human chromosome 6, thus allowing extension of the syntenic region on mouse chromosome 10 to approximately 250 kb.
Human herpesvirus-6 rep/U94 gene product has single-stranded DNA-binding activity
Authors: Dhepakson Panadda , Mori Yasuko , Jiang Yun Bao , Huang Hong Lan , Akkapaiboon Pilailuk , Okuno Toshiomi , Yamanishi Koichi 
Published: August 2015

The characterization is reported of the human herpesvirus-6B (HHV-6B) rep/U94 gene, which is a homologue of the adeno-associated virus type 2 rep. In this study, a monoclonal antibody was produced against HHV-6B REP (anti-REP mAb). Immunofluorescence staining using the anti-REP mAb showed that REP was localized to the nucleus in HHV-6-infected MT4 cells. It was first detected at 24 h post-infection (p.i.) and accumulated to higher levels by 72 h p.i. REP may be expressed only at very low levels in HHV-6-infected cells: even when the late protein glycoprotein H was detected in nearly 90% of HHV-6-infected cells, REP was detected in only a small percentage of them. Western blot analysis showed that the anti-REP mAb recognized a 56-kDa polypeptide in HHV-6B-infected MT4 cells. Furthermore, the REP protein was shown to bind single-stranded DNA.
The sequence of camelpox virus shows it is most closely related to variola virus, the cause of smallpox
Authors: Gubser Caroline , Smith Geoffrey L. 
Published: August 2015

Camelpox virus (CMPV) and variola virus (VAR) are orthopoxviruses (OPVs) that share several biological features and cause high mortality and morbidity in their single host species. The sequence of a virulent CMPV strain was determined; it is 202182 bp long, with inverted terminal repeats (ITRs) of 6045 bp and has 206 predicted open reading frames (ORFs). As for other poxviruses, the genes are tightly packed with little non-coding sequence. Most genes within 25 kb of each terminus are transcribed outwards towards the terminus, whereas genes within the centre of the genome are transcribed from either DNA strand. The central region of the genome contains genes that are highly conserved in other OPVs and 87 of these are conserved in all sequenced chordopoxviruses. In contrast, genes towards either terminus are more variable and encode proteins involved in host range, virulence or immunomodulation. In some cases, these are broken versions of genes found in other OPVs. The relationship of CMPV to other OPVs was analysed by comparisons of DNA and predicted protein sequences, repeats within the ITRs and arrangement of ORFs within the terminal regions. Each comparison gave the same conclusion: CMPV is the closest known virus to variola virus, the cause of smallpox.
The vaccinia virus B9R protein is a 6 kDa intracellular protein that is non-essential for virus replication and virulence
Authors: Price Nicola , Tscharke David C. , Smith Geoffrey L. 
Published: August 2015

Vaccinia virus (VV) strain Western Reserve gene B9R is shown to encode an intracellular 6 kDa protein that is expressed late during the infectious cycle.In vitrotranscription and translation produced two polypeptides in the presence of microsomal membranes, but only the larger protein in the absence of membranes. The smaller protein sedimented with microsomes during centrifugation, suggesting it was inserted into the lipid membrane or into the microsomal lumen via the N-terminal hydrophobic signal sequence that was subsequently cleaved proteolytically. A VV mutant lacking B9R was constructed and found to replicate normally in cell culture and twoin vivomodels.
Characterization of plant proteins that interact with cowpea mosaic virus ‘60K’ protein in the yeast two-hybrid system
Authors: Carette Jan E. , Verver Jan , Martens Joost , van Kampen Tony , Wellink Joan , van Kammen Ab 
Published: August 2015

Cowpea mosaic virus (CPMV) replication occurs in close association with small membranous vesicles in the host cell. The CPMV RNA1-encoded 60 kDa nucleotide-binding protein (‘60K’) plays a role in the formation of these vesicles. In this study, five cellular proteins were identified that interacted with different domains of 60K using a yeast two-hybrid search of anArabidopsiscDNA library. Two of these host proteins (termed VAP27-1 and VAP27-2), with high homology to the VAP33 family of SNARE-like proteins from animals, interacted specifically with the C-terminal domain of 60K and upon transient expression colocalized with 60K in CPMV-infected cowpea protoplasts. eEF1-β, picked up using the central domain of 60K, was also found to colocalize with 60K. The possible role of these host proteins in the viral replicative cycle is discussed.
Shrimp Taura syndrome virus: genomic characterization and similarity with members of the genus Cricket paralysis-like viruses
Authors: Mari Jocelyne , Poulos Bonnie T. , Lightner Donald V. , Bonami Jean-Robert 
Published: August 2015

The single-stranded genomic RNA of Taura syndrome virus (TSV) is 10205 nucleotides in length, excluding the 3′ poly(A) tail, and contains two large open reading frames (ORFs) that are separated by an intergenic region of 207 nucleotides. The ORFs are flanked by a 377 nucleotide 5′ untranslated region (UTR) and a 226 nucleotide 3′ UTR followed by a poly(A) tail. The predicted amino acid sequence of ORF1 revealed sequence motifs characteristic of a helicase, a protease and an RNA-dependent RNA polymerase, similar to the non-structural proteins of several plant and animal RNA viruses. In addition, a short amino acid sequence located in the N-terminal region of ORF1 presented a significant similarity with a baculovirus IAP repeat (BIR) domain of inhibitor of apoptosis proteins from double-stranded DNA viruses and from animals. The presence of this BIR-like sequence is the first reported in a single-stranded RNA virus, but its function is unknown. The N-terminal amino acid sequence of three TSV capsid proteins (55, 40 and 24 kDa) were mapped in ORF2, which is not in the same reading frame as ORF1 and possesses an AUG codon upstream of the structural genes. However, the intergenic region shows nucleotide sequence similarity with those of the genusCricket paralysis-like viruses, suggesting a similar non-AUG-mediated translation mechanism. The structure of the TSV genome [5′ UTR–non-structural proteins–intergenic UTR–structural proteins–3′ UTR–poly(A) tail] is similar to those of small insect-infecting RNA viruses, which were recently regrouped into a new virus genus,Cricket paralysis-like viruses.
Walleye dermal sarcoma virus reverse transcriptase is temperature sensitive
Authors: Fodor Sharon K. , Vogt Volker M. 
Published: August 2015

Walleye dermal sarcoma virus (WDSV) is a piscine retrovirus that replicates naturally in fish at temperatures near 4 °C. The reverse transcriptase (RT) protein from virus particles isolated from walleye tumours was purified and biochemically characterized. Like the RT of the distantly related murine leukaemia virus, WDSV RT sediments as a monomer in the absence of template. It exhibits aKmof 22 μM for TTP in an assay with poly(rA) as a template and oligo(dT) as a primer. The enzyme is rapidly inactivated at temperatures greater than 15 °C. The ratio of RT activity at 15 °C to that at 4 °C is similar for WDSV and recombinant human immunodeficiency virus type 1, suggesting that, at least with this template, the fish enzyme is not specially adapted to function more efficiently in the cold.
Infection with enterovirus 71 or expression of its 2A protease induces apoptotic cell death
Authors: Kuo Rei-Lin , Kung Szu-Hao , Hsu Yueh-Ying , Liu Wu-Tse 
Published: August 2015

Enterovirus 71 (EV71) is the causative agent of human diseases with distinct severity, from mild hand-foot-and-mouth disease to severe neurological syndromes, such as encephalitis and meningitis. Infection of several different cell lines with EV71 causes extensive cytopathic effect, leading to destruction of the entire monolayer and the death of infected cells. In this study, cell death processes during EV71 infection and the underlying mechanisms of them were investigated. The hallmarks of apoptosis, nuclear condensation and fragmentation, were observed 24 h after infection. Apoptosis in infected cells was also confirmed by detectable cleavage of cellular DNA and degradation of poly(ADP-ribose) polymerase. Transient expression of EV71 2A protease (2Apro) alone resulted in the induction of apoptotic change. Infection of EV71 or expression of EV71 2Aproleads to cleavage of the eukaryotic initiation factor 4GI, a key factor for host protein synthesis. This study added one more example to the growing list of human viruses that induce apoptosis by a virus-encoded protein.
Lack of involvement of haemocytes in the establishment and spread of infection in Spodoptera frugiperda larvae infected with the baculovirus Autographa californica M nucleopolyhedrovirus by intrahaemocoelic injection
Authors: Clarke Thomas E. , Clem Rollie J. 
Published: August 2015

It is thought that insect haemocytes, or blood cells, play an important role in baculovirus pathogenesis by amplifying and helping to spread the infection within the insect. Here, infection is described of the lepidopteran noctuid species Spodoptera frugiperda with the baculovirus Autographa californica M nucleopolyhedrovirus (AcMNPV). Late instar S. frugiperda larvae were infected by intrahaemocoelic injection using a recombinant of AcMNPV expressing the enhanced green fluorescent protein gene to visualize infected cells. Approximately 1000-fold higher doses of injected virus were required to initiate infection in S. frugiperda larvae than in another permissive noctuid species, Trichoplusia ni. Infected S. frugiperda larvae survived twice as long as T. ni larvae and exhibited a slower build-up of virus in the haemolymph. In S. frugiperda, infection of fat body and epithelium was observed prior to significant infection of haemocytes, even though the virus was delivered by intrahaemocoelic injection. Expression of eGFP was first detected 12–18 h post-injection within the fat body and, by 24 h, infection had spread to the tracheal and body wall epithelium. In contrast, only 5% of haemocytes were infected at 24 h and the proportion of infected haemocytes increased slowly to only around 50% at 5 days post-infection, when most larval death occurred. Thus, in S. frugiperda, haemocytes do not appear to have a primary role in AcMNPV pathogenesis. This relative lack of infection of haemocytes may in part explain why S. frugiperda larvae are more resistant to AcMNPV infection than T. ni larvae.
Identification of structural determinants of the first transmembrane domain of the small envelope protein of duck hepatitis B virus essential for particle morphogenesis
Authors: Grgacic Elizabeth V. L. 
Published: August 2015

The envelope of duck hepatitis B virus (DHBV) consists of the small (S) and large (L) envelope proteins, which share a common C-terminal multispanning transmembrane region but differ by the long N-terminal pre-S domain of L, which is essential for interactions with both the receptor and nucleocapsid. To achieve these dual functions, L acquires mixed topologies through S-dependent post-translational translocation of its pre-S domain. This study has examined the role of S in this unusual mechanism of translocation by analysis of the α-helical transmembrane domains and their potential to engage in lateral interactions for envelope assembly. Through mutagenesis in constructs expressing the S and L envelope proteins independently, transmembrane domain 1 was identified as an essential structural determinant in S. Two polar residues in this helix were identified as contributing to L protein translocation through the assembly of S into particles, implying that the topological switch of L is part of the assembly and maturation process. The same domain in L was shown to be dispensable for L translocation and assembly, suggesting that transmembrane domain 1 of L and S have different functional roles and structural arrangements on the assembled particle. The conservation in all hepadnavirus envelope proteins of two polar residues at positions 24 and 27 of transmembrane domain 1, the former positively charged, points to this being a common determinant in particle morphogenesis for all hepadnaviruses.
Experimental transfection of Macaca sylvanus with cloned human hepatitis B virus
Authors: Gheit Tarik , Sekkat Souad , Cova Lucyna , Chevallier Michèle , Petit Marie Anne , Hantz Olivier , Lesénéchal Mylène , Benslimane Abdallah , Trépo Christian , Chemin Isabelle 
Published: August 2015

Due to the absence of easily accessible animal models for the study of hepatitis B virus (HBV), the possibility of using Macaca sylvanus, a monkey originating from Morocco, North Africa, was investigated. Three monkeys were intrahepatically inoculated with a replication-competent head-to-tail HBV DNA plasmid dimer construct. The HBV surface antigen and HBV DNA were detected prior to alanine aminotransferase elevation in the serum of two of three HBV-inoculated monkeys at day 2 post-transfection and persisted for several weeks. This indicates that transfected animals developed markers of HBV infection. In addition, electron microscopy of the serum 3 weeks post-transfection showed the presence of virus particles whose shape and size were similar to complete 42 nm HBV Dane particles. Histological examination of liver tissues also revealed pathological changes not observed in uninfected controls, which strongly suggested acute hepatitis. HBV DNA was also detected by PCR in these monkey livers. Taken together, these results indicate that HBV can successfully replicate in this model and that M. sylvanus could be a potentially useful new primate model for the study of HBV replication.
Nucleotide sequence shows that Bean leafroll virus has a Luteovirus-like genome organization
Authors: Domier Leslie L. , McCoppin Nancy K. , Larsen Richard C. , D’Arcy Cleora J. 
Published: August 2015

The complete nucleotide sequence of the Bean leafroll virus (BLRV) genomic RNA and the termini of its smallest subgenomic RNAs were determined to better understand its mechanisms of gene expression and replication and its phylogenetic position within the Luteoviridae. The number and placement of open reading frames (ORFs) within the BLRV genome was Luteovirus-like. The nucleotide and predicted amino acid sequences of BLRV were most similar to those of Soybean dwarf virus (SbDV). Phylogenetic analyses employing the neighbour-joining method and sister-scanning analysis indicated that the BLRV nonstructural proteins were closely related to those of Barley yellow dwarf virus-PAV (BYDV-PAV), a Luteovirus. The region surrounding the frameshift at the junction between ORFs 1 and 2 also contained sequences very similar to those of BYDV-PAV and a Dianthovirus, Red clover necrotic mosaic virus. Similar analyses showed that the structural proteins were most similar to those of the Polerovirus genus. The 3′-noncoding regions downstream of ORF5 contained sequences similar to translational control elements identified in the BYDV-PAV genome. These data suggest that BLRV, like SbDV, is derived either through selection from a common ancestor with BYDV-PAV or that BLRV is the product of two recombination events between luteovirus-like and polerovirus-like ancestors where the 5′ 2900 nt and 3′ 700 nt of the BLRV genome are from a Luteovirus and the intervening sequences are derived from a Polerovirus.
Respiratory syncytial virus assembly occurs in GM1-rich regions of the host-cell membrane and alters the cellular distribution of tyrosine phosphorylated caveolin-1
Authors: Brown Gaie , Rixon Helen W. McL. , Sugrue Richard J. 
Published: August 2015

We have previously shown that respiratory syncytial virus (RSV) assembly occurs within regions of the host-cell surface membrane that are enriched in the protein caveolin-1 (cav-1). In this report, we have employed immunofluorescence microscopy to further examine the RSV assembly process. Our results show that RSV matures at regions of the cell surface that, in addition to cav-1, are enriched in the lipid-raft ganglioside GM1. Furthermore, a comparison of mock-infected and RSV-infected cells by confocal microscopy revealed a significant change in the cellular distribution of phosphocaveolin-1 (pcav-1). In mock-infected cells, pcav-1 was located at regions of the cell that interact with the extracellular matrix, termed focal adhesions (FA). In contrast, RSV-infected cells showed both a decrease in the levels of pcav-1 associated with FA and the appearance of pcav-1-containing cytoplasmic vesicles, the latter being absent in mock-infected cells. These cytoplasmic vesicles were clearly visible between 9 and 18 h post-infection and coincided with the formation of RSV filaments, although we did not observe a direct association of pcav-1 with mature virus. In addition, we noted a strong colocalization between pcav-1 and growth hormone receptor binding protein-7 (Grb7), within these cytoplasmic vesicles, which was not observed in mock-infected cells. Collectively, these findings show that the RSV assembly process occurs within specialized lipid-raft structures on the host-cell plasma membrane, induces the cellular redistribution of pcav-1 and results in the formation of cytoplasmic vesicles that contain both pcav-1 and Grb7.