2014, 29(2): 71 doi: 10.1007/s12250-014-3451-9
2014, 29(2): 74 doi: 10.1007/s12250-014-3438-6
Flaviviruses are positive-sense RNA viruses, and many are important human pathogens. Nonstructural protein 2B and 3 of the flaviviruses (NS2BNS3) form an endoplasmic reticulum (ER) membraneassociated hetero-dimeric complex through the NS2B transmembrane region. The NS2BNS3 complex is multifunctional. The N-terminal region of NS3, and its cofactor NS2B fold into a protease that is responsible for viral polyprotein processing, and the C-terminal domain of NS3 possesses NTPase/RNA helicase activities and is involved in viral RNA replication and virus particle formation. In addition, NS2BNS3 complex has also been shown to modulate viral pathogenesis and the host immune response. Because of the essential functions that the NS2BNS3 complex plays in the flavivirus life cycle, it is an attractive target for antiviral development. This review focuses on the recent biochemical and structural advances of NS2BNS3 and provides a brief update on the current status of drug development targeting this viral protein complex.
The VP2 protein of grass carp reovirus (GCRV) expressed in a baculovirus exhibits RNA polymerase activity
2014, 29(2): 86 doi: 10.1007/s12250-014-3366-5
The double-shelled grass carp reovirus (GCRV) is capable of endogenous RNA transcription and processing. Genome sequence analysis has revealed that the protein VP2, encoded by gene segment 2 (S2), is the putative RNA-dependent RNA polymerase (RdRp). In previous work, we have ex-pressed the functional region of VP2 that is associated with RNA polymerase activity (denoted as rVP2390-900) in E. coli and have prepared a polyclonal antibody against VP2. To characterize the GCRV RNA polymerase, a recombinant full-length VP2 (rVP2) was first constructed and expressed in a baculovirus system, as a fusion protein with an attached His-tag. Immunofluorescence (IF) assays, together with immunoblot (IB) analyses from both expressed cell extracts and purified Histagged rVP2, showed that rVP2 was successfully expressed in Sf9 cells. Further characterization of the replicase activity showed that purified rVP2 and GCRV particles exhibited poly(C)-dependent poly(G) polymerase activity. The RNA enzymatic activity required the divalent cation Mg2+, and was optimal at 28 ℃. The results provide a foundation for further studies on the RNA polymerases of aquareoviruses during viral transcription and replication.
2014, 29(2): 94 doi: 10.1007/s12250-014-3382-5
The biological features of most foamy viruses (FVs) are poorly understood, including bovine foamy virus (BFV). BFV strain 3026 (BFV3026) was isolated from the peripheral blood mononuclear cells of an infected cow in Zhangjiakou, China. A full-length genomic clone of BFV3026 was obtained from BFV3026-infected cells, and it exhibited more than 99% amino acid (AA) homology to another BFV strain isolated in the USA. Upon transfection into fetal canine thymus cells, the full-length BFV3026 clone produced viral structural and auxiliary proteins, typical cytopathic effects, and virus particles. These results demonstrate that the full-length BFV3026 clone is fully infectious and can be used in further BFV3026 research.
Single amino acid substitution of VP1 N17D or VP2 H145Y confers acid-resistant phenotype of type Asia1 foot-and-mouth disease virus
2014, 29(2): 103 doi: 10.1007/s12250-014-3426-x
Infection by foot-and-mouth disease virus (FMDV) is triggered by the acidic pH in endosomes after virus uptake by receptor-mediated endocytosis. However, dissociation of the FMDV 146S particle in mildly acidic conditions renders inactivated foot-and-mouth disease (FMD) vaccines much less effective. Type Asia1 FMDV mutants with increased resistance to acid inactivation were selected to study the molecular basis of viral resistance to acid-induced disassembly and improve the acid stability of FMDV. Sequencing of capsid-coding regions revealed four amino acid replacements (VP1 N17D, VP2 H145Y, VP2 G192D, and VP3 K153E) in the viral population of the acid-selected 10th passage. We performed single or combined mutagenesis using a reverse genetic system, and our results provide direct experimental evidence that VP2 H145Y or VP1 N17D substitution confers an acid-resistant phenotype to type Asia1 FMDV.
2014, 29(2): 119 doi: 10.1007/s12250-014-3443-9
2014, 29(2): 123 doi: 10.1007/s12250-014-3384-3
The limited number of available nucleotide and protein sequence data from the recent H7N9 cases in China impeded investigation and characterization of the outbreak
2014, 29(2): 126 doi: 10.1007/s12250-014-3394-1
Influence of HLA gene polymorphisms on susceptibility and outcome post infection with the SARS-CoV virus
2014, 29(2): 128 doi: 10.1007/s12250-014-3398-x
A SYBR-Green I quantitative Real-time Reverse Transcription- PCR assay for rabies viruses with different virulence
2014, 29(2): 131 doi: 10.1007/s12250-014-3378-1
3’-UTR sequence of Macrobrachium rosenbergii extra small virus (XSV) is important for viral RNA packaging
2014, 29(2): 133 doi: 10.1007/s12250-014-3418-x
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