The Journal of general virology
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The emerging pathogen severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused social and economic disruption worldwide, infecting over 9.0 million people and killing over 469 000 by 24 June 2020. Unfortunately, no vaccine or antiviral drug that completely eliminates the transmissible disease coronavirus disease 2019 (COVID-19) has been developed to date. Given that coronavirus nonstructural protein 1 (nsp1) is a good target for attenuated vaccines, it is of great significance to explore the detailed characteristics of SARS-CoV-2 nsp1. ⋯ Specifically, bioinformatics and biochemical experiments showed that by interacting with 40S ribosomal subunit, the lysine located at amino acid 164 (K164) was the key residue that enabled SARS-CoV-2 nsp1 to suppress host gene expression. Furthermore, as an inhibitor of host-protein expression, SARS-CoV-2 nsp1 contributed to cell-cycle arrest in G0/G1 phase, which might provide a favourable environment for virus production. Taken together, this research uncovered the detailed mechanism by which SARS-CoV-2 nsp1 K164 inhibited host gene expression, laying the foundation for the development of attenuated vaccines based on nsp1 modification.
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Neuraminidase inhibitors (NAIs) are the gold standard treatment for influenza A virus (IAV). Oseltamivir is mostly used, followed by zanamivir (ZA). NAIs are not readily degraded in conventional wastewater treatment plants and can be detected in aquatic environments. ⋯ Two neuraminidase substitutions emerged, H274N (ZA IC50 increased 5.5-fold) and E119G (ZA IC50 increased 110-fold) at 10 and 100 µg l-1 of ZA, respectively. Reversion towards wild-type was observed for both substitutions in experiments with removed drug pressure, indicating reduced fitness of both resistant viruses. These results corroborate previous findings that the development of resistance to ZA in the environment seems less likely to occur than the development of resistance to oseltamivir, adding information that is useful in planning for prudent drug use and pandemic preparedness.
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SARS-CoV-2 is a novel coronavirus that is the causative agent of coronavirus infectious disease 2019 (COVID-19). As of 17 April 2020, it has infected 2 114 269 people, resulting in 145 144 deaths. The timing, magnitude and longevity of humoral immunity is not yet understood for SARS-CoV-2. ⋯ Two other coronaviruses, SARS and MERS, have crossed from animal sources into humans but have not become endemic. Here we review what is known about the human humoral immune response to epidemic SARS CoV and MERS CoV and to the seasonal, endemic coronaviruses. Then we summarize recent, mostly non-peer reviewed, studies into SARS-CoV-2 serology and reinfection in humans and non-human primates and summarize current pressing research needs.
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Zika virus (ZIKV, genus Flavivirus) has emerged as a major mosquito-transmitted human pathogen, with recent outbreaks associated with an increased incidence of neurological complications, particularly microcephaly and the Guillain-Barré syndrome. Because the virus has only very recently emerged as an important pathogen, research is being hampered by a lack of reliable molecular tools. Here we report an infectious cDNA (icDNA) clone for ZIKV isolate BeH819015 from Brazil, which was selected as representative of South American ZIKV isolated at early stages of the outbreak. icDNA clones were assembled from synthetic DNA fragments corresponding to the consensus sequence of the BeH819015 isolate. ⋯ A ZIKV subgenomic replicon, lacking a prM- and E glycoprotein encoding region and expressing a Gaussia luciferase marker, was constructed and shown to replicate both in mammalian and insect cells. In the presence of the Semliki Forest virus replicon, expressing ZIKV structural proteins, the ZIKV replicon was packaged into virus-replicon particles. Efficient reverse genetic systems, genetically stable marker viruses and packaged replicons offer significant improvements for biological studies of ZIKV infection and disease, as well as for the development of antiviral approaches.
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During 2013, a novel equine-like G3P[8] rotavirus emerged as the dominant strain in Australian children with severe rotavirus gastroenteritis. Full genome analysis demonstrated that the strain was an inter-genogroup reassortant, containing an equine-like G3 VP7, a P[8] VP4 and a genogroup 2 backbone I2-R2-C2-M2-A2-N2-T2-E2-H2. The genome constellation of the equine-like G3P[8] was distinct to Australian and global G3P[8] strains. ⋯ The Australian equine-like G3P[8] strain displayed a distinct VP7 antigenic profile when compared with the previously circulating Australian G3P[8] strains. Identification of similar genes in strains from several geographical regions suggested the equine-like G3P[8] strain was derived by multiple reassortment events between globally co-circulating strains from both human and animal sources. This study reinforces the dynamic nature of rotavirus strains and illustrates the potential for novel human/animal reassortant strains to emerge within the human population.