Henrymouridsen1636

o be organized in a state of flux, which could be important for co-factor/receptor binding functions. Blocking these capsid-binding events with Nanobodies directly inhibited essential capsid functions. Moreover, a number of MNV-specific Nanobody binding epitopes were comparable to human norovirus-specific Nanobody inhibitors. Therefore, this additional structural and inhibition information could be further exploited in the development of human norovirus antivirals. Copyright © 2020 American Society for Microbiology.Highly pathogenic avian influenza (HPAI) viruses are enzootic in wild birds and poultry and continue to cause human infections with high mortality. To date, more than 850 confirmed human cases of H5N1 virus infection have been reported, of which ∼60% were fatal. Global concern persists that these or similar avian influenza viruses will evolve into viruses that can transmit efficiently between humans, causing a severe influenza pandemic. It was shown previously that a change in receptor specificity is a hallmark for adaptation to humans and evolution towards a transmittable virus.Substantial genetic diversity was detected within the receptor binding site of hemagglutinin of HPAI A/H5N1 viruses, evolved during human infection, as detected by next generation sequencing. Here we investigated the functional impact of substitutions that were detected during these human infections. Upon rescue of 21 mutant viruses, most substitutions in the RBS resulted in viable virus, but virus replication, entry and stability werly in a diverse set of assays, including virus replication, stability and receptor specificity. None of the tested substitutions resulted in a clear step towards a human adapted virus capable of aerosol transmission. It is notable that acquiring human-type receptor specificity needs multiple amino acid mutations, and that variability at key position 226 is not tolerated, reducing the risk of them being acquired naturally. Copyright © 2020 American Society for Microbiology.Low pathogenic avian influenza viruses (LPAIVs) are genetically highly variable and have diversified into multiple evolutionary lineages that are primarily associated with wild bird reservoirs. Antigenic variation has been described for mammalian influenza viruses and for highly pathogenic avian influenza viruses that circulate in poultry, but much less is known about antigenic variation of LPAIVs. In this study, we focussed on H13 and H16 LPAIVs that circulate globally in gulls. We investigated the evolutionary history and intercontinental gene flow based on the hemagglutinin (HA) gene and used representative viruses from genetically distinct lineages to determine their antigenic properties by hemagglutination inhibition assays. For H13 at least three distinct genetic clades were evident, while for H16 at least two distinct genetic clades were evident. Twenty and ten events of intercontinental gene flow were identified for H13 and for H16 viruses, respectively. At least two antigenic variants of H13 and at ltercontinental gene flow, and the antigenic variation among H13 and H16 LPAIVs. The circulation of the subtypes H13 and H16 seems to be maintained by a narrower host range, in particular gulls, than for the majority of LPAIV subtypes and may therefore serve as a model for evolution and epidemiology of H1-H12 LPAIVs in wild birds. The findings suggest that H13 and H16 LPAIVs circulate independently of each other and emphasize the need to investigate within clade antigenic variation of LPAIVs in wild birds. Copyright © 2020 Verhagen et al.Non-segmented negative-strand (NNS) RNA viruses possess a ribonucleoprotein template in which the genomic RNA is sequestered within a homopolymer of nucleocapsid protein (N). The viral RNA dependent RNA polymerase (RdRP) resides within an approximately 250 kDa large protein (L), along with unconventional mRNA capping enzymes - a GDPpolyribonucleotidyltransferase (PRNT) and a dual specificity mRNA cap methylase (MT). To gain access to the N-RNA template and orchestrate the LRdRP, LPRNT and LMT, an oligomeric phosphoprotein (P) is required. Vesicular stomatitis virus (VSV) P is dimeric with an oligomerization domain (OD) separating two largely disordered regions followed by a globular C-terminal domain that binds template. P is also responsible for bringing new N protomers onto the nascent RNA during genome replication. We show VSV P lacking the OD (PΔOD) is monomeric but is indistinguishable from wild type P in supporting mRNA transcription in vitro. Recombinant virus VSV-PΔOD, exhibits a pronounced kinetic deV), we determined the importance of P oligomerization. We find that oligomerization of VSV P is not required for any step of viral mRNA synthesis but is required for efficient RNA replication. We present evidence that this likely occurs through the stage of loading soluble N onto the nascent RNA strand as it exits the polymerase during RNA replication. Interfering with the oligomerization of P may represent a general strategy to interfere with NNS RNA virus replication. Copyright © 2020 Bloyet et al.Rabies virus (RABV) causes a severe and fatal neurological disease, but morbidity is vaccine preventable and treatable prior to the onset of clinical symptoms. However, immunoglobulin (IgG)-based rabies post-exposure prophylaxis (PEP) is expensive, restricting access to life-saving treatment especially for patients in low-income countries where clinical need is greatest, and does not confer cross-protection against newly emerging phylogroup II lyssaviruses. Towards identifying a cost-effective replacement for the IgG component of rabies PEP, we developed and implemented a high-throughput screening protocol utilizing a single cycle RABV reporter strain. A large-scale screen and subsequent direct and orthogonal counterscreens identified a first-in-class direct-acting RABV inhibitor, GRP-60367, with a specificity index SI >100,000. Mechanistic characterization through time-of-addition studies, transient cell-to-cell fusion assays, and chimeric vesicular stomatitis virus (VSV) recombinants expressing the RABV gly to life saving medication. This study has established a robust protocol for high-throughput anti-RABV drug screens and identified a chemically well-behaved, first-in-class hit with nanomolar anti-RABV potency that blocks RABV G protein-mediated viral entry. Resistance mapping revealed a druggable site formed by the G protein fusion loops that has not previously emerged as a target for neutralizing antibodies. Discovery of this RABV entry inhibitor establishes a new molecular probe to advance further mechanistic and structural characterization or RABV G that may aid in the design of a next-generation clinical candidate against RABV. Copyright © 2020 American Society for Microbiology.The small messenger RNA (SmRNA) of the Andes orthohantavirus (ANDV), a rodent-borne member of the Hantaviridae family of viruses of the Bunyavirales order, encodes for a multifunctional nucleocapsid (N) protein and for a nonstructural (NSs) protein of unknown function. We have previously shown the expression of the ANDV-NSs, but only in infected cell cultures. In this study, we extend our early findings by confirming the expression of the ANDV-NSs protein in the lungs of experimentally infected golden Syrian hamsters. Next, we show, using a virus-free system, that the ANDV-NSs protein antagonizes the type I IFN induction pathway by suppressing signals downstream of MDA5 and RIG-I and upstream of TBK1. Consistent with this observation, the ANDV-NSs protein antagonized MAVS-induced IFNβ, NFκB, IRF3, and ISRE promoter activity. Results demonstrate that ANDV-NSs binds to MAVS in cells without disrupting the MAVS-TBK-1 interaction. However, in the presence of the ANDV-NSs ubiquitination of MAVS is reduced. In summon. Copyright © 2020 American Society for Microbiology.The Birnaviridae family, responsible for major economic losses to poultry and aquaculture, are non-enveloped viruses with a segmented double-stranded (ds)RNA genome that replicate in discrete cytoplasmic virus factories (VFs). Reassortment is common, however, the underlying mechanism remains unknown given that VFs may act as a barrier to genome mixing. In order to provide new information on VF trafficking during dsRNA virus co-infection, we rescued two recombinant infectious bursal disease viruses (IBDVs) of strain PBG98 containing either a split GFP11- or Tetracysteine (TC)- tag fused to the VP1 polymerase (PBG98-VP1-GFP11 and PBG98-VP1-TC). DF-1 cells transfected with GFP1-10 prior to PBG98-VP1-GFP11 infection, or stained with ReAsH following PBG98-VP1-TC infection, had green or red foci in the cytoplasm respectively that co-localised with VP3 and dsRNA, consistent with VFs. The average number of VFs decreased from a mean of 60 to 5 per cell between 10 and 24 hours post infection (hpi) (p less then 0.0001),ses to track the location and movement of IBDV VFs, in order to better understand the intracellular dynamics of VFs during a co-infection. Discrete VFs initially formed from each virus that subsequently coalesced from 10 hours pi. We hypothesise that VF coalescence is required for the reassortment of the Birnaviridae. This study provides new information that adds to our understanding of dsRNA virus VF trafficking. Wnt agonist 1 Wnt activator Copyright © 2020 Campbell et al.Nipah (NiV) and Hendra virus (HeV), members of the henipavirus genus in the Paramyxoviridae family, are recently emerged, highly lethal zoonotic pathogens. The NiV and HeV non-segmented, negative-sense RNA genomes encode for nine proteins, including the W protein. Expressed from the P gene through mRNA editing, W shares a common N-terminus with P and V, but has a unique C-terminus. Expressed alone, W modulates innate immune responses by several mechanisms and elimination of W from NiV alters the course of infection in experimentally-infected-ferrets. However, the specific host interactions that allow W to modulate innate immunity are incompletely understood. This study demonstrates that the NiV and HeV W proteins interact with all seven isoforms of the 14-3-3 family, regulatory molecules that preferentially bind phosphorylated target proteins to regulate a wide range of cellular functions. The interaction is dependent on the penultimate amino acid residue in the W sequence, a conserved, phosphorylated serine.on of 14-3-3 regulated host signaling pathways not previously associated with W, suggesting new avenues of research. The co-crystal structure of the NiV W14-3-3 complex, as only the second structure of a 14-3-3 mode III interactor, provides further insight into this less well understood 14-3-3 binding motif. Copyright © 2020 American Society for Microbiology.The human cytomegalovirus (HCMV) UL50 gene encodes a transmembrane protein, pUL50, which acts as a core component of the nuclear egress complex (NEC) for nucleocapsids. Recently, pUL50 has been shown to have NEC-independent activities; downregulation of IRE1 to repress the unfolded protein response and degradation of UBE1L to inhibit the protein ISG15 modification pathway. Here, we demonstrate that a 26-kDa N-terminal truncated isoform of pUL50 (UL50-p26) is expressed from an internal methionine at amino acid position 199, and regulates the activity of pUL50 to induce loss of valosin-containing protein (VCP/p97). UL50(M199V) mutant virus expressing pUL50(M199V) but not UL50-p26 showed delayed growth at low multiplicity of infection. There was also delayed accumulation of viral immediate-early (IE) 2 protein in the mutant virus, and this correlated with reduced expression of VCP/p97, which promotes IE2 expression. Infection with mutant virus did not significantly alter ISGylation levels. In transient expression assays, pUL50 induced VCP/p97 loss post-transcriptionally, and this was dependent on the presence of its transmembrane domain.