Journal of General Virology最新文献

γδ T cells are a highly abundant lymphocyte subset in chickens and play key roles in early immune responses to infection. It has been recently shown that γδ T cells restrict Marek's disease virus (MDV) pathogenesis; however, it remained elusive if they play a role in vaccine protection. In this study, we vaccinated γδ T-cell-knockout chickens with the commercial turkey herpesvirus (HVT) vaccine and challenged them with very virulent MDV. The disease incidence was significantly increased in vaccinated chickens in the absence of γδ T cells. This increase was comparable to a previous study in unvaccinated γδ T-cell-knockout chickens, suggesting that γδ T cells only play a minor role in vaccine protection. Furthermore, the viral load in the spleen was significantly increased in the absence of γδ T cells. Interestingly, viral load in the skin and in dust shed by the animals was drastically increased, suggesting that the absence of γδ T cells affects MDV shedding. In addition, we quantified various immune cell subsets to determine if these could be responsible for the observed phenotypes. Together, our data indicate that γδ T cells only play a minor role in HVT-mediated protection, but their absence drastically affects shedding of this deadly pathogen in vaccinated animals.

Previous research has demonstrated that influenza A virus (IAV) infection activates activating protein-1 (AP-1) transcription factors as part of the antiviral response. In this study, we identified cFos as the most upregulated AP-1 transcription factor during IAV infection in A549 human lung cells. Surprisingly, the knockdown of cFos resulted in impaired IAV replication. Fluorescence microscopy and functional analyses indicated that cFos is implicated in IAV infection through its nuclear function, rather than its cytoplasmic role as an activator of lipid synthesis. The investigation into the role of cFos in IAV infection revealed increased apoptosis and elevated interferon-β mRNA levels in cFos-knockdown A549 cells during IAV infection. This suggests that cFos may enhance cell survival and reduce interferon-β expression during infection, thereby facilitating IAV proliferation. Furthermore, the levels of viral NA mRNA and the expression of late viral proteins NA and M2 decreased upon cFos-knockdown. Overall, this study identifies cFos as a proviral factor for IAV, through the modulation of innate immunity and apoptosis during infection, and potentially by supporting the viral transcription.

Atkinsonella hypoxylon virus (AhV) is a fungi-infecting betapartitivirus and the typical member of the Partitiviridae, a family of persistent viruses that infect a broad range of organisms. Partitiviruses have been largely overlooked following their designation as cryptic viruses. However, evidence is accumulating that they play an important role in the ecology of their hosts. Since the capsid proteins of partitiviruses have been implicated in virus-host interactions, exploring their structural biology may give clues into the evolution, horizontal transmission and host adaptation of partitiviruses. The capsid of AhV shares the same organization of other partitiviruses with 60 dimeric capsid protein protomers arranged with T=1 icosahedral symmetry. The structure, determined by cryo-electron microscopy to 2.4 Å, shows that AhV has a unique iteration on the protrusion domain with an extensive network of hydrophobic interactions among equivalent interdigitating loops at the dimerization interface. AhV also shares a conserved helical core in the shell domain, which we extend to all genera of the recognized partitiviruses using protein structure prediction. The helical core appears to be a conserved element of the picobirnavirus lineage of capsid protein folds and provides a template onto which various elaborations of the protrusion domain have evolved. The involvement of the protrusion in virus-host interactions has previously been proposed, and our findings provide evidence of a structural device enabling capsid protein diversification during the evolution of the Partitiviridae.

The development of an effective prophylactic hepatitis C virus (HCV) vaccine is a priority to achieve global elimination of the virus. Accurate assessment of the neutralizing breadth of antibodies induced by vaccines and a clear understanding of the antigenic differences between viral variants included in vaccines are both critical for vaccine development. Prior studies have indicated that HCV genotypes (gts) do not dictate the sensitivity of HCV envelope glycoprotein (E1E2) variants to neutralizing antibodies. However, most of these prior studies under-sampled variants from gts 2-6. Here, we selected a genetically diverse and representative panel of gt 2-6 E1E2 variants, used them to generate HCV pseudoparticles (HCVpp), and measured neutralization of these HCVpp by neutralizing antibodies and HCV-immune plasma from persons infected with gt 1-6 viruses. We found that neutralization results obtained with this gt 2-6 panel were remarkably similar to results obtained with a previously described, antigenically diverse, gt 1-predominant reference panel of 15 HCVpp. These data confirm that, even considering genetically diverse HCV variants across gt 1-6, E1E2 antigenicity is not dictated by gt, and that the previously published panel of 15 HCVpp represents neutralization of all HCV gts with reasonable accuracy.

Ovine herpesvirus 1 (OvHV-1) was first identified over 50 years ago in sheep with ovine pulmonary adenocarcinoma (OPA). An aetiological role in OPA was later ruled out and OvHV-1 was found to be a common infection in sheep in several countries. Here, we report the sequence and annotation of the complete OvHV-1 genome. The virus has a similar genomic architecture to members of the Macavirus genus of the subfamily Gammaherpesvirinae and is most closely related to bovine gammaherpesvirus 6 (BoGHV6). The OvHV-1 genome comprises a 144,637 bp unique region predicted to encode at least 74 proteins bounded by multiple copies of a 699 bp GC-rich repetitive terminal repeat. Predicted genes include 61 ORFs conserved among all gammaherpesviruses, and 12 genes present only in macavirus genomes, including a homologue of ovine IL-10, previously reported only in ovine gammaherpesvirus 2, and an ornithine decarboxylase, previously described only in BoGHV6. A further gene appears unique to OvHV-1 among macaviruses, encoding a viral-FLIP (FLICE-like inhibitory protein), similar to those found in some other gammaherpesviruses. Notably, several macavirus genes previously predicted in BoGHV6 are defective in OvHV-1. The availability of the genome sequence of OvHV-1 will facilitate studies on its relationship to other macaviruses and its role, if any, in disease.

Senecavirus A (SVA) is a picornavirus that was first isolated in the USA in 2002; however, there is evidence that the virus was circulating in swine herds since 1988. Despite frequent reports of vesicular disease outbreaks caused by SVA infection in swine in Brazil since 2014, there is limited data on the genetic diversity and evolution of the virus in the country. SVA was isolated from swine exhibiting vesicular lesions, with samples originating from farms or slaughterhouses across 57 municipalities in 8 Brazilian states between 2018 and 2022. We obtained 501 SVA genomes through Sanger and Oxford Nanopore sequencing. Phylogenetic analysis revealed that Brazilian SVA sequences are genetically distinct from sequences from other countries, including China, USA and Canada, and form a monophyletic cluster, indicating a common ancestor for the viruses currently circulating in Brazil. Furthermore, there are two main clusters with sequences from the Midwest and Southern regions, suggesting that SVA is evolving independently in the swine population of the country. Pairwise sequence comparisons allowed us to identify seven unique mutations with high frequency in the Brazilian SVA sequences. Notably, mutations were identified in specific regions of the capsid proteins that interact with the host cell receptor (ANTRX1) and in surface-exposed residues, suggesting potential evolutionary changes due to receptor interaction or immune pressure. Recombination analysis provided evidence of at least five recombination events among the Brazilian strains. These findings offer new insights into the evolution of SVA circulating in Brazil and into the global epidemiology/evolutionary dynamics of the virus.

The nucleolus is a multifunctional hub and a common target of viral proteins, yet its role in infections by cytoplasmically replicating RNA viruses remains poorly defined. In rabies virus (RABV), the phosphoprotein (P-protein) isoform P3 localizes to nucleoli and inhibits rRNA biogenesis, whereas P1 lacks nucleolar targeting, even when forced into the nucleus. Here, we show that nucleolar targeting is an isoform- and phylogroup-specific property of lyssavirus P-proteins. Isoforms P3-P5 accumulate in nucleoli, whereas P1 and P2 are excluded. Comparative analyses revealed that P3 nucleolar targeting is conserved in phylogroup I but absent in phylogroup II lyssaviruses. Co-immunoprecipitation assays identified conserved interactions with nucleolin and nucleophosmin (NPM1) but divergent binding to Treacle and nucleolar and coiled-body phosphoprotein 1 (NOLC1). These findings define nucleolar targeting as a gain-of-function of truncated P isoforms, demonstrate its conservation across phylogroup I lyssaviruses and suggest broader engagement with membraneless compartments, highlighting potential therapeutic vulnerabilities.

Cytomegalovirus (CMV) is a beta herpesvirus that persists quiescently in healthy individuals but causes severe disease in immunocompromised patients and congenitally infected newborns. Side effects posed by the currently available antivirals necessitate the development of new antivirals with improved safety profiles. This study aims to optimize the potency of an anti-CMV peptide (P10) mimicking conserved region 2 of tegument pp150, fused with an elastin-like polypeptide (ELP). Our previous study has demonstrated that ELP-P10 inhibits murine cytomegalovirus (MCMV) growth in vitro and in vivo with enhanced pharmacokinetic properties relative to the free peptide. To enhance the potency of ELP-P10 at a lower concentration, this study utilizes a cell-penetrating peptide, SynB1, to facilitate the delivery of ELP-P10 into the cells. SynB1 was added to the N terminus of ELP-P10 to generate SynB1-ELP-P10. Antiviral efficacy and cytotoxic effects of ELP-P10 and SynB1-ELP-P10 were studied in cell culture. Pharmacokinetics, biodistribution and antiviral efficacy were studied in a mouse model of CMV infection. While ELP-P10 maintained significant antiviral activity against human cytomegalovirus (HCMV) in cell culture at a higher concentration, SynB1-ELP-P10 shows potency against HCMV and MCMV at a threefold lower concentration compared to ELP-P10. SynB1-ELP-P10 had similar bioavailability after subcutaneous administration as ELP-P10, and SynB1 conjugation to ELP-P10 significantly enhanced its accumulation in the kidneys. Moreover, in an in vivo model of CMV infection, ELP-P10 and SynB1-ELP-P10 treatment led to a significant reduction in the viral titre compared to controls. In conclusion, the strategic modification of ELP-P10 with SynB1 potentiated CMV inhibition, allowing for the use of lower therapeutic doses and mitigating potential side effects.

Human torque teno viruses are emerging infectious agents distributed globally and have increasingly been reported to be associated with human diseases. To identify potential anelloviral sequences in available metagenomic data, an in silico screening was performed mainly employing the ORF1, ORF2 and ORF3 nucleotide/protein queries of known human anelloviruses and identified 217 complete ORF1 regions. Pairwise nucleotide-identity analysis with a 69% cut-off - consistent with ICTV species demarcation - revealed 117 novel species across the 3 major human-infecting genera: 15 in Alphatorquevirus, 51 in Betatorquevirus and 51 in Gammatorquevirus. In nearly all cases, these species assignments correspond precisely to monophyletic clusters in maximum-likelihood phylogenies of ORF1 amino acid sequences. Using AlphaFold3-guided modelling together with representative ORF1 alignments, we delineated capsid motifs - the conserved jelly-roll (JR) β-sandwich core (β-strands B-I) and the outward projection domains P1/P2 - and quantified motif lengths across genera, revealing tightly constrained JR lengths with genus-specific but overlapping variation in P1/P2. A few exceptions - where pairwise-based groupings split or merge slightly differently - highlight ongoing challenges in delineating rapidly evolving viruses. Notably, the two deeply branching isolates retain the canonical JR core while exhibiting a TTMDV-like short P2, indicating preservation of key capsid architecture in the newly proposed genus. This work nearly doubles the known species richness of human anelloviruses and introduces a novel genus, underscoring the vast, hidden diversity of the gut virome and its potential impact on human health. By coupling taxonomy with structure-informed ORF1 motif analysis, our study provides biological context for these lineages and a framework for future functional and immunological investigations.

A new curvulavirid was isolated from a Japanese strain of the filamentous ascomycete Cryphonectria nitschkei and thoroughly characterized. The virus termed Cryphonectria nitschkei curvulavirus 1 (CnCvV1) has a bi-segmented dsRNA genome. CnCvV1 dsRNA1 encodes an RNA-dependent RNA polymerase (592 amino acids), while dsRNA2 possesses two ORFs, one that encodes a protein associated with the genomic dsRNA and the other that encodes a hypothetical protein of unknown function. CnCvV1 could be experimentally introduced into another virus-free strain of C. nitschkei and two strains of different fungal species within the genus Cryphonectria (Cryphonectria parasitica and Cryphonectria carpinicola). Based on phenotypic comparison, the virus caused asymptomatic infection in the three newly established fungal strains. However, there was a reduced colony growth rate and increased CnCvV1 accumulation in an RNA silencing-deficient mutant (Δdcl2), relative to the wt strain EP155 of a model virus host fungus (C. parasitica). These findings suggest that CnCvV1 is targeted by RNA silencing in C. parasitica. This study provides a foundation for further exploration of curvulavirids that have been biologically understudied.