Journal of General Virology最新文献

The family Apasviridae includes dsDNA viruses associated with the marine archaeal lineage Poseidoniales. Members of this family have been identified using metagenomic analyses of brackish estuarine samples and are related to other 'magroviruses' infecting Poseidoniales archaea. The family belongs to the order Magrovirales and includes the genus Agnivirus and the species Agnivirus brisbanense. Viruses in the family possess a linear dsDNA genome of about 108 kbp and encode modules for DNA replication and virion morphogenesis, such as those relating to the formation of an icosahedral capsid and a helical tail, characteristic of members of the class Caudoviricetes. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Apasviridae, which is available at ictv.global/report/apasviridae.

Differentiating Creutzfeldt-Jakob disease (CJD) with the V180I mutation from other types of dementia is extremely difficult. Additionally, its differentiation is sometimes determined after performing neurosurgery, which is associated with a high risk of V180I prion contamination; however, the infectivity of the V180I prion has not been properly investigated. Especially in East Asia, this issue must be addressed to respond effectively to accidental contamination that leads to iatrogenic CJD. The results of our transmission experiments involving various humanized knock-in mice clearly indicate that the transmissibility of tissue from V180I genetic CJD cases is significantly limited.

Infectious bursal disease virus (IBDV) causes an endemic immunosuppressive disease in chickens. Prior exposure to IBDV influences the pathogenesis and shedding of chicken strains of influenza A virus (IAV), but its effect on waterfowl strains is poorly understood. To address this, we inoculated 14-day-old specific pathogen-free chickens with low pathogenicity avian influenza strain A/Mallard/Alberta/156/01 (H3N8) and compared the replication, shedding, pathogenesis, transmission and intra-host evolution between immunocompetent chickens and chickens that had IBDV-mediated immune dysregulation due to a prior infection with strain F52/70 at 2 days of age. The IAV replicated in the upper respiratory tract, and the virus was shed from the oropharyngeal cavity, but there was no shedding from the cloaca and no transmission to sentinel chickens. IAV replication in chickens was associated with amino acid substitutions in the polymerase complex and HA. Prior IBDV infection had no significant effect on IAV pathogenicity, replication or shedding and had a modest effect on IAV diversity, increasing the number of amino acid substitutions from an average of 2.50 substitutions per sample (sd±1.83) in the Mock/IAV group to 4.75 (sd±1.81) in the IBDV/IAV group (P<0.01). Taken together, our data suggest that IBDV is unlikely to play a major role in the spillover or spread of waterfowl IAV strains in chicken flocks, although it could expand IAV diversity. This information is useful for informing preventative measures for controlling IAV in poultry flocks.

Viral pathogens pose an emerging threat to the sustainability of insect mass-rearing systems, yet they remain understudied in key species like the black soldier fly (BSF; Hermetia illucens). Although multiple viral sequences have been reported in BSF, their role in disease has not been established until now. Here, we provide the first in vivo characterization of H. illucens solinvivirus (HiSvV), confirming its role as a viral entomopathogen of BSF. Metatranscriptomic analysis of a diseased colony revealed a high viral load attributable to HiSvV. We successfully isolated the virus and developed injection- and oral-based infection assays to investigate replication, tissue tropism, transmission and risk of mortality. HiSvV replicated in inoculated adults, induced premature mortality in flies and was transmitted both horizontally and vertically. Infected flies also mounted a broad antiviral response, which supported active pathogenesis, even if the small RNA pathways were not activated. These findings establish HiSvV as the first confirmed viral pathogen of BSF and underscore the urgent need for viral surveillance and experimental tools to safeguard industrial insect rearing.

Herpes simplex virus (HSV)-1 infection of cortical neurones is a leading cause of encephalitis. Whilst we have substantial knowledge about the molecular virology of HSV-1 lytic infection in cells of the periphery, like keratinocytes or fibroblasts, we know much less about infection of human neurones owing to the challenges of working with neuronal cell-based models. Here, we demonstrate the use of a human induced pluripotent stem cell-derived cortical neurone model (i3Neurones) for HSV-1 infection. i3Neurones are highly scalable and can be rapidly and efficiently differentiated into an isogenic population of cortical glutamatergic neurones. We show that i3Neurones support the full HSV-1 lytic replication cycle. We present an optimized protocol for the infection of i3Neurones with HSV-1 that allows their synchronous infection at near-100% efficiency and optimized fixation methods that preserve organelle and neurite structure for immunocytochemistry analysis. Our study highlights i3Neurones as a robust, scalable platform for microscopy and biochemical studies of HSV-1 and other neurotropic pathogens.

While rapid death is the usual outcome of high pathogenicity avian influenza virus (HPAIV) infection in gallinaceous poultry, HPAIV-infected ducks usually present milder clinical signs and shed virus for a prolonged time. The difference in disease severity has been linked to a more rapid type I IFN immune response and reduced proinflammatory cytokine expression in ducks compared to chickens. To investigate the role of the early antiviral innate immune response in controlling viral replication in ducks, we evaluated the effects of ruxolitinib, a Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway inhibitor known to dampen IFN signalling in mammals. We first optimized a treatment protocol in 2-week-old ducklings and showed that repeated intracoelomic injections of ruxolitinib significantly decreased IFN-stimulated gene (ISG) mRNA levels in the lung, while oral administration was ineffective. In subsequent infection experiments with an H5N9 HPAIV strain, ruxolitinib treatment led to an earlier peak of viral shedding and increased viral RNA levels in respiratory tissues, which however was not associated with increased expression of clinical signs. Analysis of host immune gene expression in the respiratory tract confirmed a transient suppression of ISG expression coincident with ruxolitinib treatment, followed by a recovery once treatment was ceased. This work provides the first demonstration of the effectiveness of ruxolitinib at inhibiting the antiviral innate immune response in birds, causing increased levels of virus replication when administered to HPAIV-infected ducks.

Virus-like particles (VLPs) based on hepatitis B core antigen (HBc) represent an immunogenic and modular platform for epitope presentation. In this study, the VLPs formed by the modified recombinant hepatitis B core antigen from genotype G (HBc/G) were used as carriers for the presentation of a receptor-binding motif (RBM) of the Delta variant of Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2). The RBM was inserted at the C-terminus of the modified HBc/G extended by the addition of a second, specifically modified C-terminal domain of HBc/G. All arginine residues in the extra domain were replaced with glycine, resulting in a 'two-tailed' HBc/G-Gly vector. The resulting HBc/G-Gly-RBM construct successfully formed regular VLPs in Escherichia coli and elicited specific antibody responses in mice. Despite the moderate immunogenicity of the RBM insert compared with the HBc carrier, sera from RBM-VLP-immunized animals exhibited neutralizing activity against MLV particles pseudotyped with the SARS-CoV-2 Delta spike and showed cross-reactivity with receptor-binding domains from the Wuhan and Omicron variants. To enhance the immune response, a replication-deficient Semliki Forest virus (SFV) vector expressing IL-12 was evaluated alone and in combination with the squalene-based adjuvant AddaVax. The co-administration of SFV-IL12 and AddaVax modestly improved virus neutralization rates and promoted a Th1 response, characterized by increased IgG2a production and IFN-γ secretion. These findings demonstrate the feasibility of combining classical and genetic adjuvants with the HBc-based VLP platform and provide preliminary insights for further optimization toward more potent and protective SARS-CoV-2 vaccine candidates.

Heat shock protein 70s (HSP70s) are highly conserved molecular chaperones found across all domains of life, where they play essential roles in cellular stress responses. Whilst HSP70 homologues have been previously identified in closteroviruses that have ssRNA genomes, their broader presence and evolutionary history in viruses remain poorly understood. In this study, we conducted a comprehensive search of viral protein databases and identified HSP70 homologues in viruses beyond those with ssRNA genomes, including examples with dsDNA genomes in the class Megaviricete. These viral HSP70s exhibit diverse gene organizations, copy numbers and structural features. Notably, HSP70s of viruses from Megaviricetes showed up to three gene copies per genome and distinct structural motifs, whilst those from closteroviruses displayed higher sequence and structural diversity, suggesting faster evolutionary rates. Structural and phylogenetic analyses revealed two major clusters of viral HSP70s, with dsDNA virus HSP70s closely resembling those of their protist hosts, supporting the hypothesis of horizontal gene transfer. In contrast, ssRNA virus HSP70s formed a distinct, highly divergent group. Our findings suggest multiple independent acquisitions of HSP70 genes by viruses and provide new insights into their evolutionary trajectories and potential functional adaptations.

Human cytomegalovirus (HCMV) poses serious health risks, particularly for immunocompromised individuals. However, the current FDA-approved anti-HCMV drugs face challenges such as drug resistance and significant side effects, underscoring the need for alternative treatment options. Essential oil components (EOCs), including eugenol, thymol and vanillin, are recognized for their therapeutic potential. This study evaluates their antiviral effects against HCMV in epithelial (ARPE-19) and fibroblast (MRC-5) cell lines. Among the EOCs, vanillin demonstrated the highest efficacy, characterized by low toxicity and a high selectivity index in both cell types. Mechanistic differences were noted between the cell lines. In ARPE-19 cells, eugenol showed virucidal activity, inhibited viral entry and suppressed early gene expression (IE-1). Conversely, in MRC-5 cells, eugenol mainly blocked viral entry and exhibited virucidal effects. Thymol was most effective in ARPE-19 cells, where it completely suppressed IE-1 expression as a result of both inhibition of viral entry and a direct disruptive effect on IE-1 expression. In addition, thymol showed an effect on viral replication. In MRC-5 cells, thymol primarily inhibited viral entry and attachment. Vanillin exhibited dual inhibitory activity in both cell lines, blocking viral attachment and entry. In MRC-5, vanillin also appears to affect intermediate processes. Notably, combining EOCs with ganciclovir resulted in synergistic effects. The eugenol/ganciclovir combination was particularly effective in ARPE-19 cells, while thymol/ganciclovir showed enhanced efficacy in MRC-5 cells. These findings suggest that EOCs have significant potential as adjunct therapies to improve antiviral outcomes and address drug-resistant HCMV strains.

The guinea pig with guinea pig cytomegalovirus (GPCMV) is the only small-animal model for congenital cytomegalovirus, a leading cause of cognitive impairment and hearing loss in newborns. GPCMV encodes human cytomegalovirus (HCMV) homologues of viral entry glycoprotein complexes, which are neutralizing-antibody vaccine targets. As with HCMV, GPCMV has two pathways of cell entry (direct and endocytic). Specific viral gH/gL-based complexes are necessary for receptor interaction and cell entry: gH/gL/gO trimer (direct) and pentamer complex (PC) (endocytic). Both pathways also require gB as the fusogenic protein. Direct GPCMV cell entry requires platelet-derived growth factor receptor alpha (PDGFRA), but an endocytic PC receptor remains unknown. We hypothesized that cellular knockout of direct and endocytic receptors would completely block infection, which cannot be achieved by gB-based antibodies. Candidate receptors including neuropilin proteins (NRP1, NRP2) and CD147 present on all established guinea pig cell lines were selected based on importance as common virus receptors or in fetal development. Results demonstrated that NRP2 interacted with PC, unlike NRP1 or CD147, in immunoprecipitation assays and eliminated NRP1/NRP2 heterodimer receptor interaction. The viral trimer only interacted with PDGFRA. Double knockout of PDGFRA/NRP2 completely blocked GPCMV infection. In contrast, the CD147/PDGFRA double knockout had limited GPCMV inhibition, and the single knockout of CD147 had no impact. Knockout of the various receptors had no effect on control HSV-1 infection. Ectopic expression of guinea pig cell receptors restored GPCMV infection but not human NRP2/PDGFRA, indicating a basis for the species-specific barrier for GPCMV and HCMV infection. Overall, results increase the translational relevance of GPCMV for the development of CMV intervention strategies.