Journal of General Virology最新文献

Astroviruses are important aetiological agents of gastroenteritis. Recently, two novel human astrovirus (HAstV) clades, VA and MLB, have been identified. However, the replication cycle of these viruses remains poorly characterized. Among these, the novel astrovirus VA1 has been of particular interest due to its reported association with neurological disease in immunocompromised patients. Previous studies have demonstrated that a functional proteasome is essential for the efficient replication of classic HAstVs. In this study, we investigated the role of the proteasome in the replication of HAstV-VA1. We assessed the impact of two proteasome inhibitors, MG132 and bortezomib, on viral replication. Both inhibitors significantly reduced viral protein and infectious progeny production in a dose-dependent manner. Our findings indicate that the inhibitory effects of these compounds are mediated through a mechanism affecting virus entry and a post-entry step in the viral replication cycle during the virus replication cycle.

Laboratory of genetics and physiology 2 (LGP2, also known as DHX58) is unique among members of the RIG-I-like receptor (RLR) family as it lacks the caspase activation and recruitment domain. Although LGP2 per se cannot directly activate downstream antiviral signalling, it plays important regulatory roles, primarily by modulating innate immune responses mediated by RIG-I and MDA5. However, the detailed mechanisms by which LGP2 is induced in mammalian cells during viral infection remain incompletely understood. Herein, we show that LGP2 is strongly upregulated by dsRNA stimulation or virus infection in cultured human cell lines via TLR3 and RLRs, respectively, and that substantial induction of LGP2 remains when paracrine/autocrine signalling of IFNs and/or inflammatory cytokines is abrogated by genetic deletion or chemical inhibition. The latter observation is in stark contrast to the case of myxovirus resistance proteins, the induction of which is strictly IFN-dependent. Mechanistically, we found LGP2 expression to be upregulated by ectopic expression of IRF3-5D, a phospho-mimetic mutant of activated IRF3, or to a lesser extent, by overexpression of RELA, the p65 subunit of NFκB, in an IFN-independent fashion. Additionally, we demonstrated that this regulation operated transcriptionally at the LGP2 promoter level. Altogether, a fraction of LGP2 induction in viral infection is IFN- and cytokine-independent, highlighting exquisite gene expression control in antiviral innate immunity and representing an evolutionary advantage, which ensures uninterrupted supply of this RLR member protein in host responses to invading viruses in the event that IFN production and/or signalling is disabled by viral means.

CM2 is a single-pass transmembrane protein located in the viral envelope and is essential for the growth of influenza C virus. We previously reported that CM2 is involved in viral genome packaging and uncoating. We also demonstrated that alanine substitutions at residues 47-48, 67-69, 73-75, 85-87 and 113-115 in the cytoplasmic domain of CM2 significantly reduced its expression levels. Herein, we analysed whether these mutations affected viral replication. The alanine-substituted recombinant viruses rCM2-Ala67-69, 73-75 and 85-87 exhibited significantly reduced replication compared with recombinant wild-type viruses (rWT), and the amount of CM2 protein in virions and infected cells was also reduced compared with that in rWT. In addition, the amount of viral RNA within the particles of these mutant viruses was significantly lower than that in rWT. Furthermore, the amount of viral RNA-NP complexes transported into the nucleus of infected cells was reduced in rCM2-Ala73-75 and 85-87 viruses. In contrast, recombinant viruses with mutations at positions 113-115 could not be rescued, and virus-like particles containing this mutation showed suppressed genome packaging and uncoating and reduced expression of the CM2 protein. These results suggested that the cytoplasmic region of CM2 contributes to efficient packaging and uncoating of the genome through its stable expression.

This study reports the discovery of a new konkovirus species, named Lachenalia konkovirus 1 (LaKoV1), from Lachenalia plants in an urban botanic garden in Amsterdam. Using a combination of RNA sequencing (RNA-seq), small RNA-seq and advanced bioinformatics, we identified a segmented, negative-strand RNA virus belonging to the family Konkoviridae. Our findings show significant divergence between this novel virus and known members of the family Konkoviridae, such as tulip streak virus (TuSV) and Lactuca big vein-associated Phlebovirus (LBVaPV), supporting its classification as a distinct species. Notably, the sequence differences found in the conserved 5' and 3' ends of these segments suggest potential co-evolution. Despite the observed genomic distances, there is significant conservation in the RNA-dependent RNA polymerase subdomain, underscoring evolutionary relationships among LaKoV1, TuSV and LBVaPV. Our findings expand the known global virome and highlight the importance of exploring plant viromes in diverse ecological settings to better understand virus evolution and diversity.

Reptarenaviruses cause boid inclusion body disease that can affect the fitness of the infected animals through a variety of clinical signs. Reptarenaviruses infect most tissue types in the affected individuals and spread efficiently in captive snake collections. Their genome consists of a small (S) and a large (L) segment, and the reptarenavirus-infected snakes often carry multiple genetically divergent reptarenavirus S and L segments, suggesting reptarenavirus coinfections occur frequently. We previously observed that reptarenavirus S and L segment combinations may vary between the tissues of an infected snake, leading to the hypothesis that the segment combination might contribute to tissue and/or species tropism. To test the hypothesis, we inoculated various cell lines derived from different tissues of several constrictor snake species with two samples containing multiple reptarenavirus segments (F15, two S and seven L segments; F17, one S and four L segments). We blind-passaged both virus samples five times in each cell line and monitored the presence of the segments in the supernatants through reverse transcription PCR. We also passaged the cells following the first inoculation with F17 and studied the segments present as above. The analysis revealed that some L segments were only present in supernatants with a specific S segment, suggesting preferred S and L segment pairs, thereby arguing against free reassortment of the segments. The results also showed that boa constrictor-derived cell lines supported reptarenavirus infection slightly better than pythonid-derived cell lines.

A multivalent vaccine targeting high-consequence infectious diseases in Sub-Saharan Africa (SSA), which are linked to high mortality, morbidity and overlapping clinical manifestations, would significantly improve health security and economic stability in this region. Trivalent vector vaccines were devised to deliver digitally optimized versions of Orthoebolavirus, Orthomarburgvirus glycoproteins (GPs) and a Lassa mammarenavirus (LASV) nucleoprotein (NP) by a single Modified Vaccinia Ankara (MVA) known to protect against mpox virus (MPXV) along with a matched DNA vaccine. Three immunizations in mice and Hartley guinea pigs with MVA only or a DNA prime followed by two MVA administrations induced comparable levels of binding antibodies and LASV-specific T-cells, respectively. While DNA priming mitigated MVA-specific antibody responses, GP- and NP-specific antibodies developed already after a single MVA vaccination. Although a post-outbreak Ebola virus vaccine is available, outbreaks by other filoviruses, annual LASV epidemics and increased incidence of MPXV infections support the rationale for an MVA-based trivalent haemorrhagic fever vaccine for endemic and high-risk human populations in SSA.

Human cytomegalovirus (HCMV) is a ubiquitous human pathogen of high clinical relevance. In terms of pathogenic determination, the regulatory factors of HCMV-host interaction play a crucial role, and recently we reported on virus-supportive functions of the cellular peptidyl-prolyl cis/trans isomerase Pin1. Notably, Pin1 is able to recognize phosphorylated serine/threonine-proline motifs and regulate the structural conformation, stability and function of its substrate proteins. During HCMV replication, Pin1 facilitates viral nuclear egress by inducing site-specific rearrangements of the nuclear lamina through the cis/trans conversion of lamin type A/C. To this end, we developed readout systems to decipher details of HCMV-Pin1 regulatory interaction. Notably, together with primary human foreskin fibroblasts (HFFs) and recombinant lamin-modified cell populations, the molecular mechanisms of Pin1 interaction with both the nuclear lamina and viral proteins were illustrated. Our new results demonstrate the following: (i) currently available Pin1-inhibitory small molecules, similar to the antiviral drug maribavir (MBV), exert an antiviral activity against human and non-human primate cytomegaloviruses (CMVs); (ii) site-specific phosphorylation at serine 22, a Pin1 recognition motif within lamin A/C, is consistently mediated by the pUL97 kinase homologs of these viruses; (iii) the phosphorylation of serine 22 is sensitive to the virus-specific kinase inhibitor MBV; (iv) a doxycycline-inducible expression of autofluorescent lamin A/C-red fluorescent protein (RFP) fusion constructs in HFFs supports the productive HCMV replication; (v) these lamin A/C-RFP reporter cells indicated a virus-induced formation of lamina-depleted areas (LDAs), dependent on serine 22 but independent of the infecting CMV species; and (vi) treatment of CMV-infected cells with kinase or Pin1 inhibitors exerted distinct effects on the magnitude of LDA formation. Combined, the study is consistent with our concept that the mode of nuclear egress shows parallels between human and non-human primate CMVs. Thus, the role of Pin1 may play an important regulatory role in determining virus infection and replication efficiency.