Journal of General Virology最新文献

Tomato spotted wilt virus (TSWV) is a highly destructive plant pathogen transmitted by thrips, including Frankliniella occidentalis, in a circulative and propagative manner. To counter viral infections, thrips activate antiviral defences through C20 oxygenated polyunsaturated fatty acids (PUFAs), known as eicosanoids. However, at later stages of infection, C18 PUFAs, including epoxyoctadecamonoenoic acids (EpOMEs), modulate immune responses by preventing excessive and unnecessary activation. Our previous study demonstrated that TSWV elevates EpOME levels in thrips to suppress antiviral responses and enhance viral replication, with its nonstructural protein S (NSs) playing a key role in this process. In this study, we investigated the impact of NSs protein variation on vector immunity and virus-vector interactions. We assessed relative TSWV titres in thrips larvae and examined the role of eicosanoids, specifically 12,13-EpOME and PGE₂, in regulating viral load and apoptosis. Our results revealed that 12,13-EpOME significantly increased viral titres, whereas PGE₂ reduced the viral accumulation by promoting apoptosis in the vector insect. Phylogenetic analysis identified distinct NSs variations among TSWV isolates, with resistance-breaking (RB) and WT strains, which modulated differential infection patterns in thrips gut tissues, as visualized through fluorescence in situ hybridization. RB strains exhibited significantly higher viral titres, along with increased expression of EpOME biosynthetic gene (Fo-CYP24) and decreasing expression of EpOME degradation gene (Fo-sEH2). Apoptosis assays using the terminal deoxynucleotidyl transferase dUTP nick-end labelling assay further indicated that RB strains suppressed the gut epithelial cell death in thrips by antagonizing a process regulated by PGE₂. Additionally, in vivo transient expression of the NSs gene in a nontarget insect, Spodoptera exigua, demonstrated the immunosuppressive effects by inducing EpOME level through upregulation of Se-CYP expression and downregulation of Se-sEH expression. Indeed, RB strains suppressed cellular immune responses more effectively than WT strains in S. exigua. These findings provide novel insight into the role of NSs genetic variation in TSWV transmission in the insect vector as well as in the host plants.

Vertical transmission of human cytomegalovirus (HCMV) during pregnancy is a major cause of congenital disease. In the absence of robust vaccination strategies, antiviral drug regimens are being developed to inhibit the vertical transmission of the virus. Recent clinical data have indicated that valaciclovir, an orally bioavailable form of aciclovir, was effective at limiting vertical transmission of HCMV when administered during pregnancy. However, there is no widely cited in vitro analysis of valaciclovir's antiviral effect against HCMV, and it is possible, like aciclovir, that valaciclovir has poor anti-HCMV activity. The antiviral effects of aciclovir and valaciclovir against HCMV were compared to the widely used anti-HCMV drug ganciclovir. Compared to ganciclovir, the anti-HCMV effects of either aciclovir or valaciclovir were poor, and robust anti-HCMV activity in all cell lines tested (adult fibroblast, foetal fibroblast or trophoblast cells) was only observed at high drug concentrations. All drugs had no obvious effects on the viability of uninfected cells. Overall, valaciclovir had poor anti-HCMV activity, and its anti-HCMV efficacy upon administration during pregnancy may rely on a combination of factors. These data argue for the continued development of valaciclovir and anti-HCMV compounds to inhibit vertical virus transmission.

Rabies is a fatal zoonosis that impairs host immune function, yet effects on peripheral lymphoid architecture are poorly defined. During a 2021-2022 rabies virus (RABV) outbreak in South Africa, we collected cervical lymph nodes from 36 rabies-suspect dogs; RABV RNA was detected in 27. Canine distemper virus RNA was detected in a subset across both RABV-positive (RABV+) and RABV-negative (RABV-) groups and was not associated with clinical-sign count. We set up a computer-assisted histological analysis tool to quantify germinal-centre (GC) nucleus density and immunohistochemistry for CD20, PNA and IBA1 to profile B cells, GC activity and macrophages. Within the outbreak cohort, GC density and marker-based metrics did not differ between RABV+ and RABV- dogs. Two healthy dogs were included as reference tissues; values in outbreak dogs were generally lower, but these contrasts are contextual given the limited, non-matched controls. This study provides a reproducible framework for quantifying immune cell organization in field-collected tissues during natural RABV exposure and highlights the need for larger, geographically matched control groups and complementary functional immune measurements.

Plant virus infections pose a substantial threat to crop quality and productivity, contributing to considerable economic losses in global agriculture annually. Traditionally, laboratories have widely adopted serological techniques, such as ELISA, and molecular methods, including quantitative PCR, for virus diagnostics. More recently, sophisticated next-generation sequencing approaches have been introduced to improve the efficiency and reliability of virus detection and identification. However, the development of sensitive, rapid and low-cost methods for the on-site detection, quantification and identification of plant viruses remains an ongoing challenge and is still in its early days. Point-of-care technologies have not fully realized their potential in agriculture due to numerous challenges, such as the elevated cost of development, lack of standardized validation and insufficient field testing. Therefore, future success depends on addressing these technical, economic and regulatory hurdles, as well as considering the specific user needs within the agricultural context. In this mini-review, recent advancements in biosensing for on-site plant virus monitoring, involving nanotechnology-based sensors, clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems, electrochemical and modern field-effect transistor-based sensors offering high sensitivity, speed and portability, are discussed. These technologies, when integrated with smartphone applications and/or machine learning modules, could enable real-time, field-deployable diagnostics for early disease management and sustainable agriculture. The aim is to raise awareness among plant virologists about this panel of emerging diagnostic concepts that could help improve current methods, ultimately facilitating the management of plant viral diseases.

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.