Journal of General Virology最新文献

Understanding the genomic diversity of the Mpox (formerly known as 'monkeypox') virus (MPXV) is important for monitoring viral evolution and dissemination. We encountered three clinical cases in our hospital during the outbreak period of Mpox in 2023 in Japan. The present study aims to report the largest genomic rearrangement observed to date in one of the clinical isolates and to demonstrate its viability in cell culture. Whole-genome sequencing and digital PCR were used to characterize the viral genomes. Viral isolation, microscopic observation and growth kinetics in Vero cells were performed to confirm viral replication. All three patients were men living with human immunodeficiency virus (HIV) and presented typical Mpox symptoms, such as rash, fever and pustules on the body surfaces, including near the genitals. Virus isolation was successful in all three cases. All viral strains belonged to clade IIb, lineage C.1. Notably, one strain exhibited a large-scale genomic rearrangement: a 5.5 kb deletion at the left variable region replaced by a 30.5 kb inverted sequence, the largest reported in clinical isolates. Despite this extensive genomic change, the strain maintained robust replication capacity and marked fusogenicity in vitro. We report, for the first time in clinical isolates, a massive genomic rearrangement in MPXV that does not impair viral replicability. This finding represents an example of genomic plasticity and provides a rare but noteworthy resource for future studies. Taken together, when performing genomic analyses of MPXV, aberrant genomic rearrangements should also be carefully considered alongside single-base substitutions.

Hepatitis C virus (HCV) is often associated with chronic liver diseases and significant alterations in host cellular signalling. However, the molecular mechanisms underlying HCV-related liver pathogenesis remain to be elucidated. The Hippo signalling pathway, a key regulator of cell proliferation and survival, plays a critical role in maintaining liver homeostasis. Here, we investigated the role of the Hippo pathway in HCV-related pathogenesis. We demonstrated that HCV infection induces degradation of LATS1, a key regulator of the Hippo pathway. Degradation of LATS1 protein was restored by a proteasomal inhibitor, but not a lysosome inhibitor, indicating that HCV promotes proteasomal degradation of LATS1 protein. HCV-induced degradation of LATS1 protein was suppressed in si-Itch-transfected Huh-7.5 cells. These results suggest that Itch ubiquitin ligase is involved in ubiquitin-dependent degradation of LATS1 protein. Cell fractionation assays and immunofluorescence staining revealed that HCV infection promoted nuclear translocation of YAP1 protein, suggesting that HCV infection suppresses the Hippo pathway. Furthermore, the transcription of YAP1 target genes, CYR61 and CTGF, that are involved in tissue remodelling and proliferation, was upregulated in HCV-infected Huh-7.5 cells and in HCV-infected patients. Taken together, we propose that HCV promotes the ubiquitin-dependent proteasomal degradation of LATS1 protein, leading to suppression of the Hippo pathway, thereby upregulating transcription of CYR61 and CTGF genes, which may contribute to HCV-related pathogenesis.

Feline morbillivirus (FeMV), first identified in 2012, is a member of the genus Morbillivirus. Like other morbilliviruses, FeMV utilizes signalling lymphocytic activation molecule (CD150 or SLAMF1) as a cellular receptor; however, it is genetically distinct and notable for its unique tissue tropism, particularly its ability to establish persistent infections in the feline kidney. In this study, we established a plaque assay system using Vero cells stably expressing feline SLAMF1 and quantitatively evaluated neutralizing antibodies against FeMV in the sera of domestic cats. The results showed that FeMV-infected feline sera contained exceptionally high titres of FeMV-specific neutralizing antibodies, often far exceeding those observed in animals infected with other morbilliviruses. Importantly, sera with high neutralizing activity against FeMV exhibited undetectable cross-neutralizing activity against other morbilliviruses. In contrast, significant cross-neutralization was observed among non-FeMV morbilliviruses. These findings indicate that FeMV surface glycoproteins are antigenically distinct, underscoring the immunological uniqueness of FeMV. Moreover, while feline SLAMF1 functions as a receptor for various morbilliviruses, FeMV utilized only feline SLAMF1. These data suggest that the receptor-binding domain of FeMV is uniquely adapted to the feline SLAMF1. This study offers valuable tools and insights for FeMV research, advancing our understanding of its antigenicity and host receptor usage.

Prion diseases manifest clinically in three different forms. Sporadic and infectious forms of prion disease are caused by the conversion of WT, cellular prion protein (PrP^C) into its pathogenic conformer (PrP^Sc). In contrast, genetic forms of prion diseases are caused by mutations in the PrP sequence that promote mutant PrP^Sc formation. When reconstituted with either polyanionic or lipid cofactors, purified PrP^C substrate can be converted in vitro into PrP^Sc products that display high levels of specific infectivity when inoculated in WT hosts. In contrast, various protein-only PrP^Sc molecules formed in the absence of cofactors display much lower levels of specific infectivity. Here, we report that protein-only PrP^Sc molecules with different sequences can induce the formation of proteinase K-resistant PrP^Sc molecules and spongiform degeneration in the brains of knock-in mice expressing PrP harbouring the pathogenic E200K mutation, but not in hosts expressing WT PrP. These results indicate that the E200K mutation enhances host susceptibility to various protein-only PrP^Sc fibrils, suggesting fundamental differences in the replication mechanisms of WT versus mutant prions.

Curly top disease (CTD) affects sugar beet, tomato and other crops, resulting in stunted plants with severely curled leaves and reduced yields. The disease occurs worldwide and is caused by geographically associated monopartite geminiviruses transmitted mostly by leafhoppers. However, the aetiology of CTD in South America remains unknown because the disease disappeared in the 1950s. Here, we describe how the chance finding of tomato plants with CTD-like symptoms in Brazil in 2016 and high-throughput sequencing helped identify a novel ~2.6 kb geminivirus DNA associated with curly top disease in Mato Grosso (GV-CTD-MT) that induced CTD symptoms in agroinoculated tomato and Nicotiana benthamiana Domin. plants and produced geminivirus-like virions in infected plants. Evidence GV-CTD-MT may be the genomic DNA of the historic Brazilian curly top virus (BraCTV) includes (i) occurring in the same geographic location (Brazil); (ii) inducing nearly identical CTD symptoms in tobacco (Nicotiana tabacum L.) and tomato plants to those described in the 1940s for the BraCTV; (iii) inducing CTD in a similar broad host range of plant species as previously reported for BraCTV based on leafhopper transmission experiments; (iv) the co-phylogenetic analysis predicting the vector of GV-CTD-MT is Agallia sp. leafhoppers; and, importantly, (v) transmission experiments showing Agallia albidula, the known vector of BraCTV, is a competent vector of GV-CTD-MT. Sequence and phylogenetic analyses revealed that this novel CTD-inducing geminivirus has a chimeric genome, a long evolutionary history, and is closely related to monopartite geminiviruses recently identified in South America. These viruses were placed in the new genus Topilevirus, the fifth genus whose members induce CTD. Thus, our results suggest that BraCTD, which disappeared over 70 years ago, and possibly historic CTDs of sugar beet in South America were caused by topileviruses transmitted by indigenous leafhoppers, thereby solving the conundrum left by first-generation researchers.

Despite their great agronomic interest and widespread occurrence in germplasm resources, the quantitative resistance and tolerance of plants to their parasites have rarely been studied in terms of durability potential. Using experimental evolution under controlled conditions for 9 months, we compared the evolution of potato virus Y (PVY) (Potyvirus yituberosi) virulence, measured by the effect of viral infection on plant fresh weight, and replicative fitness, measured by systemic viral load, in five pepper (Capsicum annuum) lines contrasting in their levels of quantitative resistance and tolerance. PVY evolutionary trajectories differed between pepper lines. Three lines revealed either an increase in PVY replicative fitness or an increase or decrease in PVY virulence. Two other lines did not reveal any significant change in PVY replicative fitness or virulence. The tolerance level of three pepper lines also differed significantly when measured with initial and evolved PVY populations, often associated with changes in PVY virulence. PVY evolutionary trajectories were partly explained by parameters linked to plant resistance operating at different stages of infection (inoculation, colonization of inoculated leaves and systemic infection). This study provides information on the durability potential of quantitative resistance and tolerance to PVY in pepper.

Objective. This study aims to characterize the 20-year trends in human immunodeficiency virus 1 (HIV-1) subtypes and circulating recombinant forms (CRFs) in China, as well as patterns of transmitted drug resistance (TDR) to antiretroviral therapies commonly used in clinical practice.Methods. We analysed HIV-1 sequences from 81,563 individuals living in China between 2003 and 2024. Subtypes and CRFs were classified using COMET V2.4. Among these, pol gene sequences from 41,486 treatment-naïve individuals were used to assess TDR via the Stanford HIVdb genotypic resistance interpretation program.Results. Over the past two decades, CRF01_AE (43.9%) was the most prevalent HIV-1 strain in China, followed by CRF07_BC (19.0%), subtype B (12.3%), subtype C (8.4%) and CRF08_B (4.9%). However, subtype and CRF distributions varied considerably across provinces. CRF01_AE predominated in provinces such as Liaoning (92.4%), Guangxi (58.7%), Beijing (47.7%) and Hainan (44.8%), while CRF07_BC was dominant in Sichuan (63.6%), Chongqing (53.2%) and Xinjiang (82.7%). TDR analysis revealed elevated resistance to non-nucleoside reverse transcriptase inhibitors in certain provinces, including Yunnan (12.4%), Xinjiang (8.2%), Anhui (7.6%) and Henan (6.7%). In contrast, resistance to nucleoside reverse transcriptase inhibitors and integrase inhibitors remained low (<1%) across all regions. Notably, the TDR rate exceeded 5% for several regimens freely provided in China, including AZT+3TC+NVP (6.8%), AZT+3TC+RPV (8.0%), AZT+3TC+EFV (6.4%), TDF+3TC+NVP (6.0%), TDF+3TC+RPV (7.2%) and TDF+3TC+EFV (5.7%).Conclusion. Continued surveillance of HIV-1 genotypes and CRFs is critical, particularly in regions where routine genotypic testing is not implemented. Personalized antiretroviral regimens are urgently needed in regions with high levels of TDR.

Nipah virus and Hendra virus are highly pathogenic henipaviruses for which there are no approved therapeutics for use in humans. Using recombinant Cedar virus expressing luciferase (rCedV-Luc) as a CL2 surrogate, we screened a library of 2,703 Food and Drug Administration (FDA)-approved compounds, yielding 5 promising candidates: bortezomib, harringtonine, homoharringtonine, ixazomib citrate and lanatoside C. Compounds demonstrated low half-maximal inhibitory concentration (IC₅₀) values of ≤0.45 µM and high selectivity indexes >6 in mammalian cell lines. Time-of-addition studies suggest that these compounds target a post-entry stage of henipavirus replication. This study demonstrates the utility of rCedV-Luc as a surrogate for the antiviral screening of henipaviruses and identification of promising candidates for further investigation and development as henipavirus antivirals.

Deltaviruses are circular, negative-sense RNA agents that replicate autonomously but depend on heterologous envelope glycoproteins for spread. Only partial sequences of deltaviruses had been reported from marsupials. By reanalysing public metatranscriptomes from the Australian fat-tailed dunnart (Sminthopsis crassicaudata), we assemble the first complete marsupial deltavirus genome and test its replication in human and animal cells. The fat-tailed dunnart deltavirus (FtDDeV) is a 1,680-nt circular RNA that folds into a canonical unbranched rod-like structure and encodes a 195-aa delta antigen (FtDDAg). Genomic and antigenomic HDV-like ribozymes are present and conserve catalytic core motifs. Phylogenetic analyses cluster FtDDAg with the Tasmanian devil sequence, and both are quite close to RDAg from the neotropical rodent species Proechimys semispinosus. A dimeric FtDDeV cDNA replicon supports time-dependent DAg accumulation in human, simian, rodent and Tasmanian devil cells, with faster kinetics in rodents and marsupial cells. FtDDAg accumulation patterns in host nuclei show characteristic viral hubs, observed with other deltaviruses. No obvious coinfecting helper viruses were detected in FtDDeV-positive libraries. Our study extends the confirmed host range of deltaviruses to marsupials and provides a replication-competent clone to investigate helper usage, host restriction and deltavirus evolution.

Coronaviruses evolve rapidly, with recombination and mutation fostering the emergence of variant strains. The avian coronavirus infectious bronchitis virus (IBV) is an important poultry pathogen and a valuable natural model for studying coronaviruses. Australian strains have evolved independently of those infecting chickens elsewhere in the world, so understanding the biology and evolution of these strains can further our understanding of factors driving the emergence of novel coronaviruses. We infected groups of specific pathogen-free Leghorn chickens with six Australian IBVs (from five distinct genotypes) isolated between 1962 and 2013. All six affected the respiratory tract, but only one was nephropathogenic (N1/62). All six induced significant lesions and actively replicated in the upper respiratory tract, but they had lower levels of replication and induced less severe lesions in the middle and lower trachea. There were significant differences between the six strains in the severity of the lesions they induced and in their tissue tropism and effect on tracheal ciliary motility. Strains N1/62 (strain T) and N1/03 caused the most severe tracheal ciliostasis and replicated to the highest levels in tissues. Strain N1/03 caused the most severe lesions at 9 days post-infection. Only strain N1/03 caused lesions in the lower trachea. Overall, strains N1/03 and N1/62 were the most virulent. This study is the first to characterize the histological changes induced by the recently isolated Australian IBVs and compare them directly with older strains. Recombination between field and vaccine strains of IBV has yielded emergent IBVs in Australia that appear to have enhanced virulence for the respiratory tract.