Archives of Virology最新文献

Japanese encephalitis virus (JEV) poses a significant public health risk due to the lack of effective antiviral therapies. To identify novel antiviral agents, we evaluated the antiviral activity of ethanol extracts and organic solvent fractions derived from the roots and stems of hemp (Cannabis sativa L.). Noncytotoxic concentrations of the extracts and fractions were determined using in vitro cytotoxicity assays. At these concentrations, several fractions demonstrated potent virucidal activity, with the hexane and chloroform fractions showing the strongest effects. Post-treatment of virus-infected cells with these fractions significantly suppressed viral replication, as evidenced by reduced JEV mRNA and E protein expression. In contrast, pre-treatment or co-treatment did not yield notable antiviral effects. GC-MS analysis revealed the presence of multiple known hemp-derived compounds in the active fractions. Among them, stigmasterol exhibited strong virucidal and antiviral activity. It inhibited viral entry and growth when applied during or after infection and significantly decreased viral mRNA and E protein levels in infected cells. These findings suggest that stigmasterol contributes to the antiviral effects of hemp extracts and may be one of the active compounds responsible for inhibiting JEV replication. This study highlights the potential of hemp-derived natural products, particularly stigmasterol, as promising candidates for the development of antiviral agents against JEV infection.

In this study, we identified and characterized two mycoviruses from the Nigrospora oryzae strain WK-26: Nigrospora oryzae mitovirus 4 (NoMV4) and Nigrospora oryzae botoulivirus 1 (NoOLV1). The genome of NoMV4 is 2529 nucleotides in length, containing a single open reading frame (ORF) that encodes an RNA-dependent RNA polymerase (RdRp). BLASTp analysis revealed that NoMV4 shares the highest sequence similarity (53.06% identity) with Fusarium graminearum mitovirus 1. Phylogenetic analysis indicated that NoMV4 belongs to the genus Unuamitovirus within the family Mitoviridae. The genome of NoOLV1 is 2951 nucleotides in length and encodes an RdRp protein with the highest sequence similarity (64.46% identity) to that of Nigrospora sphaerica ourmia-like virus 1. Phylogenetic analysis suggested that NoOLV1 is a new member of the genus Deltascleroulivirus within the family Botourmiaviridae. This is the first report of the complete genome sequence of a botoulivirus in N. oryzae.

The SARS-CoV-2 nucleocapsid (N) protein plays a pivotal role in disrupting host cellular processes by interfering with G3BP1, a key stress granule protein involved in RNA binding and metabolic regulation. Using RNA immunoprecipitation coupled with nanopore sequencing, we found that the N protein significantly alters the RNA interactome of G3BP1, particularly reducing binding to transcripts involved in fatty acid metabolism, such as ACOT12, PLIN4, GPX1, and ACADS. This disruption leads to dysregulation of lipid homeostasis and stress granule assembly, suggesting a strategy of the virus to reprogram host metabolism for its advantage. We also found that the N protein of the Wuhan strain exhibits stronger G3BP1 binding than that of the Omicron variant, potentially contributing to differences in pathogenicity. Mendelian randomization identified dihomolinoleate (20:2n6), an omega-6 polyunsaturated fatty acid, as a protective factor against severe COVID-19, while 4-androsten-3beta,17beta-diol disulfate, a steroid hormone metabolite, was associated with increased disease severity. These findings highlight the critical role of lipid metabolism in COVID-19 pathogenesis. The upregulation of the dihomolinoleate metabolic pathway genes in COVID-19 patients further underscores the importance of metabolic reprogramming during infection.

The 5’ end of the orthoflavivirus genome contains a stem-loop structure, known as stem-loop A (SLA), which interacts with the viral polymerase (the NS5 protein) and functions as the promoter during RNA replication. Previously, we replaced the SLA of Zika virus (ZIKV; a mosquito/vertebrate orthoflavivirus) with the corresponding region of Long Pine Key virus (a dual-host-associated insect-specific orthoflavivirus), producing a chimeric virus capable of replicating in both mosquito and vertebrate cells. Here, we investigated whether additional chimeric viruses could be created by replacing the SLA of ZIKV with those of other orthoflaviviruses that are maintained in different transmission cycles, namely: tick-borne encephalitis virus (TBEV; a tick/vertebrate orthoflavivirus), Culex flavivirus (a classical insect-specific orthoflavivirus), Modoc virus (a rodent-associated vertebrate-specific orthoflavivirus), and Rio Bravo virus (a bat-associated vertebrate-specific orthoflavivirus). Exchanging the SLA of ZIKV with that of TBEV produced a chimeric virus capable of replicating in mosquito and vertebrate cells, whereas the other SLA replacements did not yield infectious virus. The chimeric virus replicated more slowly, reached lower titers, and produced smaller plaques than wild-type ZIKV in vertebrate cells. The chimeric virus also exhibited reduced fitness in mosquito cells. These findings demonstrate that replacement of the SLA of ZIKV with the corresponding region of TBEV produces a chimeric virus that replicates in both mosquito and vertebrate cells, revealing that ZIKV NS5 is able to recognize and bind to the TBEV promoter, rendering it active. This study highlights the importance of SLA–polymerase compatibility in flavivirus replication and provides insight into the molecular basis of host adaptation.

Through virome sequence analysis of the rice blast fungus Magnaporthe oryzae strain HM278, a novel positive-sense single-stranded RNA (+ssRNA) virus was identified and designated as "Magnaporthe oryzae botourmiavirus 13" (MoBV13). The complete genome of MoBV13 is 2,143 nucleotides in length and contains a single open reading frame (ORF) encoding a putative RNA-dependent RNA polymerase (RdRp), consisting of 568 amino acids, with a molecular mass of 62.5 kDa. Sequence comparisons and phylogenetic analysis indicated that MoBV13 is a novel member of the genus Botoulivirus of the family Botourmiaviridae.

African swine fever (ASF) is a significant infectious disease that affects only swine species. ASF was first reported on a pig farm in South Korea in September 2019. As of July 2024, 44 pig facilities and 4143 wild boars in South Korea have been confirmed to be positive for ASF, and ASF is now considered to be endemic in wild boar populations in this country. It is assumed that the infection spread sporadically to pig farms via biosecurity breaches, originating from a nearby source of the virus, probably infected wild boars. In this study, ASF samples collected from eight pig farms between July 2023 and July 2024 were subjected to genetic analysis. All analyzed ASF virus (ASFV) isolates belonged to the p72 and p54 genotype II, CD2v serogroup 8, and the central variable region type 1. Novel multigene family 505_9R/10R (MGF)-V variations were detected in four ASFV isolates from pig farms in the east-central region. Analysis of the intergenic region (IGR) between the I73R and I329L genes showed that three of four MGF-V variants belonged to the IGR-II type, while one isolate was an IGR-III variant. These results provide further insights into the genetic variation and evolution of ASFV spreading in South Korea, highlighting the need to enhance genetic surveillance of ASFV isolates circulating in the country.

Leishmaniasis, which is caused by protozoan parasites belonging to the genus Leishmania remains a public-health concern across the provinces of Iran, necessitating better treatments and control strategies. Leishmania RNA virus (LRV) primarily infects Leishmania major and is known to influence disease severity and drug resistance. In this study, we investigated the presence of LRV2 (LRV type 2 in the Old World) in Leishmania isolates from patients with cutaneous leishmaniasis in Qom, Iran, in 2019–2020. Samples from 15 patients were analyzed for species identification using ITS1-PCR-RFLP and for LRV2 detection using RT-PCR, semi-nested PCR, and Sanger sequencing. The viral load was quantified by qRT-PCR. Of the 15 L. major isolates, nine (60%) carried LRV2. Phylogenetic analysis revealed a close relationship to strains previously reported in Golestan province. Given the large number of travelers in Qom, the detection of LRV2 underscores the need for ongoing surveillance and further research into its role in leishmaniasis transmission, clinical outcomes, and drug resistance.

Xenarthrans face increasing viral threats from anthropogenic pressures and domestic animals. In this study, we investigated the presence of coronaviruses, paramyxoviruses, and poxviruses in anteaters and armadillos from Brazilian biomes. We screened 236 individuals for these viruses by molecular methods. Canine distemper virus (CDV) was identified in four giant anteaters and one six-banded armadillo. A poxvirus, showing 88% sequence identity to molluscum contagiosum virus, was detected in one giant anteater. No coronaviruses were detected. These findings expand our knowledge on the host range of CDV and the circulation of divergent poxvirus in wildlife, with implications for conservation and zoonotic disease surveillance.

Brazilian porcupinepox virus (BPoPV) was recently identified in free-ranging Brazilian porcupines (Coendou longicaudatus) in Brazil. In this study, we investigated the histopathological and ultrastructural features of BPoPV infection in four individuals and documented the occurrence of BPoPV in Goiás state, Brazil, where the virus had not been reported previously. Cutaneous lesions exhibited characteristic poxviral cytopathic changes. Histopathological analysis and transmission electron microscopy (TEM) revealed intralesional poxvirus-like particles, confirming both epithelial and systemic viral tropism. These findings contribute to the current understanding of BPoPV-associated disease and raise concerns regarding its potential impact on wild porcupine populations and conservation efforts.

Using high-throughput sequencing, a novel mastrevirus was discovered infecting the weed Leptochloa chinensis and was designated as "Leptochloa chinensis mastrevirus" (LcMAV). The full genome sequence of LcMAV is a 2825 nt long. Phylogenetic analysis and sequence comparisons revealed that LcMAV is genetically distinct but shares significant sequence similarity with Sporobolus striate mosaic virus 1 (SSMV-1), suggesting a close evolutionary relationship. The LcMAV genome contains four major open reading frames encoding a movement protein (MP), a capsid protein (CP), and two replication-associated proteins (RepA and Rep) and also contains two intergenic regions (IRs). The virus was identified through comprehensive genomic sequencing, utilizing both RNA and DNA extraction methods, as well as rolling-circle amplification (RCA) for recovery of the full genome. These findings emphasize the role of L. chinensis as a host for newly emerging viruses that might endanger nearby rice crops, highlighting the need for enhanced surveillance and monitoring of viral diversity in agricultural systems. This discovery contributes to our understanding of the evolutionary dynamics of the family Geminiviridae and emphasizes the role of weeds in the transmission of viruses to economically important crops.