Virologica Sinica最新文献

Pseudorabies virus (PRV), a member of the Alphaherpesvirinae subfamily, is the causative agent of Aujeszky's disease, which severely affects swine health and poses a potential zoonotic risk. PRV can evade the type I interferon (IFN-I)-mediated antiviral response, thus enabling persistent infection, yet the molecular basis for this immune evasion remains unclear. Here, we identify a novel role for thymidine kinase (TK), a key PRV virulence factor, in suppressing IFN-I signaling. Ectopic expression of TK markedly inhibited IFNα-induced transcription and expression of interferon-stimulated genes (ISGs), whereas TK-deficient PRV (PRV-ΔTK) showed increased sensitivity to IFN-I, elevated ISG expression, and reduced replication following IFNα treatment. Mechanistic analyses revealed that TK interacts with both Janus kinase 1 (JAK1) and signal transducer and activator of transcription 1 (STAT1), disrupting the JAK1-STAT1 complex formation and impairing STAT1 phosphorylation and downstream ISG induction. This inhibition is mediated by amino acids 107-212 of TK, a region independent of its catalytic site, and is essential for its immunosuppressive activity. These findings uncover a previously unrecognized function of TK in antagonizing the IFN-I response through interference with JAK1-STAT1 signaling. Beyond its established role in nucleotide metabolism and virulence, this immune evasion function may account for the strong conservation of TK among PRV strains. Collectively, our results expand the understanding of PRV pathogenesis and identify TK as a potential target for antiviral intervention.

Hainan Island, located in the South China Sea, is known as an area with diseases related to Rickettsia spp. or spirochete infection; however, the potential threat there from infection with tick-borne viruses (TBVs) remains obscure. In the present study, the dominant tick species, including Rhipicephalus sanguineus and Rhipicephalus microplus, were collected in Hainan Island, and tick viromes were investigated by metagenomic sequencing. In total, 27 viral species were identified belonging to the families Orthomyxoviridae, Flaviviridae, Nairoviridae, Phenuiviridae, Totiviridae, Chuviridae, Rhabdoviridae, and Parvoviridae, amongst which one novel virus and 13 new strains were discovered. Subsequently, individual ticks were screened for seven TBVs, Huanggang Rhabd tick virus 1 (HRTV1), Lihan tick virus (LHTV), Mivirus (MIV), Guangdong tick quaranjavirus (GTQV), Wenchang Ephemerovirus (WEPMV), Jingmen tick virus (JMTV), and brown dog tick phlebovirus (BDPTV), resulting in high prevalence rates of 16.97%, 9.59%, 10.33%, 7.38%, 7.01%, 6.27%, and 3.69%, respectively. While co-infection with multiple viruses was more frequent in R. sanguineus, R. microplus ticks generally had higher viral loads. Four febrile patients showed antibody responses to three TBVs, one each to LHTV and JMTV, and two to GTQV; the patient with antibodies to JMTV also showed neutralizing activity against this virus. This study promoted our understanding of the diversity and complexity of the TBV community in Hainan Island. The results provide serological evidence that human exposure to TBVs like JMTV may have occurred in Hainan, raising concern about potential risks from TBVs and the need to perform further surveys of TBVs among ticks, animals and humans.

With an unexpected increase of human metapneumovirus (hMPV) cases in northern China since late 2024, concerns arose whether novel hMPV variants triggered this epidemic. Utilizing the Beijing Respiratory Pathogen Surveillance System (RPSS), we conducted a genomic evolutionary analysis spanning 2014-2024 and revealed genetic information for the strains that caused the high rates of hMPV outbreaks during this period. To clarify the epidemic drivers and evolutionary characteristics of the hMPV strains circulating in Beijing, phylogenetic, population dynamic and mutation analyses were performed using high-quality complete sequences from both this study and publicly available data. A total of 348 high-quality hMPV genomes were obtained by next-generation sequencing (NGS), all of which belonged to four known clades: A2b1, A2b2, B1, and B2. Before 2024, A2b2 predominated in Beijing; however, a shift to clade B2 was observed starting in late 2024. In addition, a phylogenetically independent lineage Ⅰ was identified in this study, accounting for 93.1% of B2 genomes collected since late 2024. Furthermore, we identified several unique nonsynonymous mutations in viruses within lineage I that may have phenotypic implications. Our findings indicate that lineage I of clade B2 was the major cause of the unusual increase in hMPV outbreaks in Beijing in late 2024, with no evidence of an emerging novel variant. Although our data were only restricted to samples from Beijing, the findings are likely representative of the hMPV surge across northern China in 2024, given city's high population density and mobility.

Swine enteric coronaviruses (SECoVs) cause severe watery diarrhea and high mortality in piglets, resulting in significant economic losses to the global pig industry. However, frequent mutations in SECoVs significantly compromise vaccine-induced immunity and limit cross-protection against emerging variants. Therefore, there is an urgent need to develop new broad-spectrum antiviral drugs to be the last line of defense to supplement vaccine immunity. In this study, we utilized molecular docking and molecular dynamics simulations to identify phloretin as a broad-spectrum SECoV inhibitor. Phloretin has demonstrated prophylactic and therapeutic efficacy in vitro and in vivo, improving the survival of SECoV-infected piglets. It was further found that phloretin exerts a broad-spectrum antiviral effect by acting on the conserved 3CLpro Cys144 site of three SECoVs. It is worth noting that derivative A12, designed on the basis of the structure-activity relationship (SAR) between phloretin and 3CLpro, showed a 15.7, 2.6, and 8.4-fold increase in antiviral effect against porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), and porcine delta coronavirus (PDCoV), respectively. This study reveals a 3CLpro Cys144 targeting broad-spectrum strategy for use against SECoVs, providing a candidate drug to bridge the vaccine immunity gap.

Despite widespread use of multiple PCR, a substantial proportion of pediatric acute respiratory tract infections (ARTIs) lack identifiable pathogens and are classified as unknown etiology. The microbial characteristics and clinical relevance of these cases remain unclear. In this study, we compared the airway microbiomes of PCR-positive and PCR-negative ARTIs and examined their relationships with sampling site and disease severity. A total of 514 hospitalized children with ARTIs were enrolled. Nasopharyngeal swabs (NS) and bronchoalveolar lavage fluid (BALF) samples were tested using a 22-target multiplex PCR panel and subsequently stratified by pathogen status for pooled metatranscriptomic sequencing to profile active microbial communities, viral genotypes, and antibiotic resistance genes. PCR identified common respiratory pathogens in 77.0% of NS and 54.1% of BALF samples. Metatranscriptomic analysis showed that PCR-negative pools displayed markedly lower viral activity and comparatively higher bacterial transcript abundance, with notable enrichment of Pseudomonas. Microbial signatures differed between upper and lower airway samples and across clinical severity, with severe cases demonstrating increased bacterial burden and Pseudomonas enrichment, whereas mild infections exhibited relatively stronger viral signals. Under current thresholds, antibiotic resistance genes were detected in patient pools but not in healthy controls. Overall, PCR-negative pediatric ARTIs exhibited distinct, bacteria-enriched microbial profiles. Integrating metatranscriptomics with PCR enhances pathogen characterization and reveals site- and severity-related microbial patterns that may support diagnostic evaluation and clinical management.

Influenza A virus (IAV) is one of the most important zoonotic pathogens and can cause global influenza pandemics and seasonal influenza outbreaks. Generation of recombinant IAV expressing a fluorescent protein will allow the infection to be easily monitored. In this study, we initially constructed a replication-defective H1N1/ΔPB2-GFP and a replication-competent H1N1/NS-GFP. However, these two reporter IAVs exhibited genetic instability. To stabilize the recombinant viral genome, we recoded the gfp sequence (rGFP) using synonymous codons to mimic the high-NP-binding regions involved in NP-vRNA interaction. This approach resulted in the development of replication-defective H1N1/ΔPB2(300)-rGFP and replication-competent H1N1/NS-rGFP, both of which exhibited enhanced stability in GFP expression. By replacing the HA segment from strain A/mink/China/CY 2017 (H5N1), we also generated a replication-defective H5N1/ΔPB2(300)-rGFP, which showed excellent genetic stability. Using these reporter IAVs, the blocking of virus infection by neutralizing antibodies and antivirals can be rapidly detected by the loss of fluorescent reporter expression. Replication-defective reporter IAVs constructed in this study can only infect and replicate in cells expressing PB2, allowing the possibility of manipulation of highly pathogenic IAV and their related reassortant strains in biosafety level-2 laboratories. Our data highlight the importance of NP-vRNA interaction for the stability of IAV genome, and the reporter IAVs generated using this strategy could be powerful tools for both basic and applied influenza virus research.

Zika virus (ZIKV) infection is associated with severe neurological complications such as congenital microcephaly, yet no safe and effective vaccine is currently available. A critical challenge in ZIKV vaccine development arises from cross-reactive, non- or sub-neutralizing antibodies, which may enhance dengue virus (DENV) infection through antibody-dependent enhancement (ADE). Herein, we report a vaccine strategy utilizing Mi3 nanoparticles to display the envelope (E) protein domain III (EDIII) of ZIKV, which induces protective immunity against ZIKV infection in murine models. Compared to an EDIII subunit vaccine, the Mi3-EDIII nanoparticle vaccine elicited significantly higher antibody responses and stronger cell-mediated immune responses. In C57BL/6 mice, maternal immunization with Mi3-EDIII protected the neonates against ZIKV-caused symptoms, including body weight loss, neurological abnormalities, retardation of brain development, and mortality. In interferon-α/β receptor knockout (Ifnar1^-/-) C57BL/6 mice, Mi3-EDIII immunization conferred effective protection against lethal ZIKV challenge. Notably, unlike ZIKV convalescent sera, Mi3-EDIII immune sera did not enhance DENV infection in human chronic myelogenous leukemia K562 cells, suggesting the absence of ADE-prone antibody induction. Our results demonstrate that Mi3-EDIII is a promising vaccine candidate against ZIKV infection and warrants further development.

With an increasing number of human adenoviruses identified, the selection of potential therapeutic vectors broadens. For safety reasons, achieving cell-specific gene delivery is crucial to minimize off-target effects. Therefore, it is essential to gain a systematic understanding of adenovirus receptor-usage. Our aim is to establish a human-originated in vitro model for comparative analysis of human adenoviruses receptor usage. Based on our previous work of human CD46 and coxsackievirus and adenovirus receptor (CAR) knockout cell lines, we generated desmoglein 2 (DSG2) knockout cell lines using genome-engineering technology based on Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated protein 9 (CRISPR/Cas9). All together, we established a panel of cell lines that carry a single, double, or triple knockout of the three major human adenovirus receptors: CAR, CD46 and DSG2. Notably, cell proliferation speed was affected by the CAR-knockout, but not the DSG2-or CD46-knockouts. In addition, the spheroid formation ability was sharply reduced in CAR- or DSG2-knockout cells, but not the CD46-knockout cells. With this receptor-knockout model, we confirmed the receptor usage of nine species B adenoviruses. Furthermore, adenovirus vectors containing a previously identified DSG2-binding affinity-enhanced mutation showed DSG2-dependent cell entry within this cell model, which indicates that they are de-targeted from CD46 - the ubiquitously expressed receptor on all nucleated cells. Collectively, our findings show that the adenovirus major receptor knockout cell lines can serve as an in vitro model to help select adenovirus types suitable for individual applications and to better understand adenovirus infection biology.

Emerging zoonotic infectious diseases, predominantly caused by viruses, pose increasing public health threats globally. Rodents and shrews are natural hosts for a variety of zoonotic viruses. Guangzhou is one of China's most densely populated cities and experiences frequent international and domestic population movements, making it a hotspot for infectious diseases. This study reports the metatranscriptomics virome of 208 rodents and shrews collected between June 2023 and December 2024 from four main urban areas (Tianhe, Baiyun, Liwan, Yuexiu) and five non-main urban areas (Zengcheng, Huadu, Conghua, Panyu, Nansha) in Guangzhou. Individual libraries were constructed from mixed tissue samples (liver, spleen, lung, and kidney) of each animal. Metatranscriptomics sequencing revealed diverse viral communities, identifying 24 viral strains across eight mammalian-associated viral families. Notably, we identified 17 known viruses and seven potentially novel viruses, including Seoul virus (5.2% prevalence in Rattus norvegicus from Panyu), Wenzhou mammarenavirus (13.2% in Rattus norvegicus from Conghua and Huadu), Jeilongvirus (29.4% in Rattus andamanensis from Panyu), and a divergent lineage of arteriviruses that may represent a new genus (maximum positivity rates of 2.9% in Rattus norvegicus and 5.7% in Rattus tanezumi). Phylogenetic analysis elucidated evolutionary relationships within key families such as Hantaviridae, Arenaviridae, Flaviviridae, and Parvoviridae, revealing distinct viral carriage patterns in Guangzhou City that are shaped by host species and geographical location. This is the first macro-level study of rodent and shrew viromes in Guangzhou and provides a scientific basis for strengthening surveillance of mammalian-associated viruses and preventing emerging zoonotic infectious diseases in the region.