Virologica Sinica最新文献

Crimean-Congo hemorrhagic fever virus (CCHFV) is a highly pathogenic tick-borne virus that causes severe hemorrhagic fever with high mortality rates in humans. No licensed vaccines or efficacious antiviral therapies are currently available. Here, we identified seven heavy chain antibodies targeting CCHFV Gc, which consist of heavy-chain variable domain (VHH) fused to human IgG1 Fc region (VHH-Fc). These VHH-Fc antibodies exhibited neutralizing activity against both recombinant vesicular stomatitis virus (VSV)-vectored CCHFV pseudoviruses and CCHFV transcription- and entry-competent virus-like particles (tecVLPs). Among these, N025 achieved the most potent pseudovirus neutralization, while N013 showed remarkable efficacy in tecVLP systems, with IC₅₀ values of 22.7 ng/mL and 33.0 ng/mL, respectively. AlphaFold3 structural predictions revealed that all characterized VHH-Fc antibodies target epitopes within Domain II of the Gc protein, with partial or complete overlap with the fusion loop region. Alanine scanning mutagenesis confirmed the functional significance of these epitopes, with N013 showing the highest binding energy change (ΔΔG = 25.36 kcal/mol) and moderate competition with a known fusion loop-targeting antibody. Sequence conservation analysis across representative CCHFV strains from different genetic lineages demonstrated complete conservation of the N013 and N025 epitopes, suggesting potential for broad-spectrum neutralizing activity. Together, our findings provide a novel strategy for developing CCHFV therapeutics and identify promising antibody candidates that could inform future broad-spectrum antiviral development efforts.

The transcription factor Sex-determining region Y-box protein 3 (SOX3) is well known for its critical roles in sex determination and cell differentiation; however, its function in antiviral innate immunity remains unexplored. This study uncovered how SOX3, induced by viral infections, modulates type I interferon (IFN-I) responses. RNA sequencing, quantitative PCR, and immunoblot analysis collectively revealed that SOX3 overexpression suppresses virus-induced interferon beta 1(IFN-β) promoter activation and significantly inhibits the expression of key antiviral interferon-stimulated genes (ISGs), including ISG15 and interferon induced protein with tetratricopeptide repeats 1 (IFIT1). Conversely, the knockdown of SOX3 enhanced IFN-β production and ISGs expression, confirming its role as a negative regulator of antiviral immunity. Mechanistically, chromatin immunoprecipitation sequencing (ChIP-seq) identified SOX3 binding specifically at the AKT serine/threonine kinase 1 (AKT1) locus. Further analysis demonstrated that SOX3 directly upregulates AKT1 expression, subsequently increasing phosphorylation and inactivation of the tumor suppressor phosphatase and tensin homolog (PTEN). Inactivation of PTEN inhibited interferon regulatory factor 3 (IRF3) nuclear translocation, leading to reduced IFN-β expression. Thus, our findings uncover a previously uncharacterized SOX3-AKT1-PTEN signaling axis in the regulation of antiviral innate immunity, providing new insights into immune evasion strategies and highlighting potential therapeutic targets to enhance antiviral responses.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease with high mortality, and clinical practice lacks dynamic tools to assess its rapidly evolving course. This study aims to develop stage-specific machine learning models to predict mortality risk using longitudinal biomarker data. We conducted a retrospective analysis of 5359 laboratory-confirmed SFTS patients from two hospitals in the highly endemic region in China. Serial measurements of 46 clinical and laboratory variables were integrated into a three-stage prognostic model developed using extreme gradient boosting (XGBoost). Within each clinical stage, key predictors and their relative contribution (RC) of mortality risk were assessed. Model performance was assessed based on discrimination, calibration, and decision curve analysis (DCA) in internal and external test sets. XGBoost models were constructed across 10 temporal phases, later consolidated into three clinically distinct stages via hierarchical clustering: early (≤7 days), intermediate (days 8-9), and late (≥10 days). Key predictors included age (dominant in early phase; RC, 18.44%), lactate dehydrogenase (LDH; RC peaking at 60.10% in late phase), and monocyte percentage (RC range from 5.25% to 16.04%). Pathophysiological shifts across clinical stages were revealed: early viral cytopathy (dominated by age and MONO%), intermediate immunopathology (marked by LDH surge), and late hepatic failure (dominated by LDH, AST, and TBA). The model showed strong discrimination (Area under the receiver operating characteristic curve, AUCs: 0.84-0.98 internal; 0.91-0.98 external), calibration (Brier scores: 0.04-0.11), and clinical utility via DCA. This study introduces a dynamic staging system that leverages predictive models and real-time patient data to monitor mortality risk and personalize SFTS care, which enables timely interventions to reduce deaths.

Mosquito-borne flaviviruses, such as Zika virus (ZIKV) and dengue virus (DENV), cause diverse severe clinical manifestations including fever, rash, hepatitis, arthralgia, and congenital anomalies. Here, we identified a host factor, the adaptor protein complex 1 gamma 1 subunit (AP1G1), which plays an important role in both ZIKV and dengue virus 2 (DENV2) infections. We explored the role of AP1G1 in ZIKV and DENV2 infections using CRISPR/Cas9 gene editing technology and RNA interference (RNAi) techniques. Knockout or silencing of AP1G1 decreases the replication of ZIKV and DENV2 in multiple human cell lines. Intriguingly, depletion of AP1G1 results in a significant reduction in ZIKV at an early stage, but decreases DENV2 replication levels during the late stage, suggesting that AP1G1 plays distinct roles in the infection by ZIKV and DENV2. Furthermore, we determined that AP1G1 mediates ZIKV-endosomal membrane fusion through inhibitor experiments and fluorescence labeling assays. Mechanistically, we found that AP1G1 exerts its pro-viral effect through binding to the ZIKV envelope glycoprotein (E protein). This interaction promotes the fusion of viral and endosomal membranes, during which the ZIKV genomic RNAs are released from the endosome into the cytoplasm, a process that facilitates viral replication. However, for DENV2 infection, AP1G1 primarily affects its viral RNA replication stage, rather than the fusion of virus-endosomal membrane. Taken together, our work demonstrates that AP1G1 plays a pro-viral role in both ZIKV and DENV2 infections via distinct mechanisms, highlighting its potential as a therapeutic target for antiviral strategies.

Dengue virus (DENV) remains a pervasive global health threat, further complicated by the occurrence of neutropenia-a distinct clinical feature indicative of an altered host immune response, closely correlated with progressive disease deterioration and increased severity. Nevertheless, the molecular mechanisms underlying dengue-associated neutropenia remain inadequately elucidated. In this study, the comprehensive plasma proteomic profiling of dengue fever (DF) patients, DF patients with neutropenia (DFN), and healthy controls (HC) was systematically analyzed using a deep data-independent acquisition (DIA) workflow combined with LC-MS/MS analysis, to elucidate key cellular pathways and identify promising biomarkers. DFN patients exhibited significant dual hematological alterations, with notable changes in both platelet and neutrophil counts, reflecting a complex disturbance in hematological homeostasis during dengue progression. DIA analysis quantified 2475 proteins, revealing widespread proteomic alterations among the DF, DFN, and HC subjects. Differential analysis highlighted significant fluctuations in proteins related to cytoskeletal organization, metabolic regulation, and intracellular signaling. Enrichment analyses implicated pathways such as focal adhesion, platelet activation, and PI3K-Akt signaling. Machine learning methods further identified a panel of four biomarkers-CNST, DSTN, DUSP3, and PDIA5-with high predictive accuracy for dengue diagnosis and subgroup differentiation. In conclusion, this study advances our understanding of dengue's plasma proteomic landscape and underscores the synergistic potential of DIA-based proteomics and machine learning in unveiling host-response mechanisms, thereby informing early diagnosis and targeted therapeutic strategies.

Swine acute diarrhea syndrome coronavirus (SADS-CoV), an emerging bat-origin Alphacoronavirus with demonstrated zoonotic potential, poses a significant threat to swine health and has considerable economic implications. Currently, no licensed vaccines are available. We constructed a replication-deficient human adenovirus type 5 (Ad5) vectored vaccine candidate, rAd5-SADS-S, which expresses the SADS-CoV spike (S) glycoprotein. The rAd5-SADS-S vaccine elicited robust SADS-CoV-specific humoral immunity and potent cellular responses in both mice and pigs. Notably, rAd5-SADS-S conferred passive protection to neonatal mice against lethal SADS-CoV challenge. These findings establish a preclinical foundation for the development of SADS-CoV vaccines.

High-risk human papillomavirus (HPV) replication requires deregulation of host DNA damage response (DDR) and inflammatory pathways. DNA topoisomerase 2β (Top2β) was previously shown to promote HPV replication. We investigated whether its paralog Top2α protein acts similarly to the virus. Elevated levels of Top2α are consistently observed in cervical intraepithelial lesions and the related carcinomas, as well as in HPV-positive cell lines. Silencing Top2α with shRNA severely suppresses HPV genome maintenance and amplification, but in a DDR-independent manner. Instead, Top2α facilitates secretion of interleukin (IL)-6 and IL-8, which are necessary for HPV replication. Mechanistically, this manipulation is regulated by toll-like receptor 4 (TLR4). Top2α binds to the TLR4 promoter to transcriptionally induce TLR4 expression. Blockade of TLR4 signaling by the specific inhibitor TAK-242 significantly reduces the secreted IL-6/IL-8 levels and HPV replication. Overall, our results reveal a novel role of Top2α to shape the inflammatory microenvironment that benefits HPV replication, making it a promising therapeutic target for HPV-associated diseases.

Protein nanotubes (PNTs) can be regarded as two-dimensional (2D) lattices with p1 or p2 symmetry rolled into tubes. However, attempts to re-assemble their building blocks into stable 2D nanomaterials often fail. Here, starting from two baculoviral capsid proteins, we screened protein variants for the in vitro assembly of various nanotubes and nanosheets. These high-order assemblies were structurally characterized by cryo-electron microscopy techniques. Interfacial analysis of three groups of PNTs revealed that helical heterogeneity is largely the result of the redundancy of p2 symmetry-related contacting interfaces. The assembled nanosheets showed similar interfacial networks to their nanotubular counterparts. In addition, foreign macromolecules could be efficiently displayed on the size-controllable double-layered nanosheets. This study sheds light on the rational design of flexible nanosheets, and it also provides novel 2D protein scaffolds for developing biocompatible materials.