Journal of Virology最新文献

{"title":"Broadly reactive antibodies against influenza B virus hemagglutinin neutralize and protect through distinct structural mechanisms.","authors":"Disha Bhavsar, Alesandro Civljak, Bruno Bonnettaz, Guha Asthagiri Arunkumar, Florian Krammer, Goran Bajic","doi":"10.1128/jvi.00802-26","DOIUrl":"10.1128/jvi.00802-26","url":null,"abstract":"<p><p>Influenza B viruses contribute substantially to seasonal disease burden; however, the structural basis by which antibodies recognize the major glycoprotein hemagglutinin (HA) and mediate antiviral activity remains incompletely defined. Influenza B virus used to circulate as two antigenically distinct lineages, B/Victoria/2/1987-like and B/Yamagata/16/1988-like, although the latter has not been detected in global surveillance in recent years. Antigenic drift in HA contributes to reduced vaccine effectiveness; however, the structural and functional basis by which antibodies recognize influenza B virus HA and mediate antiviral activity remains incompletely defined and thus thwarts our efforts in guiding next-generation vaccine design for broad protection. We characterize four murine monoclonal antibodies (mAb) that broadly bind and neutralize influenza B viruses spanning isolates across four decades of antigenic drift. Using cryo-electron microscopy coupled with <i>in vitro</i> and <i>in vivo</i> functional assays, we show that these antibodies target distinct regions of HA and confer antiviral activity through multiple mechanisms. One antibody engages the receptor-binding site and potently inhibits hemagglutination, whereas others interfere with viral egress and inhibit neuraminidase (NA) activity, suggesting steric occlusion of NA. A medial-junction antibody additionally induces antibody-dependent cellular cytotoxicity <i>in vitro</i>. Despite these mechanistic differences, all antibodies confer complete protection in mice when administered prophylactically or therapeutically. Together, these findings define distinct modes of antibody recognition of influenza B virus HA and link epitope specificity to antiviral function, providing a mechanistic understanding of correlates of immune protection and informing efforts to elicit broadly protective antibody responses against influenza B viruses.IMPORTANCEInfluenza B viruses cause substantial seasonal illness, particularly in children; however, antibody responses against influenza B virus remain less well understood than those against influenza A virus. Here, we identified four antibodies that broadly recognize influenza B virus hemagglutinin and protect through distinct mechanisms. We determined cryo-electron microscopy structures of three antibody-hemagglutinin complexes to define their epitopes and explain their molecular mechanisms of action. One antibody blocks viral attachment by engaging the receptor-binding site, whereas antibodies targeting the medial junction act through post-entry antiviral activity, neuraminidase inhibition, or immune effector functions. Although the antibodies differed in neutralizing potency, all protected mice when administered before infection, and several remained effective after infection. These findings show that broad protection against influenza B virus can arise through multiple antibody targets and mechanisms, informing the evaluation and design of future vac","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0080226"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148892184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interferome profiling in the blood links IFNα5-Mucin-1 axis to HIV-1 pathogenesis.","authors":"Kejun Guo, Stephanie M Dillon, Emily C Meneses, Bradley S Barrett, Alexandra Norman, Kaylee L Mickens, James H Morrison, Ulf Dittmer, Kathrin Sutter, Eric M Poeschla, Katerina Kechris, Cara C Wilson, Mario L Santiago","doi":"10.1128/jvi.01089-26","DOIUrl":"10.1128/jvi.01089-26","url":null,"abstract":"<p><p>Type I interferons (IFN-Is) are essential for antiviral immunity, but contribute to immune dysfunction during chronic HIV-1 infection. IFN-Is comprise multiple IFNα subtypes that signal through a common receptor yet exhibit distinct biological activities, but their qualitative roles in HIV-1 pathogenesis remain incompletely defined. We previously identified IFNα5 as the dominant IFN-I in the systemic circulation of untreated people with HIV (PWH). Here, we delineated IFNα subtype-specific interferomes in peripheral blood mononuclear cells (PBMCs) from HIV-uninfected donors by transcriptomic profiling, and integrated these signatures with blood transcriptomes from untreated PWH, and matched controls. Although the IFN-Is tested induced canonical interferon-stimulated genes (ISGs) <i>in vitro</i>, they also induced different transcriptional programs. <i>In vivo</i>, dysregulation of multiple canonical ISGs, including <i>CD38</i>, <i>LAG3</i>, and <i>CMPK2</i>, correlated with plasma HIV-1 RNA levels, CD4 T-cell depletion, and/or systemic inflammatory markers. By contrast, the IFN-downregulated genes <i>CXCL5</i> and <i>VSIG4</i> were repressed in PWH and inversely correlated with viral load. Notably, <i>MUC1</i>, a non-canonical ISG that was most strongly induced by IFNα5, was significantly upregulated in PWH and associated with the inhibitory receptor <i>LAG3</i>, and markers of IL-6-driven inflammation. Flow cytometric analysis demonstrated increased Mucin-1 surface density on circulating CD4 T cells of PWH vs controls. Together, these findings demonstrate that IFNα subtypes can drive qualitatively distinct responses in bulk PBMC, identify IFNα5-associated gene programs in blood that may contribute to immune dysregulation among untreated PWH, and refine current models of IFN-I involvement in HIV-1 pathogenesis.IMPORTANCEPeople living with HIV experience persistent immune activation and inflammation that contribute to immune system damage and long-term health complications. Molecules known as type I interferons (IFN-Is) help control viruses early in infection, but prolonged exposure to these signals may also worsen immune dysfunction. Here, we show that IFNα5 is the dominant interferon present in the blood of people with untreated HIV and activates a distinct gene program in circulating immune cells. This program includes genes linked to immune activation, metabolic dysfunction, and immune exhaustion. IFNα5 strongly induces Mucin-1 on CD4 T cells, which is associated with systemic inflammation. These findings identify IFN pathways that may contribute to immune dysfunction during chronic HIV infection and highlight potential targets for restoring immune health.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0108926"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The α-helix-facilitating amino acid sequence EAAAK dramatically increases the antiviral activity of SARS-CoV-2 fusion-inhibitory peptides via the endosome fusion pathway.","authors":"Zhixin Yao, Yuanmei Zhu, Nian Liu, Yue Hu, Yuxian He","doi":"10.1128/jvi.01067-26","DOIUrl":"10.1128/jvi.01067-26","url":null,"abstract":"<p><p>The SARS-CoV-2 fusion-inhibitory lipopeptide IPB29 features a unique design incorporating the α-helix-promoting EAAAK sequence as a rigid linker between the peptide backbone and the conjugated lipid, exhibiting greatly improved antiviral activity compared to lipopeptides with conventional flexible linkers. Here, we characterized its mechanism of action and uncovered several critical insights. First, IPB29 remained the most potent inhibitor of emerging Omicron subvariants compared to IPB24 and IPB28, which share the same peptide sequence but employ flexible polyethylene glycol or glycine-serine repeat linker. Notably, this enhanced potency was abolished in Vero E6 cells stably expressing TMPRSS2, where viral entry occurs via the plasma membrane fusion pathway. Visualization using FITC-labeled lipopeptides demonstrated that IPB29 binds to and enters target cells more efficiently. Subsequently, we generated two unconjugated template peptides, P43 (containing EAAAK) and P37 (lacking EAAAK). P43 exhibited superior inhibitory activity compared to P37 in Huh-7 and 293T/ACE2 cells, but not in Vero E6-TMPRSS2 cells. Both peptides showed comparable efficacy in blocking S protein-driven cell-cell fusion. Although P43 displayed enhanced α-helicity relative to P37, both peptides exhibited similar target-binding affinities. Instead, the cellular uptake of P43 was markedly more efficient, further supporting that the improved antiviral effect is attributable to the inhibition of the viral endosomal fusion pathway. Collectively, our studies provide molecular insights into the antiviral mechanism of IPB29 and propose the short EAAAK sequence as a generalizable strategy for enhancing the efficacy of peptide-based therapeutics.</p><p><strong>Importance: </strong>The development of effective therapeutics against SARS-CoV-2 remains an urgent priority. IPB29, a potent broad-spectrum lipopeptide fusion inhibitor currently in clinical trials, requires mechanistic elucidation. Here, we demonstrate that the C-terminal EAAAK motif in IPB29-originally designed as a rigid linker connecting the peptide backbone to the lipid moiety-is critical for its antiviral activity and functions via the endosomal fusion pathway. These findings reveal a generalizable strategy for optimizing antiviral drug design.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0106726"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights into the mechanism of action of the bipartite fusion module of SARS-CoV-2 spike protein.","authors":"Carolina C Buga, Mariana Valério, Marta Alenquer, Marta Pires de Miranda, Manuel N Melo, Miguel A R B Castanho, Maria João Amorim, Cláudio M Soares, João B Vicente, Ana Salomé Veiga, Diana Lousa","doi":"10.1128/jvi.00688-26","DOIUrl":"10.1128/jvi.00688-26","url":null,"abstract":"<p><p>SARS-CoV-2 entry into host cells is mediated by the spike glycoprotein, which promotes fusion between viral and host membranes. Despite its importance, the precise location and mode of action of the fusion peptide, a key spike region that inserts into and perturbs the host membrane, remain elusive. Two regions have been proposed as fusion peptides: one located at the N-terminus of the protein (nFP) and the other at an internal position (iFP). Here, we combine computational and experimental approaches to characterize their roles and impact on membrane fusion. Molecular dynamics (MD) simulations indicated that the nFP interacts mostly at the membrane surface. Consistently, experimental biophysical assays revealed that the nFP exhibits low affinity and weak perturbing effects on lipid vesicles. In contrast, the iFP exhibits stronger membrane binding and induces stronger perturbation <i>in vitro</i>. MD simulations show that the iFP inserts deeply into and strongly affects the membrane, inducing lipid tail protrusion and increased water flux through the bilayer. Moreover, spike-pseudotyped lentiviruses carrying mutations in the iFP region showed that residues Y873, F888, and F906 are required for viral entry. Together, our findings suggest that SARS-CoV-2 uses a bipartite fusion module in which the nFP establishes initial contact with the host membrane and primes the bilayer, enabling subsequent deep insertion and further membrane destabilization promoted by the iFP. Given that FPs are conserved across viral families, a similar fusion module may be present in other coronaviruses, making this region a promising target for the development of broad-range antiviral therapeutics.</p><p><strong>Importance: </strong>We studied how SARS-CoV-2 enters human cells by focusing on a key region of its spike protein, known as the fusion peptide, which interacts with the host membrane. Although this region is essential for infection, its exact location and mechanism of action have remained unclear, with two candidate regions proposed. Using a combination of computational and experimental approaches, we found that these regions act together through a bipartite fusion module. One region initiates contact with the membrane, while the other inserts more deeply and drives the membrane perturbations required for viral entry. Given the relevance of this peptide for viral entry, these insights are expected to guide the development of novel antiviral therapies.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0068826"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148968933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New form of HPV18 L1 found in native virions contributes to virion stability and infectivity.","authors":"Eric J Ryndock, Jennifer Biryukov, Kumari Asha, Sarah Brendle, Neil D Christensen, Craig Meyers","doi":"10.1128/jvi.00167-26","DOIUrl":"10.1128/jvi.00167-26","url":null,"abstract":"<p><p>Current dogma states that papillomavirus virions consist of only one form of the L1 major capsid protein. Human papillomaviruses (HPVs) have been studied using recombinant particles, thereby bypassing the need to grow the virus in a model of differentiating epithelium. Expression vectors engineered to produce L1 utilize a consensus methionine found in many HPV types. However, HPV18 has two additional in-frame methionine residues located 61 and 26 amino acids upstream of the consensus methionine. These methionine residues are excluded from the L1 expression vector used to create the recombinant virus. On the other hand, HPV produced from organotypic raft culture allows virions to be assembled in a differentiating epithelium in the presence of its native promoters and complete genome. Here, we have utilized this system to show that the wild-type HPV18, produced in a more natural setting, translates a larger form of L1 from the upstream methionine, which is 61 amino acid residues upstream from the consensus methionine, and a smaller form from the consensus methionine, with both sizes assembled in the newly formed virion. Ablation of the upstream methionine residue at position 61 altered the virion capsid conformation, and also decreased virion stability and infectivity.</p><p><strong>Importance: </strong>The present study investigates whether the papillomavirus virions contain more than one isoform of the L1 major capsid protein. By using organotypic raft cultures that mimic the naturally differentiating epithelium, we revealed that wild-type HPV18 expresses and incorporates two distinct L1 isoforms into the virion, including a previously unrecognized longer form translated from an upstream methionine. Our study has further shown that disruption of the upstream methionine impairs virion stability and infectivity, demonstrating that the longer L1 isoform contributes to proper capsid architecture and viral function. These findings offer a new understanding of HPV capsid biology and have significant implications for the future development of HPV vaccines, diagnostics, and antiviral therapies.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0016726"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148944671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CRISPR and yeast two-hybrid screens identify CD81 as a proviral host factor for PRRSV.","authors":"Yongjie Chen, Zhan He, Yanfei Pan, Yunyan Luo, Baoying Huang, Yi Zhang, Guohao Li, Chunhe Guo","doi":"10.1128/jvi.01033-26","DOIUrl":"10.1128/jvi.01033-26","url":null,"abstract":"<p><p>Porcine reproductive and respiratory syndrome virus (PRRSV) remains a major economic burden on the global swine industry. Identifying host factors that mediate viral invasion is critical for developing antiviral strategies. Here, using a CRISPR screen targeting genes encoding cell surface CD proteins combined with yeast two-hybrid screening, we identified the tetraspanin CD81 as a novel host factor that promoted PRRSV infection by directly interacting with viral glycoprotein 5 (GP5). CD81 knockdown reduced PRRSV infection, whereas CD81 overexpression enhanced it. Consistently, antibody-mediated blockade of CD81 restricted infection in both Marc-145 cells and primary porcine alveolar macrophages. Mechanistic analysis showed that CD81 mainly facilitated viral internalization, and its C-terminal transmembrane region was required for GP5 binding and efficient infection. During infection, CD81 underwent autophagic degradation mediated by the selective autophagy receptor NDP52, suggesting a host restriction response that reduced CD81 availability. PRRSV countered this process by promoting NDP52 degradation, thereby stabilizing CD81 and favoring infection. These findings identify CD81 as both a key factor in PRRSV pathogenesis and a potential target for antiviral intervention.IMPORTANCEPorcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most economically important swine pathogens worldwide, yet effective antiviral strategies are lacking because of its extensive genetic diversity and immune evasion. Here, we identified the tetraspanin CD81 as a previously unrecognized host factor that promoted efficient PRRSV infection. CD81 directly interacted with the viral glycoprotein GP5 to facilitate viral internalization, whereas disruption of CD81 by genetic depletion or antibody blockade markedly restricted infection. We further demonstrated that CD81 abundance was controlled by NDP52-mediated selective autophagy as an intrinsic antiviral mechanism, which PRRSV overcame by degrading NDP52 to stabilize CD81 and enhance viral replication. These findings reveal a previously unrecognized virus-host interaction that governs PRRSV entry and identify CD81 as a promising host-directed therapeutic target.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0103326"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148963549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative fitness of reemerging St. Louis encephalitis virus in vertebrate and mosquito cells, <i>Culex tarsalis</i> and <i>Culex quinquefasciatus</i> mosquitoes, and mice.","authors":"M Arturo Flores Rodriguez, Hongwei Liu, Erik Turner, Elias Im, Rochelle Leung, Sunny An, Christopher M Barker, Lark L Coffey","doi":"10.1128/jvi.00952-26","DOIUrl":"10.1128/jvi.00952-26","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The human pathogenic orthoflavivirus St. Louis encephalitis virus (SLEV) reemerged in the western United States in 2015 after more than a decade of absence and has since expanded throughout California with sustained interannual transmission. This shift from the historically sporadic pattern of SLEV activity before 2003 raises the question of whether contemporary strains differ in fitness from earlier strains. To assess whether reemerging SLEV possesses enhanced infectivity or transmissibility, we compared five contemporary genotype III strains from California (2016-2023) with a historical genotype V strain from 2003. Growth kinetics were evaluated in mammalian, duck, and mosquito cells; vector competence was assessed in laboratory colonies of &lt;i&gt;Culex tarsalis&lt;/i&gt; and &lt;i&gt;Culex quinquefasciatus&lt;/i&gt; vectors; and SLEV RNA levels in blood were measured in collaborative cross recombinant intercross mice. Some genotype III strains produced higher titers than the historical genotype V strain in avian, but not mammalian or mosquito cells. Several genotype III strains infected and transmitted SLEV RNA more efficiently than the historical strain in both mosquito species, although no temporal trend in fitness was observed. SLEV fitness was comparable or greater in &lt;i&gt;Culex quinquefasciatus&lt;/i&gt; than in &lt;i&gt;Culex tarsalis&lt;/i&gt;. Sequencing identified no shared amino acid substitutions associated with vector infection phenotypes. Although genotype III strains exhibited a delayed peak relative to the historical strain, murine SLEV RNA levels in blood were comparable across strains. These findings show some contemporary strains exhibit equal or greater fitness than the historical strain, which may contribute to SLEV persistence and spread in California, underscoring the need for continued surveillance and targeted vector control.IMPORTANCESt. Louis encephalitis virus (SLEV) reemerged in California in 2015 after more than a decade of absence and has since established sustained transmission and expanded geographically. The factors underlying this reemergence remain poorly understood. By comparing contemporary genotype III SLEV strains with a historical genotype V strain, we found that several contemporary strains exhibit equal or greater fitness compared to the historical strain in avian cells and are transmitted more efficiently by the two principal California vector species, &lt;i&gt;Culex tarsalis&lt;/i&gt; and &lt;i&gt;Culex quinquefasciatus&lt;/i&gt;. We also demonstrate that &lt;i&gt;Cx. quinquefasciatus&lt;/i&gt; can transmit infectious genotype III SLEV, supporting its role in SLEV maintenance and spread. Despite differences in mosquito infection and transmission, we found no evidence that fitness in mosquito vectors or mice has continued to rise among strains detected more recently, suggesting that enhanced transmission is not driven by ongoing directional adaptation in these models. These findings indicate that contemporary genotype III SLEV strains possess transmission competence in mo","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0095226"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generation and characterization of a PRRSV-2 DIVA marker virus by deletion of a novel epitope in the nucleocapsid protein.","authors":"Jiwen Sun, Jian Wang, Kun Li, Delong Wei, Jiaoyang Li, Pu Sun, Dong Li, Pinghua Li, Yimei Cao, Lijie Tang, Zengjun Lu, Jing Zhang","doi":"10.1128/jvi.01259-26","DOIUrl":"10.1128/jvi.01259-26","url":null,"abstract":"<p><p>Porcine reproductive and respiratory syndrome virus (PRRSV) infection causes enormous economic losses to the world pig industry. Currently, there is no DIVA (differentiating infected from vaccinated animals) vaccine for PRRS available on the market. In this study, we successfully produced a porcine monoclonal antibody (C8) against PRRSV nucleocapsid (N) protein using fluorescence-based single-B-cell antibody technology. The C8 monoclonal antibody (mAb) recognizes a novel linear epitope (₉₂LSDSGRISYTVE₁₀₃) at the C terminus of genotype 2 PRRSV N protein. We developed a competitive enzyme-linked immunosorbent assay for detecting PRRSV N protein antibodies against this epitope using C8 mAb. Furthermore, we successfully rescued one PRRSV mutant, rGSWW15/N∆93. <i>In vitro</i> and <i>in vivo</i> assays showed that the mutant virus replicated efficiently and elicited a specific antibody response to PRRSV as measured by a commercial ELISA, but not to the specific epitope (₉₂LSDSGRISYTVE₁₀₃) detected by our competitive ELISA (cELISA). Our findings suggest that the recombinant virus, in combination with the cELISA diagnostic tests, enables serological differentiation between animals vaccinated with the marker virus and those infected with the wild-type virus. This study demonstrates the feasibility of developing a PRRSV DIVA vaccine through targeted modification of an N protein epitope, providing a potential strategy to facilitate PRRS control.</p><p><strong>Importance: </strong>The development of a PRRSV DIVA vaccine is crucial for effectively managing outbreaks in swine populations. DIVA vaccines allow differentiation between vaccinated and naturally infected animals, aiding disease surveillance. In this study, we identified a novel linear epitope (92LSDSGRISYTVE103) on the genotype 2 PRRSV N protein and developed the porcine monoclonal antibody C8 targeting this epitope. A competitive ELISA (cELISA) was then created to detect PRRSV N protein antibodies specific to the C8 epitope. Additionally, we successfully generated an epitope deletion mutant, rGSWW15/N∆93. While <i>in vivo</i> assessments confirmed specific antibody responses via commercial ELISA, these antibodies did not recognize the C8-specific epitope identified in our cELISA. These findings suggest that combining the recombinant virus with cELISA diagnostic tests allows accurate differentiation between vaccinated and wild-type virus-infected animals.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0125926"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Co-administration of intranasal parainfluenza virus vaccines expressing antigenically distinct SARS-CoV-2 S antigens elicits broad and durable immunity in hamsters.","authors":"Hong-Su Park, Yumiko Matsuoka, Celia Santos, Eleanor F Duncan, Jaclyn A Kaiser, Lijuan Yang, Cindy Luongo, Xueqiao Liu, I-Ting Teng, Peter D Kwong, Ursula J Buchholz, Cyril Le Nouën","doi":"10.1128/jvi.00938-26","DOIUrl":"10.1128/jvi.00938-26","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Intranasal COVID-19 vaccines with the ability to induce broad and durable mucosal and systemic immunity would be useful as stand-alone vaccines or in combination with injectable vaccines. We evaluated in hamsters the breadth of immunity and durability of protection elicited by co-administration of two live-attenuated bovine/human parainfluenza virus type 3 (B/HPIV3) vectors expressing antigenically distinct prefusion-stabilized S proteins of the ancestral SARS-CoV-2 isolate (B/HPIV3/S-6P) or the BA.5/Omicron variant (B/HPIV3/S-BA.5-2P). These vectors are being developed as bivalent pediatric vaccines against HPIV3 and SARS-CoV-2 and are based on bovine PIV3 with the fusion (F) and hemagglutinin-neuraminidase (HN) glycoproteins replaced by those of human PIV3. To broaden the S-specific antibody response, we evaluated co-administration of these B/HPIV3 S-expressing vectors. Each B/HPIV3 S-expressing vector induced robust serum anti-S IgG and IgA antibody levels to the antigen-matched S protein that were sustained for at least 5 months. Co-administration increased the breadth of the S-specific antibody response, spanning the breadth of the response elicited by each vector individually. Hamsters immunized intranasally with the mixture of vectors developed neutralizing antibodies to ancestral and recently circulating SARS-CoV-2 strains and were protected against BA.5/Omicron challenge 5 months after immunization, with no weight loss, SARS-CoV-2 challenge virus replication, or increase in host inflammatory cytokines in the airways after the challenge, indicating durable protection. Thus, intranasal co-administration of live-attenuated B/HPIV3 expressing antigenically distinct S proteins induced broad and durable antibody responses, and long-term protection against BA.5/Omicron challenge. This approach warrants further development and may better protect against emerging SARS-CoV-2 variants.IMPORTANCEIntranasal SARS-CoV-2 vaccines that induce systemic and local mucosal immunity hold promise, especially as booster vaccines against SARS-CoV-2 variants. We developed live-attenuated bovine/human parainfluenza virus type 3 (B/HPIV3)-vectored vaccines as bivalent pediatric vaccines against PIV3 and SARS-CoV-2. Co-administration in a single dose of two B/HPIV3 vectors, one expressing the spike protein S from the ancestral Wuhan-Hu-1 strain and one expressing S of BA.5/Omicron, induced broad serum anti-S antibody responses that remained strong for at least 5 months. Hamsters challenged with the BA.5/Omicron strain 5 months after immunization were protected from weight loss, inflammatory responses, and challenge virus replication in the airways. Thus, in the hamster model, intranasal co-administration of live-attenuated B/HPIV3 expressing SARS-CoV-2 S elicits protection durable over several months, and combining two antigenically distinct B/HPIV3 S-expressing vectors substantially broadens the antibody response. This mucosal immunization approach may provid","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0093826"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional redundancy, complementation, and cross-talk between CH25h and IFITM3 in infection and in IFITM3 trafficking and secretion.","authors":"Yuxin Song, Tingting Xia, Charlène Martin, Gaetan Despres, Julien Burlaud-Gaillard, Antonin Lamaziere, Philippe Roingeard, Andrea Cimarelli","doi":"10.1128/jvi.01378-26","DOIUrl":"10.1128/jvi.01378-26","url":null,"abstract":"<p><p>Type I interferon induces multiple protein effectors to inhibit viral replication. Among these, the interferon-induced transmembrane protein (IFITM3) and the cholesterol-25-hydroxylase (CH25h) converge on the inhibition of viral entry by altering the behavior of membranes. Here, we dissect the functional and mechanistic relationship between these two membrane-acting effectors using different viruses. When using HIV-1 and vesicular stomatitis virus (VSV), IFITM3 and CH25h restrict viral entry with similar efficiency but act in a largely redundant manner, a finding that is consistent across infection systems, cell types, and entry assays. However, this is not the case for several orthoflaviviruses against which IFITM3, but not CH25h, provides a strong block to infection. We further uncover that the CH25h-25HC axis remodels IFITM3 trafficking by driving partial relocalization of IFITM3 from endolysosomal compartments to the plasma membrane. This occurs by impairing IFITM3 internalization into early endosomes and leads to an increase in its secretion in exosomal vesicles, overall indicating that CH25h contributes to regulate IFITM3 cellular dynamics. Together, these findings reveal that the apparent redundancy of maintaining two distinct effectors targeting the same step of the viral life cycle is not superfluous but instead allows the cell to compensate and, nonetheless, target viruses that may have developed resistance to one of these effectors. Furthermore, the ability of CH25h to remodel IFITM3 trafficking indicates that these two pathways are connected, adding an additional layer of complexity in the biology of IFITM3.IMPORTANCEIFITM3 and CH25h are two potent, broad-acting inhibitors of viral membrane fusion, but their functional connections have not been explored. Here, we show that although their antiviral activities are largely redundant against HIV-1 and vesicular stomatitis virus (VSV), IFITM3 functionally compensates for a relative resistance of orthoflaviviruses toward CH25h. Furthermore, CH25h redistributes IFITM3 from endosomal compartments to the plasma membrane, enhancing its release in exosomal vesicles. Overall, these findings reveal that despite the fact that IFITM3 and CH25h can act redundantly against certain classes of viruses, IFITM3 can functionally compensate for CH25h resistance against other viruses, highlighting why it is important for the cell to maintain two distinct pathways to block virus-to-cell membrane fusion. In addition, these results also reveal how interferon-driven lipid remodeling can reshape the trafficking behavior of IFITM3, leading it to be more present in exosomes, where it could exert paracrine functions that remain to be explored.</p>","PeriodicalId":17583,"journal":{"name":"Journal of Virology","volume":" ","pages":"e0137826"},"PeriodicalIF":4.1,"publicationDate":"2026-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149069833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}