Journal of Virology最新文献

HIV-1 continues to pose a significant global health challenge, requiring ongoing research into effective prevention and treatment strategies. Understanding the B-cell repertoire that can be engaged upon vaccination in humans is crucial for the development of future preventive vaccines. In this study, peripheral blood mononuclear cells from HIV-negative participants in the multivalent HVTN124 human HIV-1 vaccine clinical trial were interrogated for HIV-reactive B cells using LIBRA-seq, a high-throughput B-cell mapping technology. We report the discovery of glycan-reactive antibodies, with one of these being capable of neutralizing diverse heterologous HIV-1 virus strains. Furthermore, isolated antibodies showed broad cross-reactivity against antigens from a variety of other pathogens. The emerging class of glycan-reactive virus-neutralizing antibodies with exceptional breadth of pathogen cross-reactivity may present an effective target for vaccination at the population level.

Importance: Understanding how the human immune system recognizes and combats viruses is crucial for developing better vaccines and treatments. Here, through characterization of the B-cell receptor repertoires of participants in HVTN124, a multivalent HIV-1 vaccine human clinical trial, we discovered antibodies that recognize sugar molecules (glycans) on antigens from a range of unrelated viral families. In addition to their binding breadth, these antibodies can also neutralize multiple diverse strains of HIV-1. Our findings reveal an emerging and underappreciated mechanism for antibodies to counteract virus infection, potentially opening doors for developing vaccines that preferentially elicit glycan-reactive antibody species to broadly protect against different viruses.This study is registered with ClinicalTrials.gov as NCT03409276.

A paucity of reports is available describing the structures of Shigella phages, and these have focused to date on a few short, non-contractile podophages and one long contractile myophage. Here, we report the cryo-EM structure of a Shigella siphophage, where we can visualize the capsid and surface decoration proteins and many components of the tail, including the Tail Tube Protein (TTP), Distal Tail Protein (DTP), Baseplate Hub Proteins (BHUB1 & BHUB2), and the Tape Measure Protein (TMP). The tail is also decorated with six copies of a trimeric tailspike protein that is similar to Sf6-like and P22-like phages. We used mass spectrometry to confirm the identity of the proteins in the mature virion and present atomic models for the majority of these phage proteins. In addition, host range studies show clearly that these tailspike appendages have a homologous function to those in the Sf6-like and P22-like phages in recognizing the O-antigen on the host lipopolysaccharide (LPS).IMPORTANCEFew Shigella phages have been studied structurally to date. By characterizing phage Sf11, we see evidence for a tail adaptor domain that is used for decorating the siphophage tail tip with enzymatic, P22-like tailspike proteins. This is important for both understanding the evolutionary relationships among Shigella phages and also could be exploited as a type of protein scaffolding for creating designer phages for therapeutic and/or industrial purposes.

Influenza continues to pose a serious threat to humans. Influenza-host interaction is incompletely understood, requiring identification of host factors that regulate viral pathogenicity. Ceramide synthases (CerSs) are responsible for producing and controlling ceramide levels within cells. Ceramides are structural and signaling sphingolipid components that mediate various biological functions and affect the infectivity of multiple viruses. However, the role of CerSs during virus infections remains unclear. In this study, we investigated the possible function of CerSs in host defense against influenza virus infection. Cells stably expressing CerS4 poorly supported influenza virus replication, whereas CerS1 did not affect replication. Transient overexpression of CerS4 also impaired the efficient production of viral proteins as well as infectious progeny viruses. In support of these results, knockdown of endogenous CerS4 in cells enhanced virus replication. Intriguingly, CerS4 impeded virus-induced activation of cellular c-Jun N-terminal kinase (JNK), which interfered with influenza viral replication. On the other hand, influenza virus infection was shown to induce CerS4 ubiquitination and downregulation, which could limit the antiviral activity of CerS4. Collectively, these findings reveal a new function of CerS4 that restricts influenza virus infection and provides valuable insights into influenza-host defense interactions.IMPORTANCESeasonal influenza causes serious public health problems in the world with substantial annual morbidity and mortality. Further, there have been persistent concerns about potential development of an influenza pandemic. Current antiviral drugs are limited in their efficacy, especially due to the rapid emergence of drug-resistant variants. Host protein-directed therapy is an alternative or complementary approach to broadly controlling influenza virus infections but requires a deeper understanding of influenza-host interplay. Host ceramide synthase 4 regulates the level of ceramides that possess both structural and signaling mediator functions. Our study reveals that ceramide synthase 4 displays an antiviral activity against influenza virus infection by regulating JNK activation. However, influenza virus triggers degradation of ceramide synthase 4, which could favor virus replication. The findings advance our knowledge about the ceramide network interaction with influenza and provide a framework for developing a host-targeted therapy to cure influenza.

ANKLE2 (Ankyrin repeat and LEM domain-containing protein 2) is an emerging host factor with previously undefined roles in antiviral defense. Here, we show that ANKLE2 can exert robust antiviral activity against vaccinia virus by regulating the phosphorylation status of barrier-to-autointegration factor (BAF), a ubiquitous DNA-binding protein that compacts DNA and restricts viral replication. We first demonstrate that depletion of endogenous ANKLE2 increased BAF phosphorylation and rescued replication of B1-knockout vaccinia virus, whereas reconstitution restored restriction. We then perform domain-mapping experiments of ANKLE2, revealing that its LEM domain and Caulimovirus domain (CD domain) are essential for BAF dephosphorylation, ANKLE2-BAF association, and/or antipoxviral activity, whereas the transmembrane (TM) domain restricts cytoplasmic redistribution and functions as a negative regulator. Together, these findings uncover a previously unrecognized host defense pathway against poxviruses, provide new insight into how host ANKLE2 proteins coordinate antiviral responses, and reveal a novel antiviral role for ANKLE2 in limiting vaccinia virus DNA replication and progeny release through regulation of BAF phosphorylation.IMPORTANCEVaccinia virus relies on disabling host defenses to replicate efficiently, with the host DNA-binding protein BAF representing a key target for viral kinases. Here, we uncover ANKLE2 as a critical host factor that counteracts vaccinia virus by sustaining the antiviral activity of BAF. ANKLE2 promotes BAF dephosphorylation, thereby preventing viral escape from BAF-mediated restriction. Our results reveal that distinct domains of ANKLE2 differentially regulate its antiviral activity, with the LEM and CD domains promoting BAF dephosphorylation and antiviral activity, and the transmembrane domain acting as a negative regulator by limiting cytoplasmic redistribution. These findings highlight ANKLE2 as a domain-dependent regulator of host defense and expand our understanding of the molecular circuitry that controls poxvirus replication.

The Crimean-Congo hemorrhagic fever orthonairovirus (CCHFV) is a widespread tick-borne agent that causes severe disease in humans. Its expanding geographic range poses a significant public health threat. Although animal models for CCHFV infection have been developed, the requirement for maximum biosafety level 4 facilities limits the development of countermeasures against the virus. Hazara virus (HAZV) is a closely related orthonairovirus that can be handled in biosafety level 2 containment and has been proposed as a prototype virus for the Orthonairovirus genus to facilitate early-stage countermeasure development against the highly pathogenic CCHFV. Here, we present a detailed characterization of HAZV infection in mice deficient in type I interferon signaling (Ifnar^-/-), providing insights into the natural history of orthonairovirus disease and highlighting similarities and differences between the HAZV and previously described CCHFV mouse infection models. We then utilized the HAZV mouse infection model to test the efficacy of a promising broad-spectrum antiviral, 4'-fluorouridine (4'-FlU). Our findings demonstrate that delayed intervention with orally administered 4'-FlU can rescue clinically ill mice following challenge with a lethal dose of HAZV, supporting further investigations of the compound's efficacy in CCHF disease models.

Importance: The Crimean-Congo hemorrhagic fever orthonairovirus poses a significant public health threat, underscored by the expansion of Hyalomma genus tick vectors and the lack of clinically proven therapeutic options. The related Hazara orthonairovirus (HAZV), which has not been reported to cause human disease, has been proposed as a prototype virus for the Nairoviridae family. Here, we characterize in detail the mouse model of lethal HAZV disease to gain further insight into nairovirus pathogenesis and use the model for the preclinical development of a promising broad-spectrum antiviral drug candidate, 4'-fluorouridine (4'-FlU). Our findings highlight the value of HAZV as a surrogate for proof-of-concept studies supporting early-stage antiviral drug studies and the therapeutic potential of 4'-FlU for the treatment of often-fatal Crimean-Congo hemorrhagic fever.

Ubiquitination plays critical roles in viral infections. This study demonstrates that porcine reproductive and respiratory syndrome virus (PRRSV) endoribonuclease nsp11 undergoes K48-linked polyubiquitination specifically at the conserved catalytic residue lysine 173 (K173) during viral infection. This modification targets nsp11 for degradation via the ubiquitin-proteasome system (UPS), as evidenced by the profound stabilization of a ubiquitination-deficient K173R mutant. Remarkably, this ubiquitination mechanism targeting the endonuclease active site is evolutionarily conserved across most arteriviruses, including simian hemorrhagic fever virus and equine arteritis virus, with mouse lactate dehydrogenase-elevating virus being an exception. We further identify the host E3 ubiquitin ligase TRIM29 as a key regulator that binds PRRSV nsp11 via its coiled-coil domain and specifically promotes its K48-linked ubiquitination and subsequent proteasomal degradation. TRIM29-mediated degradation of nsp11 counteracts nsp11's suppression of interferon (IFN-β) and interferon-stimulated gene production. Consequently, TRIM29 significantly inhibits PRRSV replication. Collectively, these findings uncover a conserved UPS-mediated regulatory mechanism targeting a critical arteriviral endonuclease and demonstrate TRIM29 as a potent host restriction factor that antagonizes PRRSV immune evasion by degrading nsp11.IMPORTANCEThis study reveals that porcine reproductive and respiratory syndrome virus (PRRSV) nsp11 undergoes K48-linked polyubiquitination at catalytic residue K173, triggering ubiquitin-proteasome system (UPS)-mediated degradation, a mechanism conserved in most arteriviruses. The host E3 ligase TRIM29 binds nsp11 via its coiled-coil domain, catalyzing this ubiquitination to degrade nsp11. This counteracts nsp11's suppression of interferon (IFN-β)/interferon-stimulated gene production and inhibits PRRSV replication. These findings identify TRIM29 as a key host restriction factor that disrupts viral immune evasion by targeting a conserved arteriviral endonuclease via the UPS.

Mycoviruses possess a potential role for biological control due to their ability to reduce both virulence and vegetative growth in some phytopathogenic fungi. However, mycoviruses that enhance fungal pathogenicity have been poorly studied and characterized. In this study, a novel double-stranded RNA (dsRNA) fungal virus, tentatively named Sinodiscula camellicola partitivirus 1 (ScPV1), was identified in the phytopathogenic fungus Sinodiscula camellicola, isolated from tea leaves. ScPV1 possesses two genomic components of 1,835 bp and 1,697 bp in length, each containing an open reading frame (ORF) encoding a putative RNA-dependent RNA polymerase (RdRP) and coat protein (CP), respectively, as confirmed by mass spectrometry. Phylogenetic analysis of the amino acid sequences of the RdRPs from ScPV1 and related mycoviruses placed ScPV1 within a newly proposed genus, Epsilonpartitivirus, in the family Partitiviridae. The virus was purified using ultracentrifugation, and transmission electron microscopy revealed that ScPV1 dsRNA genomes are encapsidated in virus particles ca. 31 nm in size, ranging from 24.9 to 36.8 nm, together with the RdRP protein, which was of an unexpected size. Transfection with purified virions generated transfectants with significantly reduced growth rates but with increased virulence, indicating that ScPV1 confers unusual effects on its host fungus. This finding represents a significant advancement in understanding the complex interactions between mycoviruses and their host fungi.

Importance: Here, we identified a novel partitivirus, tentatively named Sinodiscula camellicola partitivirus 1 (ScPV1), marking the first report of a partitivirus from a phytopathogenic fungus infecting tea plants. ScPV1 is characterized by possession of two dsRNA genomic components encapsidated in particles of varying sizes, along with an RNA-dependent RNA polymerase protein of an expected size, which contained some unique amino acids, indicating its distinct molecular and morphological traits. Biological tests on transfectants generated following protoplast infection with purified virions demonstrated that ScPV1 impairs vegetative growth while enhancing virulence in its fungal host. This finding represents the first instance of a mycovirus responsible for hypervirulence on a phytopathogenic fungus through virion transfection, as well as the first case of a partitivirus conferring hypervirulence while reducing vegetative growth in a phytopathogenic fungus. We anticipate that these findings will significantly advance our understanding of the complex interactions between mycoviruses and their host fungi.

Passive administration of broadly neutralizing anti-influenza monoclonal antibodies (mAbs) before or after virus infection can prevent or alleviate disease. Unlike seasonal influenza, infection with zoonotic avian influenza viruses can lead to acute respiratory distress syndrome and high mortality in humans. Respiratory tract-targeting antibody delivery appears to be more clinically relevant and effective for zoonotic influenza treatment. In this study, the efficacy of an anti-H7N9 murine mAb 4B7 and its humanized form (chi4B7) against H7 subtype influenza viruses administered through the intranasal route was investigated in mice. 4B7 recognizes critical residues in the vestigial esterase domain and receptor-binding sites in the hemagglutinin of H7N9 virus. The antibody had cross-H7 binding, hemagglutination inhibition, and neutralizing activities. In particular, the dose of 4B7 required for prophylactic protection against H7N9 infection was significantly reduced in mice treated locally (intranasal) compared with those treated systemically (intraperitoneal). Intranasal delivery of the antibody also enhanced therapeutic efficacy against H7N9 infection compared to intraperitoneal administration. Chi4B7 generated by grafting the variable regions onto the human IgG1 backbone sustained cross-reactivity with different H7 viruses of the parental murine antibody. Airway-delivered chi4B7 provided broad prophylactic and therapeutic protection against divergent H7 viruses in mice. Moreover, intranasal administration of chi4B7 had a long effective prophylaxis window against H7N9 infection. Our results suggest that airway delivery of the humanized anti-H7 antibody is a favorable approach for broad-spectrum prophylaxis and therapy against the H7 subtype influenza.IMPORTANCEInfection of zoonotic H7 avian influenza viruses can cause severe respiratory symptoms and high mortality in humans. Monoclonal antibody administration is an effective approach for treatment of zoonotic influenza infection, while systematic routes of antibody administration (typically intravenous infusion) have several shortcomings. However, there are no approved anti-H7 antibody therapies, and the efficacy of antibodies administered through the airway route against H7 viruses has not been fully investigated. Herein, we report a murine broadly neutralizing monoclonal antibody against divergent H7 viruses and reveal that intranasal administration enhanced prophylactic and therapeutic efficacy of this antibody against H7N9 virus compared to systemic administration. Airway delivery of the humanized antibody conferred broad protection against diverse strains of H7 virus in mice. Our study presents new candidates of broad antiviral agents against H7 avian influenza viruses and highlights airway delivery as a more potent manner of administering antibodies for clinical treatment of influenza.

Respiratory syncytial virus (RSV) is the leading cause of respiratory infection-related hospitalizations in children younger than 5 years. Neutralizing nanobody-based interventions represent a promising strategy against RSV. Here, we identify a novel nanobody (4-H1) targeting the RSV prefusion F (pre-F) protein, which demonstrates potent neutralization against both RSV A and B subtypes. Epitope characterization via binning assays, molecular docking, and mutational analyses revealed that 4-H1 interacts with a unique region within antigenic site Ø by engaging critical residues L207, K209, and the K65-N67-C69 cluster. To improve the in vivo efficacy and stability of the 4-H1 nanobody, we engineered a heterotrimeric bispecific nanobody (4-H1-anti-HSA-4-H1). This single-chain molecule contains two anti-RSV F nanobody domains and one anti-human serum albumin (HSA) domain, resulting in a trivalent molecule with dual specificity. This construct demonstrated sub-nanogram per milliliter (sub-ng/mL) neutralization potency against both RSV A and B subtypes, with prolonged in vivo half-life. Notably, intranasal administration of this construct before exposure conferred robust protection against RSV challenge in BALB/c mice. These results underscore the potential of 4-H1-anti-HSA-4-H1 as a respiratory-delivered prophylactic against RSV.IMPORTANCERSV is the leading cause of infant respiratory hospitalizations, highlighting the urgent need for effective prophylaxis. Here, we engineered a potent bispecific nanobody (4-H1-anti-HSA-4-H1) that exhibits exceptional neutralization against both RSV A and B subtypes with prolonged serum persistence. Prophylactic intranasal delivery of this construct conferred robust protection against RSV challenge in mice, indicating its potential as a respiratory-delivered prophylactic candidate against RSV.

The persistence of latent HIV-1 reservoirs remains a critical barrier to cure. Current "shock and kill" strategies are limited by ineffective latency-reversing agents (LRAs) and poor understanding of epigenetic regulation. Here, we identify chromatin assembly factor 1 subunit A (CHAF1A), a histone chaperone enforcing HIV-1 latency, as a therapeutic target regulated by antagonistic post-translational modifications: ubiquitination promotes its degradation, while O-GlcNAcylation stabilizes it. We demonstrate that trifluridine, a Food and Drug Administration-approved antiviral drug, reactivates latent HIV-1 by disrupting O-GlcNAcylation, triggering CHAF1A ubiquitination and proteasomal degradation. Notably, CHAF1A expression increases with age in CD4⁺ T cells (>60 years), correlating with deeper proviral reservoirs. This age-dependent accumulation inversely associates with reduced O-GlcNAcase levels, suggesting O-GlcNAcylation-mediated stabilization in aging. Our findings establish CHAF1A as both a therapeutic target and an age-stratifying biomarker, advancing trifluridine as a translatable LRA to enhance reservoir clearance in aging populations-a demographic increasingly impacted by HIV-1 persistence.IMPORTANCEHIV-1 latency continues to represent a significant barrier to achieving a cure, particularly in aging populations characterized by expanded viral reservoirs and compromised immune recovery-a challenge further intensified by the absence of therapies specifically designed to target age-related mechanisms. Current latency-reversing agents (LRAs) are insufficient in addressing the metabolic and epigenetic dysregulation that sustains viral persistence in older individuals. In this study, we reveal a dynamic interplay between ubiquitination and O-GlcNAcylation that regulates the stability of CHAF1A, a histone chaperone essential for maintaining HIV-1 latency. We identify trifluridine as a novel LRA capable of disrupting O-GlcNAcylation to degrade CHAF1A, thereby effectively reversing latency in primary cells. This research bridges a critical gap between fundamental virology and clinical gerontology. These findings establish a robust foundation for refining strategies aimed at HIV-1 eradication, with a focus on targeting host metabolic-epigenetic networks to address latency in underserved aging populations.