PLoS Pathogens最新文献

The transmission of many plant viruses depends on arthropod vectors, which acquire viruses while feeding on infected plants and subsequently inoculate un-infected hosts. Efficient virus acquisition, particularly for persistently transmitted viruses, requires sustained vector feeding on infected plants. However, how vector infestation influences plant-virus interactions and the modulation of these impacts by viral factors remains poorly understood. Here, we show that whitefly infestation on begomovirus-infected plants activates host antiviral defenses through inducing salicylic acid (SA) accumulation. Betasatellites associated with begomoviruses, specifically the βC1 protein encoded therein, suppress these whitefly-induced defenses by interfering with SA accumulation and signaling. Mechanistically, βC1 interacts with Nicotiana benthamiana ENHANCED DISEASE SUSCEPTIBILITY 1 (NbEDS1), disrupting its interaction with NbPAD4 to reduce SA accumulation. Additionally, βC1 interferes with the association between NbEDS1 and NbTGA2, thereby attenuating NbTGA2-mediated transcription of SA-responsive genes. Our findings unravel a novel mechanism by which βC1 promotes begomovirus-whitefly compatibility, offering new insights into insect vector-mediated transmission of plant viruses.

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections in infants and the elderly worldwide. Although prophylactic monoclonal antibodies and RSV vaccines are available for preventing severe RSV infection, unmet medical need remains for an effective antiviral agent to treat patients who do not benefit from these interventions. Ziresovir (formerly AK0529) is a potent, selective, and orally bioavailable RSV fusion inhibitor with proved antiviral efficacy and clinical benefits. To understand the molecular mechanism of action, we computationally modeled ziresovir with the RSV fusion (F) protein. Here, we present a cryo-EM structure of the RSV F protein-ziresovir complex, elucidating the molecular interactions underlying the drug binding, revealing ziresovir specifically binds to the central cavity within the metastable prefusion conformation of RSV F protein. Leveraging this structural insight, we engineered site-directed RSV mutants guided by both the cryo-EM binding model and drug-resistant RSV variants for fusion inhibitors identified in vitro, and demonstrated that these resistant viruses do not replicate as efficient as wild-type RSV and indicated a fitness cost for viral escape from drug treatment. Collectively, these findings unveil the structural mechanism of ziresovir-mediated viral inhibition, providing a framework for developing the next-generation RSV fusion inhibitors.

Clade 2.2 H5N1 influenza viruses have caused an unusually high number of human infections, providing a unique opportunity to investigate early molecular steps associated with host adaptation. Although most work has focused on hemagglutinin (HA), the contribution of neuraminidase (NA) to these early adaptive events has remained unclear. By analyzing publicly available sequences from clade 2.2-infected patients, we identified 20 NA mutations and compared their phenotypes to 20 mutations acquired during diversification in primary human airway cells under drug-free conditions. Most patient-derived NA mutations resulted in modest reductions in sialidase activity, keeping activity within a functional range that supported improved replication in α2,6 sialylglycan (α2,6 Sia)-dominant environments, whereas excessive reduction impaired fitness. Notably, the phenotypes of culture-selected and patient-derived mutations were highly concordant, suggesting that these NA changes arose through natural selection rather than antiviral pressure. Re-analysis of patient sequences further revealed that many adaptive NA mutations co-occur with HA mutations that confer only weak, partial α2,6 Sia binding. Using reverse genetics, we found that such naturally occurring HA/NA mutation pairs acted cooperatively in a receptor-context-dependent manner to support α2,6-associated replication relative to HA-only mutants, placing these variants within a constrained "early-adaptation space" characterized by limited α2,6 engagement and moderately reduced NA activity. Together, these findings indicate that early human adaptation of clade 2.2 H5N1 involves not only HA and PB2, but also incremental, cooperative tuning of NA function. Monitoring coordinated HA-NA evolution may therefore improve risk assessment frameworks for zoonotic influenza viruses poised at early stages of human host adaptation.

Tegument proteins of human cytomegalovirus (HCMV) play essential roles in viral assembly, coordinating interactions among capsids, membranes, and host-derived components. pp28 (UL99), a dominant tegument protein expressed during late infection, is essential for cytoplasmic envelopment and proper trafficking to the viral assembly compartment (vAC). Here, we identify a critical role for palmitoylation in pp28 function. Using site-directed mutagenesis and acyl-resin assisted capture (acyl-RAC) assays, we show that palmitoylation occurs at conserved cysteine residues (Cys6, Cys10, Cys11) near the N-terminus. Disruption of these residues impairs pp28 stability, alters its subcellular localization, and reduces the release of infectious virions without affecting intracellular viral replication. Confocal imaging and proteasome inhibition experiments reveal that palmitoylation-deficient pp28 is more susceptible to degradation and fails to accumulate at ERGIC-derived membranes. Consistent with these findings, recombinant HCMVs encoding pp28 mutants impaired in palmitoylation exhibit reduced extracellular viral titers. These results define palmitoylation as a key modification of pp28 that ensures proper compartmental targeting and virion maturation, underscoring a broader role for tegument lipidation in herpesvirus assembly and egress.

Amdoparvoviruses are best known as agents of disease in carnivorans, but here we provide the first in-depth molecular evolutionary and ecological information for an amdoparvovirus in wild rodents (field voles, Microtus agrestis). We applied an RNA-sequencing approach in lung tissue that yielded high diagnostic sensitivity and multiple full or near-full coding sequences for the new virus (field vole amdoparvovirus, FVAV) in individual voles. FVAV is most similar to amdoparvoviruses in European foxes and wildcats. We present evidence that FVAV is an exogenous, endemic, high-prevalence infection with a short-term history of horizontal transmission and recombination within voles and arising from an ancestral background of dynamic host usage and inter-lineage recombination. FVAV molecular structures involved in host exploitation share a highly conserved functional and evolutionary pattern with those in other amdoparvoviruses. The more variable regions within these structures evolve principally by apparently neutral processes and FVAV within-population mutation distribution mirrors that across the Amdoparvovirus phylogeny. Nonetheless, we did find some evidence of adaptive selection in the most variable regions and we also found convergent host-specific features in the modelled capsid protein of divergent arvicoline-associated lineages that might tend to restrict host range and support that FVAV is a vole-specialist. Increasing FVAV expression was associated with pulmonary inflammation and suppressed splenic T-cell activation, consistent with a potential to drive disease processes as in other amdoparvoviruses. Importantly, our approach highlights the de novo sequence assembly of viral RNA products from shotgun sequencing of rRNA-depleted RNA from tropic tissues in individual hosts as a sensitive and robust means of detecting and characterising not only RNA viruses but also DNA viruses.

Radiation-induced lung injury (RILI) is a serious complication of thoracic radiotherapy, with limited effective treatment options. This study demonstrates that fecal microbiota transplantation (FMT) confers protection against RILI through modulation of the gut-lung axis. In a total lung irradiation (TLI) mouse model, FMT significantly alleviated pulmonary histopathological injury, inflammatory responses, oxidative stress, and collagen deposition during fibrogenesis. Concurrently, FMT improved intestinal motility, enhanced mucosal barrier integrity, and restored TLI-induced dysbiosis in gut microbiota diversity and community structure. Metabolomic analysis revealed that TLI significantly disrupted the metabolism of unsaturated fatty acids and arachidonic acid (AA), whereas FMT partially restored these metabolic networks. Transcriptomic and ultrastructural analyses indicated that RILI suppressed endoplasmic reticulum (ER) protein processing and induced ER swelling, while FMT promoted protective ER-phagy and facilitated restoration of ER morphology. Integrated multi-omics analysis further identified the AA metabolism as a key component of FMT-mediated protection, with its alterations closely associated with pulmonary tissue repair. Further in vivo and in vitro experiments demonstrated that AA binds to and activates the nuclear receptor PPARγ, leading to transcriptional upregulation of FAM134B, promoting protective ER-phagy and ameliorating RILI. In summary, this study highlights the bidirectional gut-lung axis as a therapeutic target in RILI progression and intervention, and reveals that FMT confers protection through metabolic remodeling and activation of the PPARγ-FAM134B-mediated ER-phagy pathway, providing a mechanistic basis for potential clinical translation.