Search Results (170)

West Nile virus (WNV) is a mosquito-borne pathogen of escalating epidemiological importance and a growing global health concern, driven by the climate-associated expansion of its Culex mosquito vectors. Although WNV is an extensively studied flavivirus, most host–pathogen interaction studies focus on static and structural aspects rather than dynamic and functional ones. Delineating phosphorylation-mediated interactions between WNV proteins and human kinases bridges a critical gap by providing important insight into the molecular mechanisms underlying infection. In this study, we investigated potential phosphorylation-mediated interactions between WNV proteins and human kinases using an integrative computational framework combining motif prediction, phosphoproteomic data analysis and structural docking. Key interactions were predicted between viral proteins and regulatory kinases within the AKT-ERK pathway and the AMPK-mediated autophagy, including major network kinases such as RAF1, IKBKB, and ULK1. In addition, experimentally validated phosphorylation sites in viral proteins were found to be associated with multiple candidate host kinases, including MAP2K7 and MAP2K9, suggesting complex regulatory networks. Integration with phosphoproteomic datasets supported the relevance of multiple predicted kinases, including those associated with antiviral responses and translational regulation. Protein–protein docking demonstrated stable, energetically favorable interactions between selected host kinases and viral proteins, particularly the viral polymerase (NS5), helicase (NS3), and NS1. The findings of this study establish a framework for future research on the development of host-directed antiviral strategies. Full article

Human noroviruses (HuNoVs) are a leading cause of acute gastroenteritis worldwide, yet no effective antiviral therapeutics are currently available. Although environmentally induced capsid conformational changes associated with infectivity have been reported in murine noroviruses (MNVs), comparable conformational switching has not been demonstrated in HuNoVs. In this study, we generated HuNoV GII.3 virus-like particles (VLPs) using a baculovirus expression system and identified two distinct T = 3 particle populations coexisting within VLP preparations derived from a single strain through cryo-electron microscopy single-particle analysis. Comparative structural analysis revealed that these two T = 3 capsid conformations correspond to the resting and rising states of the protruding (P) domain. Rearrangement of the P domain alters intermolecular interactions between adjacent capsid subunits, resulting in distinct capsid surface architectures. In the resting state, intermolecular contacts were mediated predominantly by the P2 subdomain, with limited contribution from the P1 subdomain. In contrast, the rising state exhibited a shift toward an alternative interaction interface primarily involving the P1 subdomain. The alteration of the capsid surface accompanying this conformational switching can influence biologically relevant intermolecular interactions with viral hosts and antibodies as demonstrated in murine norovirus. These findings demonstrate previously unrecognized structural polymorphism in the HuNoV capsid and provide evidence that conformational switching may occur in HuNoVs. Our results offer new insights into norovirus capsid dynamics and may inform future structure-based vaccine and antiviral drug development. Full article

Nipah virus (NiV) is a highly lethal zoonotic pathogen with significant pandemic potential, for which no approved antiviral therapies are currently available. Viral entry is mediated by the interaction between the NiV attachment glycoprotein (NiV-G) and host ephrin receptors, particularly ephrin-B2 (EFNB2) and ephrin-B3 (EFNB3), making this interface an attractive therapeutic target. In this study, we evaluated a set of structurally related flavonoids, apigenin, cynaroside, and lonicerin, as potential modulators of the EFNB2–NiV-G and EFNB3–NiV-G interactions. These compounds were selected based on their structural similarity, reported antiviral activity, chemical diversity, and favorable drug-like properties. Apigenin was employed as a reference scaffold due to its well-characterized pharmacological profile and its suitability for guiding analog-based compound selection. Apigenin served as a reference scaffold for selecting structurally related flavonoids, which were analyzed through density functional theory optimization, molecular docking, pharmacokinetic and toxicity predictions, molecular dynamics simulations, and binding free energy calculations. These flavonoids demonstrated high predicted affinity for both the EFNB2–NiV-G and EFNB3–NiV-G interfaces. According to results, these compounds consistently interacted with residues known to play a critical role in receptor recognition, with special emphasis on leucine and tryptophan residues within the G–H loop. These residues are well established as key determinants in the entry process of Nipah virus (NiV) into host cells, highlighting the potential relevance of these flavonoid–protein interactions. Molecular dynamics analyses indicated that flavonoid binding reduced the affinity and the conformational flexibility at the receptor–glycoprotein interfaces and decreased the stability of the complexes. Pharmacokinetic and toxicity predictions suggested favorable drug-like properties for the flavonoids, with apigenin displaying the most balanced profile. Collectively, these results support the potential of selected flavonoids as modulators of EFNB2–NiV-G and EFNB3–NiV-G interactions and provide a rationale for their prioritization in experimental studies aimed at developing scaffolds for the modulation of viral entry against Nipah virus. Full article

Feline panleukopenia virus (FPV) causes severe enteric and systemic disease in cats, with particular importance in shelter environments where susceptible kittens, high population turnover, environmental contamination, and variable vaccination histories increase infection pressure. Recent virome and microbiome studies suggest that FPV-associated enteritis may occur within a broader context of viral co-detection and intestinal microbial disturbance, but direct FPV-specific bacteriome evidence remains limited. This review aims to synthesize current evidence on FPV-associated enteritis in shelter cats by integrating viral pathogenesis, diagnostic interpretation, enteric virome co-detection, gut dysbiosis, recovery dynamics, and intervention-related ecological effects. The literature was organized using an evidence-tier framework that distinguishes direct FPV/feline panleukopenia evidence from feline enteric microbiome proxy evidence and broader comparative or mechanistic microbiome studies. This approach was used to define the limits of inference and to separate evidence-supported conclusions from hypothesis-generating ecological models. Feline panleukopenia in shelter cats should be interpreted not only as an individual viral infection, but also as an ecological process shaped by host susceptibility, shelter exposure, diagnostic complexity, viral co-detection, and microbial community disturbance. Current evidence supports a cautious framework in which virome co-detection and dysbiosis-associated patterns are not treated as direct proof of causation. Future longitudinal, context-controlled, and multi-layer studies integrating validated FPV diagnostics, virome and bacteriome profiling, clinical metadata, treatment records, and functional endpoints are needed to clarify the biological and clinical significance of gut ecosystem disruption in feline panleukopenia. Full article

The concurrent circulation of influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has unveiled complex host–pathogen interactions governed by temporal dynamics of innate immune activation. This narrative review synthesizes evidence from human air–liquid interface (ALI) epithelial models, animal studies (hamster, ferret), clinical cohorts, and randomized controlled trials (2015–2026) to delineate the molecular mechanisms underlying viral interference between these two major respiratory pathogens. Prior IAV infection induces a robust type I/III interferon (IFN) response and broad interferon-stimulated gene (ISG) upregulation that restricts subsequent SARS-CoV-2 replication within a critical 24–72 h temporal window. Conversely, SARS-CoV-2 employs a multi-layered immune evasion strategy that blunts IFN induction, providing minimal heterologous protection. Simultaneous co-infection tends to exacerbate disease severity. Host genetic determinants, including OAS1 and TLR7 variants, modulate interference capacity. Therapeutically, early pegylated IFN-λ shows clinical benefit, while experimental evidence from in vitro and animal models suggests oseltamivir may paradoxically reduce IAV-induced interference. These findings underscore the need for multi-pathogen diagnostics, temporally informed clinical decision-making, and IFN-based therapeutic strategies during co-circulation periods. Full article

Avian orthoreovirus (ARV) has re-emerged as one of the most important viral pathogens affecting modern poultry production worldwide. In China, the epidemiological landscape of ARV has undergone a substantial transformation over the past decade, characterized by increasing genotypic diversity, frequent genome reassortment, an expanding host range, and recurrent vaccine-breakthrough outbreaks. Growing evidence indicates that contemporary ARV populations evolve within a dynamic multispecies transmission network shaped by intensive poultry production, host adaptation, and vaccine-associated selective pressures. Recent molecular studies have revealed extensive genetic heterogeneity among circulating strains and highlighted the limitations of conventional σC-based classification systems for accurately describing viral evolution, pathogenicity, and antigenic diversity. Whole-genome analyses further demonstrate that reassortment among chicken-origin, duck-origin, and goose-origin orthoreoviruses plays a pivotal role in generating novel viral variants with altered biological properties. In parallel, accumulating evidence suggests that ARV exerts broad immunomodulatory effects through the disruption of innate antiviral signaling, impairment of lymphoid organ function, interference with vaccine responsiveness, and the enhancement of susceptibility to secondary infections. These findings indicate that ARV should be regarded not only as an arthrotropic pathogen but also as an important immunopathological agent influencing flock health and productivity. This review summarizes current knowledge of ARV in China, with an emphasis on molecular epidemiology, genomic evolution, reassortment mechanisms, transmission ecology, immune interference, vaccine escape, and integrated prevention strategies. Particular attention is given to the increasing importance of whole-genome surveillance, phylodynamic analysis, and multispecies epidemiological monitoring for understanding contemporary ARV evolution. Future perspectives involving structural vaccinology, precision immunization, metagenomics-assisted surveillance, and predictive evolutionary modeling are also discussed. Collectively, sustainable ARV control will likely require genome-informed and adaptive prevention frameworks integrating virology, immunology, epidemiology, and precision poultry management. Full article

Background: Viral attachment mediated by host cell surface receptors is the first step in viral infection. As a key cell surface receptor, heparan sulfate (HS) mediates the attachment and entry of numerous non-enveloped viruses in livestock, thereby serving as a crucial molecular target for studying virus–host interactions. Methods: Based on the structural scaffold of a nanobody (Nb; PDB: 7TJC), we rationally designed and constructed a mutant Nb targeting HS, designated HS-Mut-Nb1, using molecular docking, site-directed mutagenesis, molecular dynamics (MD) simulations, and experimental characterization. Results: Molecular docking indicated that the active site of wild-type Nb for HS binding was located within the cavity jointly formed by the complementarity-determining region 3 (CDR3) and the framework regions (FRs) of the wild-type Nb. A comprehensive analysis integrating virtual alanine scanning, site-directed mutagenesis, and MD simulations revealed that the combination of three point mutations (Phe47Arg, Asp99Tyr, and Tyr108Pro) significantly enhanced the binding affinity of Mut-Nb1 for HS, with a calculated binding free energy (ΔG) of −83.26 ± 3.06 kcal/mol. Enzyme-linked immunosorbent assay (ELISA) results further confirmed that Mut-Nb1 exhibited high affinity for HS (K_D = 65.87 nM) and specificity (positive/negative ratio, P/N = 3.84; cross-reactivity, CR < 6.60%). Conclusions: This study not only provides novel candidate molecules for elucidating the mechanism of HS–virus interactions and developing related inhibitors but also offers a reference for the rapid construction of mutant Nbs. Full article

Essential host functions are often maintained by conserved molecular systems, but in biological contexts shaped by evolutionary conflict, the genes that execute such functions may be unstable, replaceable, or repeatedly recruited from different evolutionary sources. Mammalian placentation provides a striking example of this principle. Trophoblast cell fusion is essential for placental development, yet this function is mediated in different mammalian lineages by distinct endogenous retrovirus-derived envelope proteins, including syncytin-1, syncytin-2, and other lineage-specific Env-derived fusogens. Here, I propose the Baton Pass model as a conceptual framework for explaining how host-level biological functions can be maintained despite turnover of the molecular agents that execute them. This model differs from conventional examples of antagonistic coevolution, which often emphasize recurrent mutations within the same interacting genes, and from non-orthologous gene displacement, which generally concerns replacement among cellular genes. In the syncytin paradigm, the molecular executors are repeatedly supplied by exogenous retroviral env genes that become endogenized, domesticated, and incorporated into host developmental programs. I further discuss how receptor compatibility, placental expression control, and host–virus evolutionary conflict may together destabilize individual Env–receptor systems while allowing the host-level function of trophoblast fusion to persist. Analogous functional reassignment is also observed in primate lentiviruses, where antagonism of BST-2 shifts among distinct viral genes. The Baton Pass model therefore describes a testable evolutionary principle: essential host functions can be preserved not only through conservation of specific genes, but also through dynamic succession of genes of distinct evolutionary origins. Full article

This work presents a spatially explicit 19-variable reaction–diffusion model for within-host SARS-CoV-2 dynamics that integrates viral kinetics, innate and adaptive immune responses, cytokine regulation, antibody production, and tissue-level thermoregulatory dynamics. Adaptive immune recruitment is described through smooth sigmoidal activation functions, whereas pro-inflammatory cytokines are controlled by Michaelis–Menten-type saturation with IL-10 feedback. The thermoregulatory component is formulated as a downstream tissue-level inflammatory readout driven by bounded virus-dependent pyrogenic forcing, homeostatic relaxation, and effective thermal diffusion. The system is solved using a meshless multiquadric radial basis function collocation method based on Kansa’s formulation. Numerical simulations reproduce the qualitative progression of acute infection, including early viral expansion, innate immune activation, delayed adaptive recruitment, and immune-mediated clearance. Spatial analysis reveals heterogeneous tissue-level patterns, such as localized viral foci, antibody depletion near the infection center, delayed cytotoxic effector coverage, and transient thermal gradients. The proposed framework provides a biologically interpretable and computationally flexible approach for investigating the spatiotemporal organization of within-host SARS-CoV-2 immune dynamics, while remaining a mechanistic modeling study rather than a patient-specific clinical predictor. Full article

In this study, we combined computational predictions with experimental validation as a hybrid strategy to explore whether the E protein of tick-borne encephalitis virus (TBEV) possesses autoimmune potential. Using in silico homology searches, we identified two viral epitopes (evglekl and vtgtqgt) within the TBEV E protein that share sequence identity with fragments of the human proteins DNAH7 and CSMD2. Antibodies against these epitopes were detected in the plasma of a subset of patients after natural TBEV infection. Notably, no such antibodies were found in recipients of the Tick-E-Vac vaccine, indicating that the current vaccine does not induce cross-reactive humoral responses to these epitopes. Further computational analysis predicted that these epitopes could be presented by HLA class II molecules (alleles DRB1*09:01 and DRB1*07:01), which are known to be associated with autoimmune pathologies. Molecular dynamics simulations confirmed stable binding of the peptides within the HLA grooves, with favorable binding energies. These findings suggest a possible involvement of T-helper cells in the autoreactive process. Natural TBEV infection can give rise to antibodies against epitopes homologous to human proteins, particularly in genetically predisposed hosts. While such homology alone does not predict the onset of autoimmune disease, it represents a risk factor. Full article

A within-host HIV dynamics model incorporating latent reservoirs, distributed time delays, and a B-cell-mediated humoral immune response is developed and analyzed mathematically. The model includes five compartments: uninfected CD4⁺ T cells, latently infected cells, actively infected cells, free virions, and B cells. Four distinct distributed delays are introduced to account for the periods between viral entry and the emergence of latently or actively infected cells, reactivation of latently infected cells, and intracellular virion production. For the non-delayed system, the basic reproduction number ${\mathcal{R}}_0$ is derived using the next-generation matrix method. Using Lyapunov functions and LaSalle’s Invariance Principle, a sharp threshold dynamic is proven: the infection-free equilibrium is globally asymptotically stable (GAS) when ${\mathcal{R}}_0\le 1$, whereas a unique endemic equilibrium is GAS when ${\mathcal{R}}_0>1$. For the full distributed-delay system, a delay-dependent reproduction number ${\mathcal{R}}_0^d$ is defined. The global asymptotic stability of the infection-free equilibrium is established for ${\mathcal{R}}_0^d\le 1$, and the global asymptotic stability of the endemic equilibrium is established for ${\mathcal{R}}_0^d>1$, using suitably constructed Lyapunov functionals that account for the delay history. Numerical simulations validate the analytical threshold behavior. A sensitivity analysis of ${\mathcal{R}}_0^d$ identifies the most influential parameters for potential intervention. A treatment-dependent reproduction number is derived, and the critical drug efficacy required for viral eradication is determined. The intracellular production delay is shown to act as a critical threshold for infection clearance. Full article

Virophages are satellite viruses that depend on the replication machinery of giant double-stranded DNA viruses and influence the structure and dynamics of viral communities through multilayered interactions among giant viruses, their hosts, and virophages. Since the discovery of the Sputnik virophage in 2008, virophages have been increasingly recognized for their roles in regulating giant virus replication, contributing to host defense mechanisms, and shaping the evolution of mobile genetic elements. However, quantitative syntheses examining how virophage research has developed over time, particularly in marine environments, remain limited. Here, we conducted a bibliometric analysis of virophage research published between 2008 and 2025 using the Web of Science Core Collection. By comparing an overall virophage research corpus with a marine virophage sub-corpus, we assessed publication and citation trends, collaboration structures, and keyword-based intellectual and thematic evolution. Our results show that virophage research has gradually transitioned from an early phase dominated by landmark discoveries and experimental model systems to a data-intensive stage driven by genome- and metagenome-based analyses and computational approaches. Although marine virophage studies represent a relatively small proportion of the total literature, they exhibit sustained citation impact and form a distinct research axis within the field. In particular, marine-focused studies emphasize metagenomic discovery, genome sequence alignment, and the analysis of mobile genetic elements such as polinton-like viruses, highlighting the role of marine environments in accelerating the intellectual transition of virophage research. Collectively, these findings demonstrate that virophage research has moved beyond a “discovery and definition” phase toward data-driven integrative interpretation, with marine virophage research emerging as a key domain for understanding the structure and evolutionary dynamics of marine viral ecosystems. Full article

Waterhemp (Amaranthus tuberculatus (Moq.) J. D. Sauer) is one of the most competitive and herbicide-resistant weed species in soybean cropping systems across North America. While its competitive and adaptive traits are well-documented, its role as an alternative host for plant pathogens remains underexplored. This review synthesizes current knowledge on fungal, bacterial, viral, and nematode pathogens that infect waterhemp and examines the ecological and management implications of these interactions. We discuss how waterhemp may serve as a reservoir for inoculum, potentially influencing disease dynamics in soybean under changing climate conditions. Furthermore, we assess the potential of host-specific pathogens as biological control agents within the integrated weed management (IWM) approach. Despite promising experimental results, several barriers limit large-scale adoption of bioherbicides, including environmental sensitivity, narrow host specificity, challenges in mass production, and regulatory constraints. Understanding weed–pathogen interactions could inform dual-purpose strategies that reduce both weed pressure and disease risk in soybean systems. Further research is needed to optimize biocontrol scalability, assess climate-driven epidemiological shifts, and develop robust integrated weed and disease management approaches. Full article

The membrane fusion process, mediated by the entry fusion complex (EFC) of the monkeypox virus (MPXV), is crucial for host cell invasion. Apolipoprotein B mRNA Editing Catalytic Polypeptide-like 3 (APOBEC3)-driven mutation bias is a key factor in MPXV’s adaptive evolution during its global spread. However, how these mutations affect the structure and function of EFC proteins remains poorly understood. To address this, we performed genomic mutation analysis on globally circulating MPXV clades Ib and IIb, combined with protein monomer, binary, and quaternary complex structure modeling based on AlphaFold 3 and experimental validation by ELISA. We first delineated the mutational spectra of all 11 EFC proteins, revealing that although EFC proteins in clade Ib are highly conserved, lineage IIb B exhibits extensive APOBEC3-driven mutations and the G9 M142I mutation is identified as a lineage-associated APOBEC3-type mutation of lineage IIb B. Structural predictions revealed that while the M142I mutation does not alter G9 monomer folding, it induces a conformational shift in the G9/A16 subcomplex. Furthermore, within the predicted G9/A16/A56/K2 quaternary complex, this mutation enlarges the interfacial gap and reduces docking stability between the G9/A16 subcomplex and A56/K2. Experimental validation demonstrated that the M142I mutation significantly reduces the binding affinity of G9 for A16 and impairs the recruitment of A56/K2 to the quaternary complex, confirming the computationally predicted mechanism of interface destabilization. These findings highlight a dynamic interplay between APOBEC3-driven evolution and EFC protein structure, demonstrating that the M142I mutation alters EFC complex assembly dynamics and may shift the regulatory balance of the membrane fusion system. These structural changes provide molecular insights into MPXV lineage differentiation, though direct functional assays are required to determine the net effect on viral entry efficiency. Full article

Wheat streak mosaic (WSM), historically attributed to wheat streak mosaic virus (WSMV) and transmitted by the wheat curl mite (WCM; Aceria tosichella), remains a major cause of yield loss in the Texas High Plains. In recent years, Triticum mosaic virus (TriMV), also transmitted by WCM, has emerged as an increasingly important component of the WSM disease complex. Under field conditions, TriMV is most frequently detected in mixed infections with WSMV. Management of WSM relies primarily on resistant cultivars carrying genes such as Wsm1 or Wsm2. Although synergistic interactions between WSMV and TriMV have been documented under controlled conditions, their dynamics during natural field infections—particularly during the latent phase between initial infection and symptom development—remain poorly understood. Moreover, the extent to which host genotype influences virus–virus interactions and vector acquisition dynamics in the field has not been fully resolved. Replicated field trials conducted over two growing seasons were used to quantify temporal accumulation patterns and relative ratios of WSMV and TriMV in susceptible (TAM 304) and resistant cultivars differing in resistance source (BT [Wsm1] and Joe [Wsm2]) under natural disease spread. WSMV remained the predominant virus in mixed infections across cultivars, sampling times, and disease stages. However, as plants aged and entered senescence, WSMV titers declined more rapidly than TriMV titers, resulting in a progressive reduction in the WSMV-to-TriMV ratio. From early infection through disease development, the Wsm1 cultivar (BT) consistently supported significantly lower TriMV accumulation than the Wsm2 cultivar (Joe), providing a mechanistic explanation for the comparatively stronger disease suppression associated with WSM. Mites feeding on BT also acquired lower TriMV titers. Although viral concentrations in wheat tissue were strongly correlated with those detected in feeding mites, substantial differences in plant-level WSMV-to-TriMV ratios among cultivars were not mirrored within the vector. These findings indicate that while host resistance regulates absolute virus accumulation, vector-associated factors may influence the relative proportions of viruses detected following acquisition, with important implications for WSM epidemiology and resistance deployment in field systems. Full article