Search Results (2,863)

Background/Objectives: Rotavirus remains a major cause of severe acute gastroenteritis
in infants worldwide. The suboptimal efficacy of current vaccines underscores the need
for alternative microbiome-based interventions, including postbiotics. Extracellular
vesicles (EVs) from probiotic and commensal E. coli strains have been shown to mitigate
diarrhea and enhance immune responses in a suckling-rat model of rotavirus infection.
Here, we investigate the regulatory mechanisms activated by EVs in rotavirus-infected
enterocytes. Methods: Polarized Caco-2 monolayers were used as a model of mature
enterocytes. Cells were pre-incubated with EVs from the probiotic E. coli Nissle 1917 (EcN)
or the commensal EcoR12 strain before rotavirus infection. Intracellular Ca²⁺
concentration, ROS levels, and the expression of immune- and barrier-related genes and
proteins were assessed at multiple time points post-infection. Results: EVs from both
strains exerted broad protective effects against rotavirus-induced cellular dysregulation,
with several responses being strain-specific. EVs interfered with viral replication by
counteracting host cellular processes essential for rotavirus propagation. Specifically, EV
treatment significantly reduced rotavirus-induced intracellular Ca²⁺ mobilization, ROS
production, and COX-2 expression. In addition, both EV types reduced virus-induced
mucin secretion and preserved tight junction organization, thereby limiting viral access
to basolateral coreceptors. Additionally, EVs enhanced innate antiviral defenses via
distinct, strain-dependent pathways: EcN EVs amplified IL-8-mediated responses,
whereas EcoR12 EVs preserved the expression of interferon-related signaling genes.
Conclusions: EVs from EcN and EcoR12 act through multiple complementary
mechanisms to restrict rotavirus replication, spread, and immune evasion. These findings
support their potential as effective postbiotic candidates for preventing or treating
rotavirus infection. Full article

Although the SARS-CoV-2 pandemic no longer poses a global emergency, the virus continues to diversify and acquire immunoevasive properties. Understanding the molecular pathways that shape SARS-CoV-2 pathogenesis has become essential. In this paper, we summarize the most recent current evidence on how the spike protein structurally evolves, on changes in key non-structural proteins, such as nsp14, and on host factors, such as TMPRSS2 and neuropilin-1. These changes, together, shape viral entry, replication fidelity and interferon antagonism. Given the emerging Omicron variants of SARS-CoV-2, recent articles in the literature, cryo-EM analyses, and artificial intelligence-assisted mutational modeling were analyzed to infer and contextualize mutation-driven mechanisms. It is through these changes that the virus adapts and evolves, such as optimizing angiotensin-converting enzyme binding, modifying antigenic surfaces, and accumulating mutations that affect CD8⁺ T-cell recognition. Multi-omics data studies further support SARS-CoV-2 pathogenesis through convergent evidence linking viral adaptation to host immune and metabolic reprogramming, as occurs in myocarditis, liver injury, and acute kidney injury. By integrating proteomic, transcriptomic, and structural findings, this work presents how the virus persists and dictates disease severity through interferon antagonism (ORF6, ORF9b, and nsp1), adaptive immune evasion, and metabolic rewiring. All these insights underscore the need for next-generation interventions that provide a multidimensional framework for understanding the evolution of SARS-CoV-2 and guiding future antiviral strategies. Full article

Our laboratory identified the susceptible allelic variant of equine CXCL16 protein (EqCXCL16S) as an entry receptor for equine arteritis virus (EAV). However, EAV has a broad host cell tropism and infects cells that lack EqCXCL16S. Thus, we hypothesized that EAV interacts with other host cell protein(s) that facilitate EAV infection. A virus overlay protein-binding assay in combination with a Far-Western blot from EAV-susceptible equine pulmonary artery endothelial cells (EECs) and equine dermal fibroblasts (E. Derm) identified a 57 kDa protein, present in the membrane fraction of the protein lysate, as a possible EAV-binding protein. Subsequent LC-MS/MS analysis identified this 57 kDa protein as vimentin. Screening of different mammalian cell lines has shown that only cells expressing vimentin are susceptible to EAV infection. Pre-treatment of EECs with an anti-vimentin polyclonal antibody and Withaferin A partially inhibit EAV infection. Finally, the overexpression of equine vimentin (EqVim) in HEK-293 cells increases their susceptibility to EAV infection. Overall, our data strongly indicate that EAV binds to the host cell protein equine vimentin, which actively participates in EAV infection, potentially serving as an attachment factor. The data suggest that EAV interacts with various host cell proteins to achieve its diverse cell tropism. Full article

Avian influenza viruses are predominantly associated with waterfowl and shorebirds, and are rarely detected in other avian hosts in nature. In 2021, an H1N1 virus was isolated from a Fieldfare Turdus pilaris in Zaporizhzhia Oblast, Ukraine. A phylogenetic analysis revealed that all eight gene segments belonged to the Eurasian low-pathogenic avian influenza lineages. The highest nucleotide identity of the HA gene was observed with viruses detected in Georgia, Sweden, and Ukraine (99.11%), while the NA gene showed the greatest identity to viruses from Western Europe (99.14–99.57%). Genetic analysis of the HA cleavage site showed a sequence (PSIQSR↓GLF) that contained a single basic amino acid. No deletions were detected in the stalk region of NA gene, and no specific mutations in PB2 protein were found. However, several amino acid substitutions were identified in the HA gene (D204E, S207T, and D239G) that may affect the binding affinity to specific antibodies. The occurrence of this virus in a wild, seemingly healthy thrush indicate that additional surveillance in poorly studied ecological groups such as Passeriformes is warranted. Full article

RNA viruses are major pathogens in fish, causing high mortality and substantial economic losses in aquaculture. To uncover conserved antiviral mechanisms, we investigated the response of turbot (Scophthalmus maximus) to viral hemorrhagic septicemia virus (VHSV), infectious pancreatic necrosis virus (IPNV), and red-spotted grouper nervous necrosis virus (RGNNV) using a comparative proteomic approach complemented by in vivo and in vitro functional assays. Proteomic analyses revealed the central, conserved role of proteins involved in reactive oxygen species (ROS) production and redox homeostasis during early infection. Functional assays using head kidney-derived leukocytes identified neutrophils and macrophages as the primary ROS producers and showed that the modulation of cytoplasmic and mitochondrial ROS, as well as ROS-dependent DNA release, follows virus-specific patterns. The pharmacological inhibition of NADPH oxidase and mitochondrial ROS significantly affected viral replication, demonstrating the direct role of ROS in viral pathogenicity. Collectively, these findings highlight redox modulation as a conserved host response in teleost fish during RNA virus infection, linking oxidative stress regulation to viral progression. This knowledge provides a foundation for developing broad-spectrum therapeutic or preventive strategies to enhance disease resistance and promote sustainable aquaculture. Full article

Mammarenaviruses (MaAv) cause persistent infection in their natural rodent hosts across the world and, via zoonotic events, can cause severe disease in humans. Thus, the MaAv Lassa virus (LASV) in Western Africa and the Junin virus (JUNV) in the Argentinean Pampas cause hemorrhagic fever diseases with significant case fatality rates in their endemic regions. In addition, the globally distributed MaAv lymphocytic choriomeningitis virus (LCMV) is an underrecognized human pathogen of clinical significance capable of causing devastating infections in neonates and immunocompromised individuals. Despite their impact on human health, there are currently no FDA-approved vaccines or specific antiviral treatments for MaAv infections. Existing anti-MaAv therapies are limited to the off-label use of ribavirin, whose efficacy remains controversial; hence, the development of novel therapeutics to combat human pathogenic MaAv is vital. We employed a high-throughput cell-based infection assay to screen the Pandemic Response Box, a collection of 400 diverse compounds with established antimicrobial activity, for MaAv inhibitors. We identified Ro-24-7429, an antagonist of the HIV-1 Tat protein and RUNX family transcription factor 1 inhibitor; WO 2006118607 A2, a dihydroorotate dehydrogenase inhibitor; and verdinexor, a novel selective inhibitor of nuclear export (SINE) targeting the XPO1/CRM1, as potent anti-MaAv compounds. Consistent with their distinct validated targets, verdinexor and WO 2006118607 A2 exhibited very strong synergistic antiviral activity when used in combination therapy. Our findings pave the way for the development of verdinexor as a potent host-directed antiviral against MaAv, which could be integrated into the development of combination therapy with direct- or host-acting antivirals to combat human pathogenic MaAv. Full article

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), poses a severe threat to global wheat production. The adaptor protein complex AP-1 plays a crucial role in vesicular trafficking, yet its function in rust fungi remains poorly understood. In this study, a gene encoding an AP-1 σ subunit, designated PsAP1, was identified in Pst. The expression of PsAP1 was highly induced during the early infection stage. Heterologous expression of PsAP1 in a Fusarium graminearum mutant partially restored its pathogenic defects. Subcellular localization analysis revealed that PsAP1 localizes to the plasma membrane, cytoplasm, and nucleus. Silencing PsAP1 in wheat using Barley stripe mosaic virus-mediated host-induced gene silencing (BSMV-HIGS) significantly attenuated Pst pathogenicity, reducing hyphal growth by 6.7% (colony diameter), sporulation by 61.6% (lesion length), and pathogen biomass by 66%, along with enhanced accumulation of host reactive oxygen species. Transcriptomic analysis further demonstrated that silencing PsAP1 disrupted multiple pathways, including MAPK signaling, glutathione metabolism, and carbohydrate metabolism. These findings indicate that PsAP1 facilitates Pst infection by modulating vesicular trafficking, suppressing host immunity, and reprogramming host metabolism. This study provides novel insights into the pathogenic mechanisms of rust fungi and suggests a potential target for disease control. Full article

Severe acute respiratory syndrome coronavirus (SARS-CoV) assembles and buds from the Golgi apparatus or the ER membrane, but the specific membrane microdomains utilized during this process remain underexplored. Here, we show that co-expression of the SARS-CoV structural proteins S, M, and N in HEK-293T cells is sufficient to generate genome-free SARS-CoV-like virus-like particles (VLPs), which preferentially bud from glycolipid-enriched membrane lipid raft microdomains. Immunofluorescence microscopy using raft-selective dyes (DiIC16) and spike-specific antibodies revealed strong co-localization of VLPs with lipid rafts. Detergent-resistant membrane analysis and sucrose gradient centrifugation further confirmed the presence of S protein in buoyant, raft-associated fractions alongside the raft marker CD44. Importantly, pharmacological disruption of rafts with methyl-β-cyclodextrin reduced VLP budding and S protein partitioning into raft domains, underscoring the requirement for intact lipid rafts in assembly. Additionally, our data support lipid raft-associated proteins’ (e.g., FNRA, VIM, CD59, RHOA) roles in modulating cellular responses conducive to viral replication and assembly. These findings highlight lipid rafts as crucial platforms for SARS-CoV morphogenesis and suggest new avenues for vaccine and antiviral development using VLPs and raft-targeting therapeutics. Full article

Mumps virus (MuV) is a single-stranded, negative-sense RNA virus of the Family Paramyxoviridae. MuV is a highly contagious human pathogen that causes primarily mild symptoms, including hallmark swelling of the parotid glands. Severe cases can occur, leading to neurological complications, including deafness, meningitis, and encephalitis. The mumps vaccine, now included in combination with measles and rubella vaccines (MMR), was first made available in the 1960s. After its introduction, mumps incidence dropped dramatically to less than 500 cases annually in the US. However, even with long-standing vaccination programs, MuV continues to challenge the landscape of public health due to a resurgence of cases in the past several decades and a still present lack of approved antiviral drugs and treatments available for the disease. This review will explore the biology of MuV, focusing on how MuV replicates and interacts with the host immune system. Recent studies have also shed light on the role of protein phosphorylation in regulating viral RNA synthesis—particularly the dynamic interactions between the nucleoprotein (NP) and phosphoprotein (P)—offering new insights into how the virus controls its replication machinery both mechanistically and through utilizing host cell advantages. We also examine how the immune system responds to mumps infection and vaccination, and how those responses may vary across viral genotypes. Although the Jeryl Lynn vaccine strain has played a key role in controlling mumps for decades, outbreaks among vaccinated individuals have raised questions about the present vaccine’s efficacy against circulating and emerging genotypes and if novel strategies will be required to prevent future outbreaks. We review current epidemiological data, highlighting shifts in MuV transmission and genotype distribution, and discuss the need for updated or genotype-matched vaccines. By connecting molecular virology with real-world trends in disease spread and vaccine performance, this review aims to support ongoing efforts to strengthen mumps control strategies and inform the development of next-generation vaccines. Full article

Coxsackievirus B3 (CVB3) is a picornavirus that causes systemic inflammatory diseases including myocarditis, pericarditis, pancreatitis, and meningoencephalitis. We have previously reported that CVB3 induces mitochondrial fission and mitophagy while inhibiting lysosomal degradation by blocking autophagosome-lysosome fusion. This promotes the release of virus-laden mitophagosomes from host cells as infectious extracellular vesicles (EVs), enabling non-lytic viral egress. Transient receptor potential vanilloid 1 (TRPV1), a heat and capsaicin-sensitive cation channel, regulates mitochondrial dynamics by inducing mitochondrial membrane depolarization and fission. In this study, we found that TRPV1 activation by capsaicin dramatically enhances CVB3 egress from host cells via EVs. Released EVs revealed increased levels of viral capsid protein VP1, mitochondrial protein TOM70, and fission protein phospho-DRP1. Moreover, these EVs were enriched in heat shock protein HSP70, suggesting its role in facilitating infectious EV release from cells. Furthermore, TRPV1 inhibition with capsazepine and SB-366791 significantly reduced viral infection in vitro. Our in vivo studies also found that SB-366791 significantly mitigates pancreatic damage and reduces viral titers in a mouse model of CVB3 pancreatitis. Given the lack of understanding regarding factors that contribute to diverse clinical manifestations of CVB3, our study highlights capsaicin and TRPV1 as potential exacerbating factors that facilitate CVB3 dissemination via mitophagy-derived EVs. Full article

Influenza A virus (IAV) continues to present a threat to public health, highlighting the need for safe and multi-target antivirals. In this study, anti-influenza activity, airborne transmission blocking capacity, and immunomodulatory effects of Cnidium monnieri polysaccharides (CMP) were evaluated. Cytotoxicity in A549 cells was assessed by CCK-8 (CC₅₀ = 8.49 mg/mL), antiviral efficacy against A/California/04/2009 (CA04) by dose–response (EC₅₀ = 1.63 mg/mL), and the stage of action by time-of-addition assays (pre-, co-, post-treatment). A guinea pig model infected with CA04 was used for testing the effect of pre-exposure CMP on transmission, with readouts including nasal-wash titers, seroconversion, lung index, and tissue titers (EID₅₀). RT-qPCR was employed to quantify the mRNA expression levels of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6, in lung tissue, while Western blot analysis was performed to assess the expression and phosphorylation status of key proteins involved in the NF-κB signaling pathway. CMP suppressed viral replication in vitro within non-cytotoxic ranges, and pre-treatment—rather than co- or post-treatment—significantly reduced titers and cytopathic effect, consistent with effects at pre-entry steps and/or host priming. In vivo, pre-exposure CMP lowered nasal shedding, reduced aerosol transmission (3/6 seroconverted vs. 6/6 controls), decreased lung indices, and diminished tissue viral loads; IAV was undetectable in trachea at 7 days post-infection in pre-exposed animals, and nasal-turbinate titers declined relative to infection controls. Moreover, during in vivo treatment in mice, CMP significantly suppressed the levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6) in lung tissue. This effect was mechanistically associated with CMP-mediated regulation of the NF-κB signaling pathway, leading to attenuation of inflammatory responses. These data indicate that CMP combines a favorable in vitro safety and efficacy profile with inhibition of airborne spread in vivo, supporting further mechanistic, pharmacokinetic, and fractionation studies toward translational development. Full article

Cassava (Manihot esculenta) is a staple crop in sub-Saharan Africa threatened by several viral diseases. Here, we describe the genome sequence of a novel bipartite cheravirus (family Secoviridae) infecting cassava in the Democratic Republic of Congo and Tanzania. We designate the new virus “cassava Congo cheravirus”. Each RNA segment encodes a single polyprotein (P1 and P2 for RNA1 and RNA2, respectively), embedded with various putative cleavage sites (six and three in P1 and P2, respectively), consistent with members of the genus Cheravirus. We note two new features in the P1: (i) the presence of two domains, X1 and X2, upstream of the putative helicase region, which we also predict in other cheraviruses and (ii) the presence of a Maf/HAM1-like inosine triphosphatase (ITPase) domain, a rare motif among viruses only previously detected in three potyviruses and a torradovirus, all of which infect plants from the Euphorbia family. Phylogenetic analyses placed the virus firmly within the genus Cheravirus, with amino acid identities in the Pro-Pol and coat protein regions well below existing ICTV species thresholds, supporting its classification as a virus belonging to a new species in the Cheravirus genus. Spatially distinct isolates from Bas-Congo, South-Kivu, and Tanzania form three genetic clusters, with evidence of recombination in both RNA segments. These results expand the known diversity of cassava viruses and suggest possible adaptation to the cassava host via ITPase acquisition. Full article

Transmissible gastroenteritis (TGE), caused by the TGE virus (TGEV), is a highly contagious enteric disease characterized by vomiting, dehydration, and watery diarrhea. It mainly endangers piglets within two weeks of age, with a 100% mortality rate, inflicting severe economic losses on the global swine industry. Since enteric tropism of the virus and mucosa serves as the first line of defense against viral invasion, an oral vaccine inducing sufficient secretory immunoglobulin A (SIgA) antibodies in animals should be developed. Being a generally recognized as safe (GRAS) microorganism, Bacillus subtilis can form endospores under extreme environmental conditions, which confer resistance to the hostile gastric environment and have been widely employed as delivery vehicles for oral vaccines owing to their immunoadjuvant activity and non-specific antidiarrheal effects. In this study, the AD antigenic epitope of the TGEV S protein was selected as the immunogen. The mature peptide of the B subunit of the heat-labile enterotoxin from enterotoxigenic Escherichia coli served as a mucosal adjuvant, and B. subtilis WB800N was used as the delivery host to construct the recombinant strain pHT43-LTB-AD/WB800N. After confirming the successful expression of the target protein, oral immunization was performed using mice as a model. The results demonstrated that this recombinant strain induced robust mucosal, humoral, and cellular immunity, along with considerable levels of neutralizing antibodies. These findings indicate that recombinant B. subtilis could serve as an oral vaccine candidate to combat TGEV infections. Full article

Foot-and-mouth disease virus (FMDV) infection elicits sustained, high-level interleukin-10 (IL-10) secretion in cattle and pigs, which correlates with lymphopenia and immunosuppression. We previously showed that macrophages are the principal source of IL-10 during FMDV infection in mice, but the viral trigger and host pathways remained unknown. In the present study, we examined whether the FMDV structural protein VP3 regulates IL-10 expression. To this end, a eukaryotic VP3 expression vector was transfected into porcine alveolar macrophages (3D4/21 cells), and IL-10 expression together with related signaling pathways was interrogated by qRT-PCR, ELISA, Western blot, co-immunoprecipitation (Co-IP), confocal microscopy, and luciferase reporter assays. The results showed that VP3 significantly increased IL-10 mRNA and protein levels (p < 0.001) in a time-dependent manner. Mechanistically, VP3 promoted phosphorylation of PI3K, AKT, and mTOR; this effect was abolished by the PI3K inhibitor LY294002, which also abrogated VP3-induced IL-10 secretion (p < 0.05). Furthermore, VP3 upregulated mRNA expression of STAT3, ATF1, and CREB (p < 0.05) and enhanced IL-10 promoter activity. The STAT3 inhibitor Stattic reduced IL-10 secretion by 22% (p < 0.05). Co-IP and confocal microscopy confirmed direct binding of VP3 to PI3K in the cytoplasm. In conclusion, FMDV VP3 induces IL-10 overexpression by directly activating the PI3K/AKT-mTOR signaling pathway, thereby elucidating a key mechanism of FMDV-induced immunosuppression. Full article

Epstein-Barr virus (EBV) infection shows the strongest causative association with multiple sclerosis (MS), but its contribution to disease progression and the mechanisms allowing for viral persistence in the MS brain are still elusive. Studies in post-mortem MS brain tissue indicate an ongoing yet ineffective antiviral immune reaction in advanced stages of the disease. EBV has evolved strategies to evade immune recognition and clearance by the host immune system during both the latency and lytic phase of its life cycle. Recent evidence demonstrates that cells expressing EBV latent membrane protein (LMP) 2A exploit the PD-1/PDL1 inhibitory immune checkpoint to escape immune surveillance and maintain a persistent latent infection in the MS brain. This study investigated whether the virus also utilizes this inhibitory mechanism during other phases of the viral life cycle. By using multiple immunostainings on highly inflamed MS brain tissues containing meningeal tertiary lymphoid structures (TLSs), we analyzed PD-L1 expression on EBV-infected cells expressing EBNA2, five EBV lytic gene products, BZLF1, BHRF1, BMRF1, BALF2, and gp350/220, as well as on follicular dendritic cells within the TLSs. This is the first study describing in secondary progressive MS brain tissue the expression and the cellular and tissue distribution of PD-L1 on EBV-infected cells being in different stages of the viral life cycle, and confirms the meningeal TLSs as immune-permissive habitats favoring the maintenance of an intracerebral EBV reservoir. Full article