Search Results (415)

Highly pathogenic avian influenza (HPAI) is a lethal disease of poultry that has recently spilled over into mammals, including dairy cattle and humans, heightening concerns for livestock health, food security, and pandemic emergence. While vaccines that induce neutralizing antibodies against hemagglutinin and neuraminidase provide strain-specific protection, durable cross-subtype immunity requires T-cell responses targeting conserved internal antigens such as nucleoprotein (NP). To leverage these conserved targets, we utilized a previously engineered mosaic nucleoprotein (MNP) incorporating T-cell epitopes from thousands of influenza A virus (IAV) strains, conferring broad protection against epidemic (H3N2) and pandemic (H1N1) IAV in mice. Here, we tested whether precision adjuvancy could differentially imprint adaptive immunity to MNP in cattle. Combination formulations paired the carbomer-based nano-emulsion Adjuplex (ADJ) with either a STING agonist (cyclic dinucleotides; CdN) or a TLR4 agonist (glucopyranosyl lipid A; GLA) to program distinct inflammatory milieus. Both formulations elicited circulating IFN-γ–producing T cell responses and NP-specific antibodies in serum and milk. However, STING activation via CdN generated more potent and consistent cellular and humoral immunity than TLR4 engagement. These data demonstrate that selective activation of innate sensing pathways functionally imprints adaptive immune magnitude and quality in a large animal host. By advancing a broadly protective, T-cell-focused vaccine strategy in cattle, this work supports a One Health framework to mitigate H5N1 transmission risk at the human–animal interface. Full article

Segmented and non-segmented negative-strand RNA viruses share the same general pathway for genome transcription, which generates messenger RNA, and genome replication which duplicates the viral RNA. These processes are performed by the viral polymerase and necessitate the viral RNA to be coated by a non-covalent polymer of nucleoproteins known as nucleocapsid. The non-segmented negative-strand RNA viruses (nsNSVs) have rigid nucleocapsids covering the entire tightly bound genome and require a phosphoprotein cofactor for proper replication and transcription by the polymerase, while the segmented negative-strand RNA viruses (sNSVs) have very flexible nucleocapsids with only few nucleotides tightly bound to each nucleoprotein, and their viral RNA genome ends are directly bound to the polymerase. We discuss here how the differences in RNA binding are likely to be crucial for proper replication and transcription in both nsNSVs and sNSVs. Full article

Background. The highly mutable influenza virus causes severe annual infections worldwide and results in substantial socioeconomic losses. The spread of infection could be effectively controlled by cross-protective vaccines and universal diagnostic test systems based on the nucleoprotein (NP) as one of the most conserved viral antigens. However, NP also undergoes slow evolutionary changes, and little is known about the influence of these mutations on its antigenicity and immunogenicity. Methods. We expressed the full-length recombinant 6xHis-tagged NPs of ten evolutionary distant influenza A strains of different subtypes in E. coli BL21(DE3) cells and purified these proteins by immobilized metal affinity chromatography. The obtained antigens were identified by mass spectrometry and serological methods. NPs served as antigens for three immunizations of BALB/c mice (15 µg/animal at 14-day interval) and as capturing proteins in ELISA at 2 µg/mL, in order to study the effect of adaptive mutations on the antigenic and immunogenic properties of NPs. Results. A pronounced cross-reactivity of anti-NP antibodies induced in mice by immunization with different NPs was revealed. At the same time, we observed the differences in the humoral immunogenicity of NP, which are in line with the accumulation of evolutionarily driven NP mutations. In general, antibody affinity to heterologous NPs was reduced, indicating the differences in the specificity of anti-NP immunoglobulins, which may be caused by evolutionarily determined variability of immunogenic epitopes leading to the emergence of escape mutations. Conclusions. Overall, our results reflect the slightly evolving nature of the NP antigen, which influences the specificity spectrum of anti-NP antibodies and should be considered as a limitation for the development of NP-based cross-protective vaccines and test systems. Full article

Background: Crimean-Congo hemorrhagic fever (CCHF) is a severe tick-borne viral disease with a high fatality rate, and no licensed vaccines are currently available. The nucleoprotein (NP) of the Crimean-Congo hemorrhagic fever virus (CCHFV) plays a critical role in viral replication and immune recognition, making it a promising target for vaccine development. This study aimed to design and evaluate a multiepitope recombinant DNA vaccine targeting the NP of CCHFV. Methods: Cytotoxic T lymphocyte (CTL) epitopes from the NP were predicted via immunoinformatics approaches and systematically assessed for antigenicity, allergenicity, toxicity, hydrophobicity, and global population coverage. The selected epitopes were incorporated into four DNA vaccine constructs driven by a cytomegalovirus promoter, adjuvanted with human β-defensin 3 (hBD3), and fused to the reporter protein mRuby3. The constructs were evaluated in vitro using a fluorescent reporter system designed to provide a readout of TCR signaling upon the co-culture of T lymphocytes with differentiated monocytic cells expressing antigens. In vivo immunogenicity and protective efficacy were assessed in BALB/c (exploratory pilot) and IFNAR^−/− mice, a highly susceptible model for viral infection. Cytokine responses were measured to assess immunogenicity. Results: In vitro assays showed predominantly antigen-independent T-cell activation, suggesting that nonspecific stimulation inherent to the reporter co-culture system likely obscured the detection of antigen-specific TCR signaling. In vivo analyses in BALB/c mice revealed that the constructs elicited only modest systemic cytokine profiles while CCHFV-specific IgG and IFN-γ secretion remained undetectable, indicating that antigen-specific T-cell and antibody responses were limited. In the IFNAR^−/− challenge model, several peptide groups achieved significant 2–3 log reductions in tissue viral RNA and infectious titers (p < 0.05 vs. sham). However, the observed viral modulations were insufficient to reach the protective threshold and did not translate to a survival benefit (0%). Conclusion: Despite a rational in silico foundation, the multiepitope DNA vaccine constructs demonstrated limitations in inducing potent, antigen-specific immunity across both mouse models. The lack of antigen-specific responses indicates limitations in epitope selection, construct design, and delivery strategies, requiring optimization of next-generation epitope-based vaccines. These findings highlight the complexity of translating computational epitope predictions into functional vaccines, and provide benchmark data as a framework to guide future optimizations. Full article

Background/Objectives: The main goal of this study is to identify predictors associated with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) seropositivity in children, including demographics, history of coronavirus disease 2019 (COVID-19) infection of the child and the household members, prevention practices, and maternal vaccination. Methods: This retrospective cross-sectional study within the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH)/MeKiTamara cohort included 300 mother-child dyads recruited in Paramaribo and Nickerie, Suriname (February–April 2023). The total immunoglobulin G (IgG) anti-spike domain 1 (S1) and anti-nucleoprotein (NP) were quantified in dried blood spot (DBS) eluates from children using indirect enzyme-linked immunosorbent assays (ELISAs). Demographic information, COVID-19 prevention measures, history of viral infection of the child and the household members, and COVID-19 vaccination questionnaire data were recorded. Predictors of SARS-CoV-2 seroprevalence were determined using binary logistic regression. Results: Among 278 seropositive children in 2023, 73.4% were in the 5–6-year-old age group, 54.7% were female, 36.3% were of Asian descent, and 69.8% were recruited in Paramaribo. Seroprevalence increased from 33.8% in 2021–2022 to 93.3% in 2023, with a mean follow-up of 21.5 months. Of the 100 children previously tested by Polymerase Chain Reaction (PCR) or antigen test, 25 had confirmed COVID-19, as reported by mothers. Children from unvaccinated mothers were 6.11 times more likely to be seropositive (p = 0.022). Conclusions: This study shows a significant increase in SARS-CoV-2 seropositivity in Surinamese children aged 3–6 years between collection periods, indicating multiple exposures. Future public health interventions and policies should account for maternal vaccination status to reduce children’s exposure to COVID-19 during future outbreaks. Full article

Hexavalent chromium [Cr(VI)] is a lung carcinogen. Central to its carcinogenic mechanism are Cr(VI)-induced DNA double strand breaks and chromosome instability. While breaks are usually repaired in healthy cells, Cr(VI) inhibits homologous recombination repair by targeting RAD51. RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3) are responsible for RAD51 loading and the stabilization of nucleoprotein filaments necessary for DNA strand exchange and repair. This study aimed to investigate the effects of Cr(VI) exposure on RAD51 paralogs. WTHBF-6 cells, a human lung cell line, were exposed to various environmentally and occupationally relevant concentrations of zinc chromate for acute (24 h) and prolonged (120 h) exposure times. After exposure to Cr(VI), we collected RNA for sequencing and assessed the ability of DNA repair proteins to form foci using immunofluorescence. Protein levels were measured with western blotting, RNA-Seq was validated with RT-qPCR, and protein–protein interactions were assessed with the Proximity Ligation Assay (PLA) assay. Cr(VI) transcriptionally repressed all RAD51 paralogs. Further functional analyses showed that Cr(VI) inhibited the foci formation of RAD51D after acute and prolonged exposures and of XRCC2 and XRCC3 after prolonged exposure. Cr(VI) also inhibited overall RAD51D protein expression, as well as its interaction with RAD51. These findings suggest that Cr(VI) inhibits all RAD51 paralogs, but RAD51D might be an early target of Cr(VI), leading to the loss of RAD51 filament formation and function and the overall inhibition of homologous recombination repair. Full article

Zoonotic diseases account for approximately one billion cases of illness and millions of deaths globally each year. Increasing contact between humans and competent wildlife hosts elevates the risk of zoonotic spillover. Synanthropic bird species are key players in the transmission of zoonotic pathogens, including flaviviruses such as West Nile virus (WNV) and influenza A viruses like Avian Influenza Virus (AIV). Active surveillance of sentinel birds inhabiting urban areas allows for early detection of emerging pathogens before they cause zoonotic outbreaks. Despite nesting in close proximity to humans, the role of the house martin (Delichon urbicum) in the circulation of flaviviruses and AIV remains poorly understood. Here, we analyzed the presence of antibodies against flaviviruses and AIV in a colony of house martins from southwestern Spain. In addition, we aimed to detect amplicons of the matrix and nucleoprotein genes of AIV using RT-qPCR. While none of the samples tested positive for AIV by RT-qPCR, we observed an AIV seroprevalence of 2.13% based on non-subtyped ELISA. Notably, this is the first report of AIV-seropositive D. urbicum individuals captured in Spain. Moreover, we detected a flavivirus-group seroprevalence of 24.34%, similar to rates reported in the same house martin population between 2018 and 2020, suggesting widespread circulation of flaviviruses within this synanthropic species. These results support the hypothesis that house martins may participate in the transmission of these viruses between wild bird populations and humans in urban environments. Full article

Clinical, experimental, and computational evidence of COVID-19 virulence and infectivity has been linked to SARS-CoV-2 shell disorder. A strong link was first discovered using an AI disorder-predicting tool, which detected an unusually hard (low disorder) outer shell among all SARS-CoV-2-related viruses but not in the 2003 SARS-CoV-1. This could account for the high infectivity found in SARS-CoV-2—but not in SARS-CoV-1—as it is believed that hard shells protect viral particles from the onslaught of the antimicrobial enzymes present in the respiratory system and saliva. As a result, much larger quantities of particles are shed by COVID-19 patients. Abnormally hard outer shells (M) are associated with burrowing animals, e.g., pangolins, and SARS-CoV-2 likely acquired these shells due to its long-term evolutionary interactions with pangolins. As for virulence, the inner shell of SARS-CoV-2 (N) has been found to exhibit lower disorder than that of SARS-CoV-1. This lower disorder is consistent with the fact that SARS-CoV-2 is less virulent than SARS-CoV-1, as higher disorder in the inner shell is associated with more efficient protein–protein binding during replication. The link between N/M disorder and virulence or infectivity falls under the umbrella of shell disorder models (SDMs), which can connect virulence, infectivity, and long COVID under one coherent concept. Evidence of the reliability and reproducibility of SDMs as applied to COVID-19 is examined. The hard M that is resisting the antimicrobial enzymes in the respiratory system can be extended to immunological enzymes, especially those found in phagocytes such as macrophages, which can therefore become a reservoir for the virus. Full article

Influenza A virus (IAV) infection constitutes a major public health threat. Severe influenza virus infection can induce intense inflammatory responses and lung injury, leading to serious clinical symptoms or even death. The utility of current anti-influenza drugs is often limited by side effects and the emergence of drug-resistant strains. Based on the critical role of L-type voltage-gated calcium channels (L-VGCCs) in influenza virus replication, this study investigates the antiviral activity and mechanism of verapamil, a classic L-type calcium channel antagonist, against H1N1-UI182 virus. Verapamil, an L-type calcium channel blocker, is widely used in the treatment of cardiovascular diseases and has a well-established safety profile. Through molecular dynamics (MD) simulation and network pharmacology analysis, we predicted the stable binding mode of verapamil to the target protein (PDB id: 6JPA) and its potential multi-target network. In vitro, verapamil exhibited antiviral activity against H1N1-UI182 in MDCK cells, enhancing the survival rate of infected cells and reducing viral nucleoprotein (NP) expression. In a lethal H1N1-UI182 infection mouse model, verapamil treatment markedly improved survival rates, alleviated weight loss and lung pathological damage, exhibiting a dose-dependent protective effect. Lung tissue analysis showed that verapamil effectively reduced the lung index and viral load, suppressed the activation of the Nuclear factor kappa B (NF-κB) signaling pathway, and decreased the expression of key inflammatory factors, thereby mitigating the cytokine storm. A comparison of administration regimens indicated that pre-treatment yielded optimal efficacy, suggesting verapamil acts primarily during the early stage of the viral life cycle. This study systematically elucidates that verapamil exerts antiviral and immunomodulatory effects by regulating the NF-κB pathway. Network pharmacology analysis suggested the potential involvement of multiple targets and pathways, including EGFR, SRC, and phospholipase D signaling, providing hypotheses for future mechanistic investigation. This paper supports a drug repurposing strategy against drug-resistant influenza viruses and highlights its significant potential for clinical translation. Full article

Highly pathogenic influenza A viruses of the H5 subtype continue to diversify worldwide through mutation and genetic reassortment, generating novel variants with unpredictable consequences under the One Health approach. Between 2024 and 2025, five outbreaks of avian influenza A viruses were detected in backyard poultry across Michoacán, Estado de México, and Ciudad de México. We conducted molecular and genetic characterization of five highly pathogenic H5N2 viruses isolated from these events. All cases tested positive for influenza A virus and the H5 hemagglutinin, exhibiting high pathogenicity with intravenous pathogenicity index values ranging from 2.88 to 3.0. Whole-genome sequencing revealed novel reassortants containing hemagglutinin from Eurasian H5N1 clade 2.3.4.4b and neuraminidase from the endemic Mexican H5N2 lineage. The viral genome of the isolate from Michoacán contained six segments derived from Eurasian H5N1 viruses introduced into North America in 2021–2022, while nucleoprotein and neuraminidase originated from Mexican H5N2 viruses. In contrast, viruses from Estado de México and Ciudad de México contained five H5N1-derived segments and incorporated polymerase basic protein 1, nucleoprotein, and neuraminidase from low-pathogenic H5N2 viruses circulating in 2024. Phylogenetic analyses confirmed the emergence of a distinct H5N2 Mexican sublineage, providing evidence of active viral reassortment and local evolutionary processes in Mexico. Full article

Influenza’s pandemic threat is driven by antigenic drift, which limits the efficacy of conventional vaccines. To address this challenge, we established a clinical serum-anchored computational design pipeline for a broad-spectrum multi-epitope mRNA vaccine (MEMV), bridging the gap between pure in silico design and clinical applicability. Using 36 longitudinal sera (d0/d28/d365) from 12 well-characterized human cohorts (6 vaccine recipients and 6 influenza patients) and high-density antibody-peptide microarrays, we empirically identified 12 immunodominant B-cell linear epitopes from the nucleoprotein (NP) of influenza A (H1N1/H3N2) and B viruses. These experimentally validated epitopes were combined with in silico-predicted conserved helper T-lymphocyte (HTL)/cytotoxic T-lymphocyte (CTL) epitopes (from NP/HA/NA) to construct MEMVs candidates, ensuring high antigenicity, non-toxicity, and 95.63% global HLA coverage. Molecular docking and 100 ns molecular dynamics (MD) simulations confirmed favorable conformational compatibility between MEMVs and Toll-like receptor 3 (TLR3) in silico immunization via C-ImmSim predicted robust B/T-cell responses and protective cytokine (IFN-γ/IL-10) production. Collectively, this pipeline shortens the preliminary design cycle for influenza vaccines, provides a standard epitope-combination strategy, and offers direct targets for follow-up in vitro/in vivo experiments. Full article

Influenza A viruses remain a major public health threat due to their high mutation rates, antigenic variability, and the emergence of resistance to current antivirals, underscoring the need for novel therapeutic options. Natural compounds rich in polyphenols and flavonoids have attracted increasing attention as potential broad-spectrum antiviral agents. In this study, the activity of Rhus coriaria L. water extract against Influenza A virus in BEAS-2B human bronchial epithelial cells was investigated. Cell viability assay identified non-cytotoxic concentrations, up to 0.1 mg/mL, which were used in infection experiments. Viral replication was assessed at multiple levels by quantitative real-time PCR, western blotting, immunofluorescence and tissue culture infectious dose 50% (TCID₅₀). Treatment with R. coriaria extract resulted in a dose-dependent and statistically significant reduction of viral load. The extract decreased mRNA levels of Hemagglutin (HA), Neuraminidase (NA) and Matrix protein 2 (M2). Consistently, western blot analysis showed a decrease in major viral proteins HA, Nucleoprotein (NP), Matrix protein 1 (M1) and Polymerase Acidic protein (PA). Confocal images revealed a marked reduction in HA and PA signals, results that are statistically significant according to quantitative fluorescence evaluation. The convergence of results obtained through independent methodologies at both the transcriptional and protein levels highlight the robustness of the findings. These data provide the experimental evidence that Rhus coriaria interferes with influenza A virus replication in airway epithelial cells and support its further investigation as a promising phytochemical platform for the development of novel anti-influenza strategies. Full article

Globally, 24 measles virus genotypes have been detected, and these genotypes have been classified into eight clades based on 450 nucleotides of the C-terminal region of the nucleoprotein gene. Genotype B3 is predominant in Africa, but there are limited data from Tanzania since the introduction of the second dose of measles-containing vaccine in 2014. A total of 129 nasopharyngeal samples and corresponding sera were collected during measles outbreaks between 2022 and 2024. Viral RNA was extracted from nasopharyngeal swabs prior to RT-qPCR and sequencing of a 450-nucleotide segment of the nucleoprotein (N) gene. Out of 129 nasopharyngeal samples, 73 (56%) were successfully amplified and identified as endemic measles virus genotype B3. Nine distinct sequence identifiers were detected, with seven reported for the first time in the MeaNS database. All the Tanzanian B3 sequences were closely related and clustered with genotype B3, similar to those reported from Kenya, Ethiopia, Rwanda, Uganda, Burundi, and South Africa. On multivariate analysis, only inpatient admission status (p = 0.014) and positive measles IgM (p = 0.003) were found to be associated with positive measles RT-qPCR. Our results indicate that genotype B3 remains endemic in Tanzania and is closely related to other genotype B3 reported globally, indicating its high stability and transmissibility. Full article

Seals are keystone animals in the Arctic and a valuable resource for Indigenous communities, but their virome is poorly understood. Through a preliminary investigation of the virome of seven North Atlantic bearded seals (Erignathus barbatus) from northwest Newfoundland, Canada, we discovered a new member of the Paramyxoviridae, a family including important animal pathogens. The complete coding genome sequence (15,898 nt) of the novel paramyxovirus, which we named bearded seal-associated paramyxovirus 1 (BSAPV-1), encoded five core paramyxoviral proteins—nucleoprotein, matrix, fusion, hemagglutinin-neuraminidase, and polymerase—and three proteins with no identifiable homologues that may represent the phosphoprotein, a small hydrophobic protein, and a transmembrane protein. Phylogenetic analysis, including BSAPV-1 and all 153 currently known paramyxoviral species, positioned the novel virus in a long-branched clade with Wenzhou Pacific spadenose shark paramyxovirus (Skoliovirinae, Scoliodonvirus scoliodontis), its closest relative (pairwise identity of the L protein: 30.1%). According to ICTV criteria, BSAPV-1 is likely the first member of a novel paramyxoviral subfamily. As the virus was found in combined tracheal/fecal swabs of a single animal, we could not conclude whether this is a seal virus or a virus associated with seal food. This study expands our knowledge about marine paramyxoviruses, and future studies should investigate BSAPV-1 ecology, spread, and host spectrum. Full article

The reliance on unstable hydrogen peroxide (H₂O₂) adversely affects the robustness and simplicity of chemiluminescence (CL)-based immunoassays. We report a novel external H₂O₂-free Fenton CL system integrated into a highly sensitive non-enzymatic immunoassay for the detection of SARS-CoV-2 nucleoprotein, utilizing cuprous–polyethylenimine–lipoic acid nanoflowers (Cu(I)-PEI-LA-Ab NF) as a non-enzymatic tag. The signaling polymer (PEI-LA) was synthesized via EDC/NHS coupling, which conjugated approximately 550 LA units to the PEI backbone. This polymer formed antibody-conjugated NF with various metal ions, and the Cu(I)-based variant was selected for its intense and sustained CL with luminol. The mechanism relies on an in situ Fenton reaction, in which dissolved oxygen is reduced by Cu(I) to H₂O₂, which reacts with oxidized Cu(II), producing hydroxyl radicals that oxidize luminol. Direct calibration of the SARS-CoV-2 nucleoprotein fixed on microplate wells demonstrated excellent linearity in the range of 0.01–3.13 ng/mL (LOD = 3 pg/mL). In a final competitive immunoassay format for samples spiked with the antigen, a decreasing CL signal that correlated with increasing antigen concentration was obtained in the range of 0.1–20.0 ng/mL, achieving excellent recoveries that were favorable compared with those of the sandwich ELISA kit, establishing this H₂O₂-independent platform as a powerful and robust tool for clinical diagnostics. Full article