Search Results (1,558)

The SARS-CoV-2 spike protein has been shown to activate Toll-like receptor 4 (TLR4), yet the precise molecular structures driving recognition and subsequent activation remain poorly defined. Here, we present in silico structural alignments and molecular docking simulations indicating potential spatial compatibility between the wild-type SARS-CoV-2 HR1HR2 fusion core and the human TLR4/MD-2 heterodimer. The computational models project candidate interfaces involving salt bridges, as well as polar and non-polar interactions, with both TLR4 and MD-2 dimerization partners, suggesting a theoretical topology compatible with the dimerization of two TLR4/MD-2 heterocomplexes. Notably, similar structural compatibility was modeled for related class I fusion proteins from other highly pathogenic viruses, including SARS-CoV, MERS-CoV, influenza viruses A, B, and C, respiratory syncytial virus (RSV), and partially Ebola virus. These findings offer an exploratory computational hypothesis regarding viral–host interactions with the host innate immune system, which can trigger immune recognition or detrimental hyperactivation. Full article

H3N2 subtype avian influenza virus (AIV) is prevalent in poultry and wild birds and typically causes asymptomatic or mild respiratory infections. However, genetic reassortment between H3N2 and other AIV subtypes generates novel strains capable of crossing the species barrier, posing a threat to both poultry and public health. In this study, nine H3N2 AIVs were isolated from ducks in live poultry markets (LPMs) in Guangxi, southern China, during 2022–2024. Phylogenetic analysis revealed that all eight gene segments of the nine isolates were clustered within the Eurasian lineage, with internal genes derived from multiple subtypes, including H1, H2, H3, H4, H5, H6, H7, and H9. These findings indicate complex gene reassortment of H3N2 AIVs in Guangxi. Importantly, the PB2 genes of certain isolates were closely related to those of highly pathogenic H5 subtype viruses, suggesting that H3N2 AIVs may contribute internal genes to H5 viruses. Three representative isolates (LZD44, NND98, and NND100) were assessed for pathogenicity in SPF chickens and mice. All three strains successfully replicated in the respiratory tissues of both species. Notably, the LZD44 virus, which harbored the mammalian-adaptive mutations PB2-MVV and NP-I353V, presented significantly higher virulence in chickens and mice than the other two strains. These results demonstrate that H3N2 subtype AIVs are capable of replicating in certain tissues of chickens and mice without prior adaptation, underscoring a potential risk for cross-species transmission. Consequently, sustained surveillance of H3N2 subtype AIVs is essential to prevent the spillover of novel recombinants into the human population. Full article

Ticks are important arthropod vectors that transmit various pathogens to humans, livestock, and wildlife, thereby contributing significantly to the global burden of vector-borne diseases. The tick microbiome, consisting of bacteria, viruses, protozoa, and other microorganisms, plays a crucial role in pathogen transmission dynamics and the emergence of new zoonotic diseases. This review examines the characteristics of tick vectors, the composition and dynamics of tick-associated microbiomes, and their implications for zoonotic disease transmission. We analyze current knowledge of tick-borne pathogens, including Borrelia burgdorferi sensu lato, Rickettsia species, Anaplasma species, and Coxiella species, and highlight the potential for microbiome constituents to serve as reservoirs for emerging pathogens. The complex interactions between tick hosts, their microbiomes, and vertebrate hosts create opportunities for pathogen evolution and interspecies transmission. Recent advances in molecular techniques have revealed previously unknown microbial diversity within tick populations, suggesting that many potential zoonotic pathogens remain undiscovered. We discuss future research directions, including field screening methodologies for pathogen detection, microbiome-based risk assessment approaches, and the development of novel prevention strategies, including tick vaccines. Full article

Viruses cause a great number of infectious diseases with medical, veterinary, agricultural, social and economic impact. Their unique mechanisms to spread, overcome and resist the existing countermeasures require innovative and smart antiviral strategies such as the effective disinfection of enclosed environments with ensured broad-spectrum efficacy and minimized risks associated with handling liquid biocides. Formic acid (FA) is a well-established natural acaricide used in beehives with an antiviral potential; however, its application in a liquid form is hindered by severe corrosiveness and rapid, uncontrolled evaporation. This study describes a novel formulation of FA, using a cryogel carrier for achieving a vapor-phase inactivation of viruses, thus eliminating the need for direct contact between the disinfectant and the pathogen. Firstly, a poly(N-isopropylacrylamide) (PNIPAm) cryogel was synthesized by a procedure involving cryogenic treatment, photochemical crosslinking, and freeze-drying, and then the cryogel was swollen with 65% FA or _ddH₂O as a control. After an exposure of a panel of animal and human viruses to FA, evaporated by the polymer carrier for time intervals between 15 min and 12 h, they were neutralized completely as follows: Poliovirus (PV) as a surrogate for major bee viral pathogens for 60 min by 5.1 ∆lg; Feline calicivirus (FCV) for 60 min by 5.3 ∆lg; Adenovirus 5 (AdV5) for 12 h by 4.0 ∆lg; and Influenza virus A (IAV) for 15 min by 5.1 ∆lg. Results were recorded after titration, 48–72 h incubation, cytopathic effect estimation and NR uptake assay. Our results suggest that 65% FA, when delivered via the PNIPAm cryogel matrix, acts as a powerful agent for fumigation-like disinfection. This “dry” delivery strategy offers significant practical advantages: it eliminates the need for open liquid containers, prevents spill-related hazards, and provides an alternative for controlled, long-term release of active vapors. Full article

Under a One Health framework, viruses of veterinary and zoonotic importance pose significant threats to animal and human health, food security, and livelihoods, particularly in regions with intense human–animal interactions. In West Africa, despite recent advances in surveillance programs, important gaps remain in understanding viral diversity and cross-species transmission at wildlife–livestock interfaces. We conducted metagenomic surveillance to characterize viruses circulating across livestock, domestic animals, and wildlife in rural Ghana in 165 animals sampled across five regions. Viral RNA from serum and tissue samples was sequenced with the Illumina platform, and genomes were de novo assembled with MEGAHIT. Phylogenetic relationships were reconstructed using Bayesian approaches. We report the first genomic sequences of porcine parvovirus 3, canine parvovirus, rotavirus A genotype R16, and bovine hepacivirus subtype B from Ghana in over a decade. Phylogenetic analyses revealed intercontinental linkages between Africa and Europe for parvoviruses, persistence of hepacivirus lineages, and evidence of cross-species transmission for rotavirus. Notably, detection in apparently healthy animals highlights underrecognized circulation, gaps in vaccination effectiveness, trade-related biosecurity vulnerabilities, and the role of wildlife in viral maintenance and transmission. Our findings reveal dynamic viral diversity and connectivity across animal populations and ecological interfaces, emphasizing the fluid and interconnected nature of pathogen circulation within One Health systems. By integrating metagenomics and phylogenetics, this study provides a scalable framework for enhancing surveillance capacity, enabling the early detection of emerging threats and informing targeted strategies to mitigate zoonotic and economically important viral diseases in West Africa. Full article

Background/Objectives: Respiratory syncytial virus (RSV), human metapneumovirus (hMPV), and parainfluenza virus type 3 (PIV3) are leading causes of acute respiratory infections in children and the elderly, yet no licensed T-cell vaccines are available. This study aimed to develop multivalent T-cell vaccine candidates against these pathogens using a live attenuated influenza virus (LAIV) vector platform. Methods: Conserved F, N, and M proteins of RSV, hMPV, and PIV3 were identified through multiple sequence alignments. Fragments enriched with experimentally confirmed and predicted T-cell epitopes were selected using the IEDB and NetMHCpan servers. These fragments were assembled into polyepitope immunogenic cassettes, and their selected order was determined by thermodynamic analysis of mRNA secondary structures using the RNAfold Web Server. The selected cassettes were cloned into the neuraminidase (NA) gene of a cold-adapted LAIV vector. Recombinant viruses were rescued by reverse genetics and assessed for replicative fitness in embryonated chicken eggs and MDCK cells, NA enzymatic activity and genetic stability upon serial passaging. Results: Four cassettes were designed for RSV, three for hMPV, and one for PIV3, all containing fragments with multiple T-cell epitopes. Three recombinant viruses of LAIV/RSV type and three of LAIV/hMPV type were successfully rescued, while attempts to recover the remaining recombinant viruses, i.e., LAIV/RSV and LAIV/PIV3, were not successful. All rescued recombinant viruses replicated to titers comparable to the parental LAIV strain and retained the full-length insert for at least eight passages in eggs. Importantly, NA enzymatic activity of the LAIV vector was not compromised by the insertion of the polyepitope T-cell cassettes. Conclusions: We developed a panel of recombinant T cell-based vaccine candidates against RSV and hMPV using the LAIV vector platform. These recombinant viruses encode conserved T-cell epitopes of the target viruses while retaining the biological properties of LAIV strains. Taken together, these characteristics warrant further evaluation of these recombinant viruses in appropriate relevant in vitro models to directly assess their immunogenicity in terms of stimulating a T-cell response against target pathogens. Full article

Bivalve mollusks efficiently bioaccumulate human enteric viruses, posing significant food safety risks. This study assessed the prevalence of Norovirus (NoV GI and NoV GII), Hepatitis A virus (HAV), and Hepatitis E virus (HEV) in 59 samples of live mussels (Mytilus galloprovincialis) collected from the Bulgarian Black Sea coast between July 2022 and July 2023. Viral detection was performed using one-step real-time reverse transcription-polymerase chain reaction (RT-qPCR) following ISO 15216-2 standards, with a mean extraction efficiency of 4.06%. Norovirus GII was the most prevalent pathogen, with detection peaks following intense rainfall events in July 2023. In contrast, all samples tested negative for HAV and HEV. The analysis showed no significant correlation between E. coli contamination levels and the presence of NoV (Mann–Whitney U test, p = 0.565). The viral RNA was detected in several samples that otherwise complied with regulatory bacterial standards for direct consumption (≤230 MPN/100 g). In conclusion, within the limitations of the evaluated sample size and the specific geographically unbalanced sampling design, NoV GII was the predominant genogroup detected. These results suggest that current bacterial indicators may be insufficient to ensure viral safety in these products. In this regard, national control authorities need to undertake timely policies and measures for better and adequate surveillance, control and prevention of viruses in the different parts of the food chain. Full article

Rodents and shrews are important reservoir hosts due to their close association with human activities and their role in carrying various zoonotic pathogens. Recently, meta-transcriptomic sequencing has become a powerful tool for surveilling and screening novel pathogens from wild animals. However, many of these studies focused only on the diversity and genetic evolution of viruses from wildlife, while ignoring non-viral pathogens such as bacterial and eukaryotic microorganisms. Here, we performed a comprehensive infectome analysis of 227 tissue samples collected from 42 rodents and 16 shrews across six cities of Guangdong Province, China. We identified 34 viral families, including 23 mammalian viruses. Phylogenetic analysis revealed a henipavirus from the kidneys of shrews closely related to the Langya virus with potential infection risks to humans. Additionally, two potential pathogenic bacteria and 12 eukaryotic pathogens from six genera were found, showing clearer organ tropism than viruses. Interestingly, a moderate positive abundance correlation between Usmuvirus newyorkense and Trichinella suggested a potential virus–parasite association. We used machine learning models to evaluate the zoonotic potential of the obtained viruses, which indicated that 15 of 23 viral species were high risk for human infection. These findings provide important insight into the substantial zoonotic threat posed by pathogens circulating in wild small mammals in southern China and highlight the necessity for persistent wildlife pathogen surveillance. Full article

The innate immune system, particularly the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) signaling pathway, is a major early defense barrier against influenza A virus infection. However, excessive immune responses can trigger lethal cytokine storms and severe immune-mediated pathology. In this study, we performed a genome-wide CRISPR/dCas9 gene activation screen in human lung epithelial (A549) cells by using an A/Puerto Rico/8/1934 (H1N1) reporter virus, and identified the ubiquitin-specific protease USP17L13 as a novel negative regulator of innate immunity that promotes influenza virus replication. Overexpression of USP17L13 significantly enhanced the replication of multiple subtypes of influenza viruses in A549 cells, including a human pandemic H1N1 virus, seasonal H3N2 viruses, as well as a globally circulating clade, 2.3.4.4b, of the highly pathogenic avian H5N1 virus. Transcriptomic analysis demonstrated that USP17L13 suppresses host antiviral defenses by downregulating nuclear factor kappa B (NF-κB) signaling and arachidonic acid metabolism, while upregulating pathways associated with ribosomal translation and oxidative phosphorylation to facilitate viral production. Mechanistically, USP17L13 attenuates the host interferon (IFN) response by promoting the degradation of the key viral RNA sensors, RIG-I, and melanoma differentiation-associated protein 5 (MDA5). Further analysis revealed that USP17L13 is inducible by type I and type II interferons as well as inflammatory cytokines, suggesting that it may act as a negative-feedback regulator to limit excessive inflammation. Collectively, our findings identify USP17L13 as a previously unrecognized proviral host factor and provide new insight into how host deubiquitinases shape influenza virus-host interactions, with potential implications for host-directed approaches to controlling excessive inflammation during viral infection and improving influenza vaccine production. Full article

BK and JC Polyomaviruses (BKPyV and JCPyV) are ubiquitous human pathogens capable of establishing lifelong, asymptomatic persistence in the majority of the global population. While decades of research have focused on their lytic replication cycles and the development of severe diseases, such as polyomavirus-associated nephropathy (PVAN) caused by BKPyV and progressive multifocal leukoencephalopathy (PML) caused by JCPyV, their primary evolutionary strategy is one of persistence rather than pathogenesis. This review shifts the perspective from a replication-centric framework towards an evolutionary persistence model, detailing the multi-layered host and viral determinants that maintain the homeostatic balance. At the cellular level, viral genomes are restricted by chromatinization into minichromosomes and host S-phase licensing. These constraints are reinforced by innate immune sensing and adaptive T-cell and antibody responses that curtail systemic dissemination while permitting periodic, low-level urinary shedding, which is essential for horizontal transmission. In addition to these host barriers, the viruses utilize intrinsic regulatory mechanisms to prevent excessive replication and immune detection, including the stable archetype non-coding control region (NCCR), viral microRNAs that downregulate early gene expression, and the small t antigen (STAg). Finally, we address unresolved questions regarding the full spectrum of cellular reservoirs, the molecular triggers of reactivation, and the ecological factors shaping their transmission routes. Understanding these maintenance mechanisms is crucial for refining clinical interventions and managing the rare, devastating transitions from silent persistence to lytic disease. Full article

Infection by neurotropic alphaviruses such as the Eastern equine encephalitis virus (EEEV) causes extensive inflammation in the central nervous system and tissue damage, including disruption of the blood–brain barrier (BBB). Neuroinflammation and BBB disruption following infection are critical pathological considerations for the development of robust countermeasure strategies. Encephalitic disease resulting from EEEV infection currently lacks FDA-approved therapeutic intervention strategies, thus exposing a major capability gap in the ability to address the global health burden that could result from alphavirus infections. In this manuscript, we present a gravity-flow Neurovascular Unit (gNVU) model of the human BBB that may be used for modeling EEEV-induced neuropathology and evaluating countermeasures. The data generated using this model show that EEEV infection causes a time-dependent disruption of BBB integrity and increases the inflammatory load in a manner that correlates with an increase in the viral load. The data also show that the route of introduction of the pathogen has an impact on the pathology measured, with infection through the brain side eliciting a greater inflammatory outcome than infection through the vascular route. Overall, the included data support the utility of this organ-on-a-chip (OOC) platform of the human BBB in understanding encephalitic disease caused by neurotropic viruses and evaluation of therapeutic intervention strategies. Full article

The caliciviruses include important human and animal pathogens such as norovirus, sapovirus and feline calicivirus. Viral reverse genetics is performed to understand the fundamental biology of these viruses, as well as a potential route to generate live-attenuated vaccines. Calicivirus reverse genetics systems have typically relied on either the production of in vitro-transcribed RNA or plasmid-based rescue, either from a mammalian promoter or through supplementing with helper enzymes through means of a helper virus. Here, we present a novel system integrating vaccinia capping enzymes D1R and D12L encoded on plasmids as part of a system for murine norovirus (MNV) reverse genetics. The addition of D1R, D12L and T7 RNA polymerase-expressing plasmids increases the viral titres of rescued MNV in both BSR-T7 cells and transgenic BSR-T7 cells expressing murine CD300LF (BSR-T7^CD300LF), and viral protein abundance. When the murine norovirus receptor is expressed in BSR-T7^CD300LF, viral titres increased 100–1000-fold compared to standard BSR-T7 cells. This system offers a robust, increased throughput means of assessing viral mutants over parallel in vitro transcription and capping reactions for multiple mutants, without requiring a helper virus. Full article

Background and Objectives: The microbiome plays a pivotal role in male infertility, with distinct microbial species exerting both beneficial and deleterious effects on reproductive function. Sexually transmitted bacteria and several viruses, including human papillomavirus (HPV), have been identified in semen. This cross-sectional study aimed to examine the prevalence of single and co-infections of sexually transmitted bacteria (STB)—such as Chlamydia trachomatis, Mycoplasma spp., and Ureaplasma spp.—with various HPV subtypes in Greek male partners of infertile couples and to evaluate their potential impact on sperm parameters. In addition, the possible effect of cryopreservation on the maintenance of these pathogens was assessed. Materials and Methods: Eighty-two semen samples were initially collected from 82 individuals undergoing routine sperm analysis. In total, 80/82 (97.6%) participants proceeded to further analysis, as 2/82 (2.4%) were excluded due to poor DNA quality. Results: A total of 18/80 (22.5%) sperm samples tested positive for STB, with Ureaplasma spp. representing the most frequently detected pathogen. Co-infection of Ureaplasma spp. and Mycoplasma hominis was observed in 4/80 (5%) samples. Twelve samples (12/80, 15%) were positive for HPV, including low-risk (LR) and high-risk (HR) types, and HPV 16 was the predominant HR genotype. Notably, a co-infection of STB and HPV was not found in our specimens. STB-positive samples demonstrated significantly higher sperm concentration and improved progressive motility compared with STB-negative samples. HPV-positive samples exhibited lower sperm volume and concentration and increased non-progressive motility compared with HPV-negative samples. Following three months of cryopreservation, LR HPV and STB were no longer detectable, whereas HR HPV types remained detectable. Conclusions: These preliminary findings are interesting, as they could be useful for routine screening of HPV and STB in sperm samples preserved in sperm banks and highlight the need for future research. Full article

The recent SARS-CoV-2 pandemic—which had significant worldwide health, economic, and other effects—indicated the need to monitor zoonotic viruses with pandemic potential. The aim of this review is to assess bat-borne viruses as a potential pandemic risk, with a particular focus on Europe. The presence and activity of bats, as well as diseases emerging in humans in various regions of the world, point to their importance in the context of a possible outbreak of future epidemics. The rate of genetic change observed among viruses requires constant scrutiny on all continents, including Europe. Bats are a considerable source of many zoonotic viruses, including coronaviruses, filoviruses and paramyxoviruses. Among viruses associated with bats, RNA viruses are the dominant ones, characterized by high pathogenicity and often leading to interspecies transmission. The majority (about 80%) of RNA viruses were identified in bats from three families: Vespertilionidae, Rhinolophidae and Pteropodidae. Understanding how viruses are transmitted in the environment and the role of reservoir organisms and intermediate hosts is crucial to determining the level of epidemic risk. This review discuses viruses identified in bats globally, with a special focus on Europe, and evaluates their potential to cause epidemics. Full article

Since 2022, numerous H5N1 highly pathogenic avian influenza virus (HPAIV) detections have been reported in wild and domestic mammals in North America. Although H5N1 HPAIV detections in dogs are rare, hunting dogs that retrieve waterfowl are at increased exposure risk due to their physical contact with reservoirs (waterfowl) and contaminated environments. A cross-sectional survey of hunters was conducted during 2024 to characterize hunting procedures, disease prevention practices, and interactions between humans and their hunting dogs to identify potential risks for zoonotic disease transmission. Descriptive analysis (N = 112) indicated a majority of participants considered their hunting dog as part of the family (93.8%), and less than half considered their dog a pet (42.9%). Of the 112 individuals, 96.4% did not utilize personal protective equipment (PPE) when handling a sick dog and 81.3% did not use PPE when handling harvested birds. This research demonstrated complex, sustained physical and personal connections between individuals and their hunting dogs. Additional research utilizing a One Health approach is necessary to define H5N1 HPAIV risk factors in hunting dogs and the environment’s role in the transmission of viruses among wildlife and domestic animals. Understanding zoonotic disease transmission in these populations can inform approaches to mitigate viral exposure. Full article