Search Results (5,759)

The SARS-CoV-2 Omicron variant caused a global surge in COVID-19 cases following its emergence in November 2021, rapidly diversifying in the subsequent months. Although many studies have documented Omicron’s diversification, few have explored its impact on pediatric populations or the seasonality of other respiratory viruses in children. This study aims to investigate the diversity and circulation patterns of SARS-CoV-2 Omicron sublineages in pediatric patients in São Paulo, Brazil, and assess their co-circulation with other respiratory pathogens. Respiratory samples collected from patients under 18 years old across five hospitals between January 2022 and April 2023 were tested for different respiratory viruses using real-time RT-PCR. Whole-genome sequencing was performed on SARS-CoV-2-positive samples. Among the 7868 pediatric respiratory samples tested, 3902 were positive for viral pathogens. Respiratory Syncytial Virus accounted for the highest number of positive cases (n = 1248), exhibiting an atypical off-season peak in November 2022. SARS-CoV-2 was detected in 297 samples, of which 103 were sequenced. BA.1 and BA.5 sublineages had predominant genomic diversity and circulation time. These findings highlight the Omicron variant’s significant impact on the epidemiology and seasonal distribution of respiratory viruses in children, emphasizing the ongoing need for vaccination and robust surveillance efforts in pediatric populations. Full article

Avian viral arthritis (AVA), caused by avian reovirus (ARV), is a viral disease in chickens that has led to significant economic losses in the poultry industry. Recent studies have shown that traditional ARV vaccines based on the S1133 strain fail to protect against emerging ARV variants. In this study, we isolated and characterized three ARV strains (G4, YV, WF) from immunized chicken flocks with respiratory and arthritic symptoms. Genomic analysis revealed that the σC genes of G4, YV, and WF shared only 55.5%, 55.7%, and 58.7% sequence homology, respectively, with the S1133 strain. Phylogenetic analysis placed them in different branches, indicating they are variant strains. YV and WF belong to genotype III, and G4 falls into genotype VI. Whole genome analysis revealed gene segment reassortment among the variants. Pathogenicity testing in three-week-old SPF chickens showed that G4 (genotype VI) caused swelling of footpads, whereas WF (genotype III) did not. G4-infected chickens exhibited significantly higher viral loads in the thymus, lungs, spleen, and bursa of Fabricius than those in the WF-infected chickens, indicating viruses from different genotypes showed various pathogenesis. These results suggested an urgent need for new updates of vaccines against the variant ARVs, especially the genotype VI virus. Full article

Background/Objectives: This study explores the potential relationship between herpesvirus infections and the severity and progression of peri-implantitis. A secondary goal is to investigate whether a virus–bacteria interaction may contribute to differences in bone loss patterns between periodontitis and peri-implantitis. Methods: Biological samples, including blood, saliva, and peri-implant crevicular fluid, were collected for viral detection. Blood samples were processed at Queen Mary Laboratory in Bucharest, Romania, while saliva and peri-implant crevicular fluid samples were analyzed at the laboratory of ADD Laboral in Malden, the Netherlands. Sterile paper points were used to collect peri-implant crevicular fluid from the deepest peri-implant sites in 43 patients. A nearby tooth was sampled when present, with edentulous patients being the exception. Several clinical parameters were also considered, including implant and dentition status, smoking, gender, implant location, duration of functional loading, periodontal pocket depth (PPD), bleeding on probing (BoP), suppuration (SUP), and periodontal history. Results: Epstein–Barr virus (EBV) was detected in 30.2% of cases, Herpes virus (HSV) in 7.0%, and Cytomegalo virus (CMV) in 0%. EBV showed a moderate inverse correlation with probing depth (r = −0.48) in non-smokers with periodontal disease. Viral detection was highest on lingual and mesial surfaces. Peri-implantitis cases exhibited significantly deeper PPD, higher BoP (96.15%), and suppuration (96.15%) compared to healthy implants or teeth. Conclusions: An association was observed between the presence of Herpes viruses and increased peri-implantitis severity, suggesting a potential contributory role of viral pathogens in disease progression. Full article

Background/Objectives: Extracellular vesicles (EVs) are key mediators of intercellular communication and are implicated in the neuropathogenesis of HIV-associated brain injury (HABI). However, their direct effects on glial cells, particularly in the context of antiretroviral therapy (ART), remain incompletely understood. Methods: In this study, we investigated how EVs from naïve, Simian Immunodeficiency Virus (SIV)-infected, and SIV-infected ART-treated rhesus macaques impact primary mixed glial cultures. Results: Through multiple, sequential applications mimicking chronic exposure, we found that EVs from SIV-infected animals significantly reduced glial expansion and induced a simplified, reactive astrocyte morphology indicative of neuroinflammatory stress. In contrast, EVs from naïve animals supported glial health. EVs derived from ART-treated animals provided partial protection from SIV-induced effects, yet still suppressed glial proliferation and failed to fully restore normal morphology. Furthermore, cytokine profiling revealed that both SIV and SIV + ART EVs induced a sustained proinflammatory secretory phenotype, characterized by elevated IL-6, IL-8, and IFN-γ. Conclusions: Our findings demonstrate that systemically circulating EVs in SIV infection are potential drivers of glial dysfunction. The persistence of these pathogenic EV effects despite ART suggests a vesicle-mediated mechanism that may contribute to chronic neuroinflammation and cognitive impairment in virally suppressed individuals. Full article

Chicken anemia virus (CAV) targets the immune system of chickens, causing anemia and atrophy of the bone marrow and lymphoid organs, resulting in significant damage to poultry farming. From April 2024 to March 2025, a total of 359 liver samples were collected from broiler farms in 11 cities across Liaoning Province. CAV was detected using PCR, and 16 complete genome sequences of CAV isolates from different regions were analyzed through phylogenetic and recombination analyses. The overall CAV positivity rate was 13.9%, with spring identified as the peak season. Phylogenetic analysis and genotyping revealed that ten CAV strains clustered within subgroup C1, while the remaining six were distributed among subgroups C2 and C3, as well as Group D. Specific mutations were observed among the VP1 protein genotypes, including mutations previously associated with increased pathogenicity and transmission. One isolate, LN2511, was identified as a potential recombinant strain with its parents CAV-Shanxi7 and CAV-EG-13. During 2024–2025, CAV infection remained prevalent in Liaoning Province, with subtype C1 being the dominant genotype. Amino acid sequence analysis indicated the presence of highly pathogenic strains across the province. These findings fill a knowledge gap regarding CAV infection status and evolutionary trends in chicken populations in Liaoning, China. Full article

Greece is one of the countries in Europe most affected by West Nile virus (WNV), and since 2010, when the virus caused a large outbreak with 197 human neuroinvasive cases, outbreaks occur almost every year. Mosquito surveillance is an indirect sign of virus circulation; therefore, the purpose of the study was the molecular detection of WNV in 45,988 C. pipiens s.l. mosquitoes collected during 2024 in four Regions of Greece and the genetic characterization of the virus strains. WNV was detected in 41 of 1316 (3.12%) Culex spp. mosquito pools. Next-generation sequencing was applied to the WNV-positive samples that had a high viral load. All WNV sequences belong to Cluster B of the sub-lineage Europe WNV-2A presenting a temporal clustering. The WNV infection rates varied highly across the Regions, regional units and months, being higher in Thessaly and Central Macedonia Regions, especially in July and September. All mosquito pools were also tested for Usutu virus (USUV), and one pool was found positive, with sequence clustering into the EU-2 lineage. A subset of mosquitoes (737 pools) was tested for additional viruses, and bunya-like viruses were detected in 6 pools with sequences clustering into four distinct subclades. The prompt detection of pathogenic viruses is helpful for the design of control measures, while the detection of insect-specific viruses provides insights into viral diversity and evolution. Full article

Intestinal homeostasis disorders (IHDs), driven by food safety issues, pollution, and drug-resistant pathogens, threaten global health. Key factors in intestinal and metabolic diseases (like IBD, obesity, and liver disease) include barrier dysfunction, gut microbiota imbalance, and excessive immune activation. Transcription factors in intestinal epithelial cells are crucial regulators. ELF4, an ETS family transcription factor, plays vital roles in transcriptional regulation, impacting tumorigenesis, the DNA damage response, and the cell cycle. ELF4 deficiency exacerbates alcoholic liver disease (ALD). Significantly, ELF4 is a novel IFN-I transcription factor with antiviral capabilities. Its regulation of the type I IFN response offers new avenues for developing antiviral and anticancer strategies and managing IFN-induced autoimmune disorders. Thus, ELF4 emerges as a promising target for preventing and treating IHD-related diseases. Mechanistic studies could help identify diets or antimicrobials that activate intestinal ELF4 to combat pathogen/virus-induced intestinal diseases. Full article

Oz virus (OZV), an emerging negative-sense single-stranded RNA virus classified under the family Orthomyxoviridae and genus Thogotovirus, was first isolated from Amblyomma testudinarium ticks in Ehime Prefecture, Japan, in 2013. Moreover, a single fatal case in an elderly individual, suspected to be associated with OZV infection, was reported in Ibaraki Prefecture in 2023. Given these circumstances, this study was conducted to investigate the molecular epidemiology and seroepidemiology of OZV in Ibaraki Prefecture, Japan. From April to November 2023, a total of 2430 ticks were collected at 19 sites. The OZV RNA was detected in one A. testudinarium nymph. Additionally, among 934 wild boar serum samples collected between 2019 and 2023, one sample tested positive for OZV RNA. Neutralizing antibody assays revealed that 243 samples (26.0%) obtained from wild boars were seropositive, indicating widespread exposure among wild boars. Antibody prevalence and titers were highest in the central–western mountainous region, suggesting an active transmission hotspot. Sequence analysis of the OZV viral RNA detected from one tick sample and one wild boar serum revealed that a 212 bp fragment of segment 4 and a 261 bp fragment of segment 5 were 100% identical to a human-derived strain isolated in the same prefecture, suggesting the circulation of a single viral lineage within the local environment. These findings represent the first report demonstrating the circulation of OZV in the natural environment in Ibaraki Prefecture, implicating A. testudinarium as the principal vector and wild boars as a potential source of OZV infection These results suggest that OZV should be considered a potential emerging zoonotic pathogen. Further seroepidemiological studies among residents are warranted to assess the risk of human infection in the region. Full article

Early studies on the evolution of SARS-CoV-2 revealed mutations that favored host transmission of the virus and more efficient viral entry. However, cell-free virus spread is vulnerable to host-neutralizing antibodies. As population immunity developed, mutations that confer escape from neutralization were selected. Notably, cell syncytia formation wherein an infected cell fuses with a noninfected cell is a more efficient route of transmission that bypasses humoral immunity. Cell syncytia formation has been implicated in the pathogenicity of SARS-CoV-2 infection whilst compromising host transmission due to impaired whole virion release. Therefore, understanding the mechanisms of virus-mediated cell–cell fusion will aid in identifying and targeting more pathogenic strains of SARS-CoV-2. Whilst the general kinetics of cell–cell fusion have been known for decades, the specific mechanisms by which SARS-CoV-2 induces fusion are beginning to be elucidated. This is partially due to emergence of more reliable, high throughput methods of quantifying and comparing fusion efficiency in experimental models. Moreover, the ongoing inflammatory response and emerging health burden of long COVID may point to cell–cell fusion in the pathogenesis. In this review, we synthesize current understanding of SARS-CoV-2-mediated cell–cell fusion and its consequences on immune escape, viral persistence, and the innate immune response. Full article

Positive (+) sense RNA viruses include many important pathogens that exploit noncanonical translation mechanisms to express their genomes within the host cells. Unlike DNA or negative (−) sense RNA viruses, (+) sense RNA viruses can directly function as mRNAs, even though they lack typical features of host mRNAs, such as the 5′ cap structure required for canonical translation initiation. Instead, they exploit structured RNA elements to recruit host translational machinery without the 5′ cap, bypassing the canonical translation initiation mechanism. Prominent examples include internal ribosome entry sites (IRESs) and 3′ cap-independent translation enhancers (3′ CITEs). These RNA modules facilitate translation initiation by recruiting the ribosomal subunits, either directly or through initiation factors, and mediating long-range RNA-RNA interactions. Other regulatory motifs, such as frameshifting signals, allow the ribosome to shift reading frames to regulate protein output. All these RNA elements function through RNA-protein interactions and often utilize host and virus-encoded proteins to hijack the host’s translational apparatus. Over the past several years, various structural biology approaches, including biochemical and enzymatic probing, X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cryogenic electron microscopy (cryo-EM), have revealed the unique structural roles of these viral RNA elements and their protein complexes. Although a few structures of IRES and CITE domains have been solved through these methods, the structures of these RNA elements and their structure-function relationship have remained largely unknown. This review discusses the current understanding of translation-related RNA structures in (+) sense RNA viruses, the critical RNA-protein interactions they mediate, and various structural biology approaches used to study them. Since the genome of these viruses serves as a template for two mutually exclusive virological processes, namely genome translation and replication, the review also discusses how viruses can utilize RNA structure-based strategies to regulate the switch between genome translation and replication, highlighting future directions for exploring these fundamental virological processes to develop antiviral therapeutics able to combat diseases caused by these pathogens. Full article

The H7N9 influenza viruses, which are capable of causing severe respiratory syndrome in humans, were first discovered to infect humans in 2013 and continue to pose a persistent public health threat. Quail has been proposed as a potential intermediate host that may facilitate the emergence of novel reassorted influenza A viruses with the capacity to infect humans across species barriers; however, information on the biological characterization of quail H7N9 remains limited. In this study, we isolated and identified an avian H7N9 influenza virus from quails, designated as A/quail/Hebei/CH06-07/2018 (H7N9) and abbreviated as CH06-07, in Hebei, China. Phylogenetic analyses revealed that both the HA gene and the NA gene of CH06-07 were clustered in the Eurasian lineage. Furthermore, CH06-07 exhibited binding affinity for both α2,3-linked and α2,6-linked sialic acid receptors and demonstrated high pathogenicity in both quails and mice. Notably, transmission studies revealed that CH06-07 not only exhibited efficient inter-quail transmission and inter-guinea pig transmission but also demonstrated effective cross-species transmission. Importantly, infected quails and guinea pigs generated significant quantities of viral aerosols (≥18,998 ± 1672 copies per liter of air at 3 days post-infection), and infectious viruses were successfully recovered from environmental aerosols. These findings highlight the necessity for continuous surveillance of the prevalence of quail-origin H7N9 influenza A viruses in poultry populations due to their potential threat to human health. Full article

Influenza viruses, featured by high variability, pose a persistent public health threat because of an annual seasonal epidemic in the world and irregular global pandemic, requiring animal models to elucidate their pathogenic mechanisms and advance preventive strategies. Mice have been selected as the primary animal model, although several experimental animals have been used in studies of the influenza virus. However, the limited susceptibility of wild-type influenza viruses to mice poses significant challenges for studying pathogenesis and intervention strategies. Here, to help understand the construction of mouse-adapted influenza viruses, we reviewed the recent research progress in constructing mouse-adapted influenza virus strains to overcome species-specific barriers. Full article

Background/Objectives: Respiratory syncytial virus (RSV) is one of the main pathogens causing infections of the respiratory system. In our study, we investigated whether breastfeeding, compared to feeding with formula milk, has an effect on RSV infection in newborns and infants. Methods: We analyzed 51 patients hospitalized at Department of Pediatrics, Newborn Pathology and Bone Metabolic Diseases, University of Lodz, with RSV infection. The infants were divided into two groups by the type of the feeding mode: breast milk or formula milk. Results: Breastfed infants were hospitalized for less time compared to those fed with milk formula (8 days vs. 11 days, p < 0.05). A multivariate linear regression model showed that babies fed with formula milk spent an average of 1.7 days longer in hospital than those fed with breast milk (95% Cl 0.247–3.209). Conclusions: Breastfeeding could reduce the risk, and in some cases, also the severity of RSV infection. Full article

Oat (Avena sativa L.) is a vital cereal and feed crop grown worldwide, but its production is increasingly threatened by barley yellow dwarf virus (BYDV) and aphid infestations in arid and semi-arid regions, particularly in northern China. This study explores the transcriptomic and physiological responses of two oat cultivars MN10253 (resistant) and Qingyin 1 (susceptible) to BYDV at 0, 2, 8, 24, and 48 h post-infection. A combination of phytohormone profiling, differential gene expression analysis, and pathway enrichment was employed to identify mechanisms underpinning disease resistance. Comparative time-course transcriptome analysis revealed 9285 and 8904 differentially expressed genes (DEGs) in MN10253 and Qingyin 1, respectively. Key pathways such as MAPK signaling, plant–pathogen interaction, and hormone signal transduction were significantly enriched. The resistant cultivar exhibited robust activation of pattern-triggered immunity and effector-triggered immunity pathways, marked by upregulation of genes like RPS2, HSP90, and WRKY33, alongside higher expression of salicylic acid (SA)-responsive genes, such as NPR1 and PAL. Conversely, the susceptible cultivar displayed weaker or delayed activation of these defense pathways. Hormonal analysis further demonstrated higher SA accumulation in MN10253 during early infection, correlating with enhanced defense responses. In contrast, Qingyin 1 showed elevated levels of auxin and abscisic acid, which are linked to suppressed immunity. This study underscores the central role of immunity responses and phytohormone pathways in mediating oat resistance to BYDV, highlighting the tradeoff between growth and defense modulated by hormonal crosstalk. These findings advance our understanding of host–pathogen dynamics in oats and provide valuable insights for breeding disease-resistant cultivars. Full article

Background/Objectives: Classical swine fever (CSF) is listed by the World Organisation for Animal Health as a highly devastating and contagious pig disease, causing severe economic losses to the swine industry. In spite of the successful elimination of CSF in Taiwan, preparedness against potential reintroduction remains essential. The live attenuated vaccines have been effective in disease control, but are not capable of a viable strategy that differentiates infected from vaccinated animals (DIVA). Subunit vaccines are recognized for their safety and ability to induce protective immunity against infectious diseases. Methods: In this study, the recombinant CSF virus (CSFV) E2 proteins were formulated with a CpG motif as an adjuvant to produce the E2-CpG subunit vaccine. Its efficiency in specific-pathogen-free (SPF) pigs was compared with a commercially available E2 subunit vaccine (Bayovac^® CSF-E2; Bayer Taiwan Co., Ltd., Taipei City, Taiwan). Results: Significantly higher titers of anti-E2 antibodies were induced in pigs immunized with a single dose of the E2-CpG vaccine, particularly the reduced E-0.5A formulation, than those immunized with a dose of the commercialized E2 subunit vaccine adjusted to double dosage. This designed subunit vaccine showed high efficacy in protection against clinical symptoms and significant pathological alterations in pigs after a highly virulent CSFV (genotype 1.1) challenge. Viral shedding was not detected in vaccinated pigs before completion of the challenge study, and the viral load in their spleens remained undetectable. Conclusions: These results could support the potential of the E2-CpG vaccine as a cost-effective, single-dose subunit vaccine capable of inducing robust CSFV-specific immunity and providing 100% protection against lethal CSFV challenges. Full article