Search Results (28,732)

Bluetongue (BT) is an infectious, non-contagious, arthropod-borne viral disease of ruminants, and has a severe impact on livestock. It is caused by Bluetongue virus (BTV), a double-stranded (ds) RNA virus with a segmented genome (10 segments), belonging to the Seoreoviridae family, Orbivirus genus. Over the last 25 years, Europe has suffered multiple incursions of different BTV serotypes with serious consequences, which have mainly been controlled thanks to vaccination. In the case of Spain, from 2000 to 2023, BTV serotypes 1, 2, 4 and 8 have caused epidemics, and, sporadically, BTV-1 and -4 were detected in the same area and period. In 2024, BTV serotypes 1, 3 and 8 circulated simultaneously in the southwest of the country, causing a severe clinical impact in sheep but also in cattle and a multitude of outbreaks. Additionally, despite vaccination, serotype 4 also circulated that year, especially in areas where the other serotypes were already circulating. Whole-genome sequencing and phylogenetic analyses allowed us to confirm that serotypes 1 and 4 were homologous to viruses circulating in the country since 2000s, while serotypes 3 and 8 were homologous to BTVs recently notified in neighboring countries. In this context, many BTV co-infections of two or more different serotypes were confirmed by serotype-specific RT-PCRs, both in farms and individual animals. An epidemic caused by four serotypes coinciding in space and time had never occurred before in Spain, being a challenge for the diagnosis and control of this disease. Moreover, it could have favored the appearance of reassortant viruses with an unknown virulence, posing an additional risk. The data presented here raise the question of whether the co-circulation of different BTV strains, an exceptional situation, could become the new normal in certain areas of Europe. Full article

Background: Hepatitis C viral infection (HCV) has historically been a leading indication for liver transplantation (LTx), primarily due to its progression to cirrhosis and hepatocellular carcinoma (HCC). However, the advent of direct-acting antiviral agents (DAAs) over a decade ago has revolutionized HCV treatment, achieving sustained virologic response (SVR) in over 90% of patients and potentially altering LTx indications. Aim: To investigate the impact of DAAs on HCV-related indications, with or without HCC, and model future trends in LTx indications. Methods: We retrospectively reviewed 1504 liver transplants performed between 2000 and 2024 at a single center. Patients were categorized into three cohorts: HCV-only, HCC-only, and HCC with HCV co-infection (HCC/HCV). Relative transplant volumes by-year, post-operative outcomes, and HCC recurrence rates were analyzed across pre- and post-DAA eras. ARIMA modeling was employed to project trends in transplant indications through the year 2030. Results: The proportion of transplants for HCV alone declined by 82.3% from 2015 to 2020, while HCC/HCV transplants decreased by 68.8%. Conversely, the total number of transplants for HCC alone increased during this period, with a modest proportional decrease of 8.3% from 2015 to 2020. ARIMA modeling suggests that by 2030, LTxs for HCV alone may be nearly eliminated. The projected proportion of transplants conducted for HCC alone remains the highest of all three study indications at 4.3%. Conclusions: DAAs have reduced LTx due to HCV. By 2030, LTx for HCV-related cirrhosis, particularly without HCC, may be obviated. This underscores the need to reevaluate allocation for emerging oncologic indications. Full article

Wastewater surveillance emerged as a critical public health tool during the COVID-19 pandemic, enabling early detection of community-level pathogen circulation independent of clinical testing. Its ability to capture signals from both symptomatic and asymptomatic individuals highlighted the importance of optimizing sampling methodologies to improve sensitivity and reliability. A key question is whether the several-fold increase in SARS-CoV-2 detectability observed when using passive tampon swab sampling compared with paired grab samples also applies to other respiratory viruses, including influenza A (including its avian influenza H5N1 subtype), influenza B, and respiratory syncytial virus (RSV). We collected 24 h passive swab samples with same-day grab samples from Detroit sewersheds, concentrated and purified nucleic acids, and using RT-ddPCR, quantified respiratory syncytial virus, SARS-CoV-2, influenza A, influenza B, and H5N1 influenza A viruses using markers RSV, SC2, InfA, InfB, and H5, respectively. Samples testing positive for H5 (marker for H5N1 influenza A) were further analyzed by targeted PCR and amplicon sequencing. Across three sites, median 24 h swab:grab ratios of virus copies were 7.0 for RSV, 9.2 for SC2, 9.9 for InfA, and 3.6 for InfB. A 239 bp hemagglutinin sequence from a sample with a strong H5 signal (795 copies/10 mL) had 100% identity to avian influenza viruses from Canada geese. Twenty-four-hour swab sampling greatly improves viral detectability across diverse targets and enabled the first confirmed detection of H5 in Detroit wastewater. Combined with magnetic bead purification, the overall sensitivity gain over conventional PEG-NaCl-Qiagen methods is approximately 36-fold, enabling earlier warning of community pathogens than grab samples. By integrating 24 hour passive swab sampling with high-efficiency nucleic acid purification, we expand the sensitivity of wastewater surveillance to enable detection and confirmation of low-abundance pathogens like avian influenza (H5). Full article

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) represent fundamental cellular adaptive mechanisms that maintain protein homeostasis and metabolic balance. Many RNA viruses, particularly flaviviruses such as dengue virus (DENV), Zika virus (ZIKV), West Nile virus (WNV), yellow fever virus (YFV), and Japanese encephalitis virus (JEV), extensively remodel the ER to establish replication compartments and assemble progeny virions. This massive reorganization disrupts ER homeostasis, leading to UPR activation. Emerging evidence reveals that flaviviruses not only trigger but also manipulate the three UPR branches—PERK, IRE1, and ATF6—to optimize viral translation, replication, and egress. In parallel, flavivirus infection profoundly alters host lipid metabolism and promotes dynamic changes in lipid droplets (LDs), key organelles that mediate lipid storage and serve as scaffolds for viral replication and assembly. The UPR intimately connects to LD biogenesis through transcriptional and translational programs mediated by XBP1, ATF4, and ATF6, thereby coupling ER stress responses to lipid remodeling and energy homeostasis. This intricate crosstalk between UPR and LDs creates a metabolic and structural niche favorable for viral replication but detrimental to host cell integrity. This review provides a comprehensive analysis of the molecular mechanisms by which flaviviruses exploit ER stress and the UPR to reprogram lipid metabolism and LD dynamics. We highlight the dual role of UPR signaling in promoting adaptive lipid synthesis and initiating cell death under prolonged stress, discuss recent insights into ER–LD interactions during flavivirus infection, and explore therapeutic opportunities targeting UPR–lipid metabolic pathways as broad-spectrum antiviral strategies. Understanding this interconnected network will advance our knowledge of viral pathogenesis and identify new avenues for host-directed antiviral intervention. Full article

Viral internal ribosome entry sites (IRESs) are specialized RNA structures that facilitate cap-independent translation as a strategy to usurp the host translational machinery. The Type 6 IRESs are the most streamlined mechanism to date, as they adopt a three pseudoknot RNA structure to initiate factorless translation initiation by directly recruiting the ribosome and drive translation. The Halastavi árva virus (HalV) IRES represents the most minimalistic subclass identified to date, whereby the IRES lacks specific pseudoknot domains that bind to the 40S subunit but instead recruits pre-assembled 80S ribosomes via a mechanism that is not fully understood. Here, we examined cellular conditions that can support HalV IRES translation. We demonstrated that the HalV IRES is translationally active in insect Sf21 lysates and Drosophila S2 cells, but inactive in mammalian RRL and wheat germ extract. Cells treated with heat shock or serum starvation suppressed HalV IRES activity, whereas virus infection robustly enhanced HalV IRES-mediated translation. Finally, the HalV IRES can support viral translation and replication using a heterologous viral replicon. These findings highlight the context-specific cellular conditions that allow ribosome assembly and translation by a factorless minimalist IRES. Full article

Trichomonas vaginalis is the causative agent of trichomoniasis, the most common non-viral sexually transmitted infection worldwide. In these cases, 5-Nitroimidazoles, particularly metronidazole (MTZ), remain the primary treatment option; however, resistance to MTZ has been increasingly reported. This study aimed to evaluate the in vitro activity of D-form synthetic antimicrobial peptides and investigate transcriptional differences associated with MTZ resistance and peptide treatment in T. vaginalis. D-form synthetic peptides (D-TN1, D-TN3, and D-TN6) developed in the R&D Laboratory of Acibadem University were tested against metronidazole-susceptible (T. vaginalis ATCC 30236) and metronidazole-resistant (T. vaginalis ATCC 50143) strains by minimum lethal concentration (MLC) assays. D-TN1 exhibited an MLC of 16 µg/mL in both strains, whereas D-TN3 and D-TN6 exhibited MLC values of 32 µg/mL and 16–32 µg/mL, respectively. Comparative transcriptomic analysis was conducted to investigate transcriptional differences. Differential gene expression analysis identified 3395 genes between the resistant and susceptible isolates and 3060 genes in the D-TN1-treated resistant isolate (FDR < 0.05, |log₂FC| ≥ 1). D-TN1 treatment in the resistant isolate was associated with downregulation of ribosomal and metabolic pathways. If confirmed with further in vivo studies, this new antimicrobial peptide may become a new therapeutic alternative in the treatment of trichomoniasis in the future. Full article

Infectious bursal disease virus (IBDV) is an immunosuppressive pathogen posing a major threat to poultry health worldwide. Its marked phenotypic variability is driven by the rapid evolution of its double-stranded RNA genome, primarily achieved through mutation and reassortment. Although extensive evidence has been generated on molecular determinants of antigenicity and pathogenicity, interpretation is often hindered by heterogeneity and lack of systematicity. This scoping review synthesizes over 35 years of research on amino acid positions influencing IBDV phenotype. A total of 62 studies reporting 107 functionally relevant sites were identified and critically appraised based on evidence type, methodological approach, and ability to infer causality. The results confirmed the central role of VP2, particularly its hypervariable region, while also highlighting the increasingly recognized contribution of other viral proteins. Despite good agreement, comparability across studies was limited by substantial heterogeneity in experimental design and the frequent focus on partial genomic regions. Notably, some molecular markers were context-dependent or inconsistently associated with phenotypic outcomes, underscoring the need for proper interpretation of molecular determinants and for more standardized and comprehensive approaches, including full-genome analyses and reverse genetics. Overall, these findings provide a valuable framework for enhancing molecular diagnostics and supporting the rational design of next-generation vaccines. Full article

H5 subtype avian influenza virus (AIV) can infect both chickens and ducks, leading to substantial economic losses. Nevertheless, certain strains cause silent infections in ducks. In this study, a goose-origin clade 2.3.4.4h H5N6 AIV was isolated, which caused high mortality in mixed-gender white leghorn chickens but no deaths in mixed-gender mallard ducks. After independent serial in vitro passage in duck embryo fibroblasts (DEFs) and in vivo passage in specific-pathogen-free (SPF) ducks, the DEF-passage 10 (P10) virus induced markedly higher mortality rates and viral loads in SPF ducks compared to the DEF-P1 virus and the original parental virus prior to passage. Similarly, the in vivo-passaged P3 and P4 viruses exhibited significantly higher mortality rates than the P1 virus in SPF ducks, with 100% mortality and markedly increased viral titers in the organs. A whole-genome SNP analysis identified seven high-frequency mutations in the M1, NA and NS1 proteins. The NS1-F161L substitution virus exhibited significantly increased mortality rates, viral loads in multiple tissues, and a robustly induced innate immune response in ducks. Furthermore, dynamic evolutionary variations in the NS1 protein among global H5 avian influenza viruses revealed that the NS1-F161L substitution became dominant in clade 2.3.4.4b viruses in 2021 and subsequent years. Collectively, our findings demonstrate that host-driven adaptation can rapidly increase the pathogenicity of H5N6 AIVs in ducks and identify NS1-F161L as a critical virulence marker. These results offer novel insights relevant to the molecular surveillance, virulence prediction, and risk assessment of circulating H5 AIVs in waterfowl. Full article

The most common complication of active brucellosis in humans is osteoarticular injury. In the bone marrow microenvironment, mesenchymal stem cells (MSCs) can differentiate into either adipocytes or osteoblasts, and this balance is tightly regulated because an increase in adipogenesis may negatively affect bone formation and favor bone loss. The differentiation of MSCs into adipocytes or osteoblasts is tightly regulated by mechanisms that promote cell fate toward one lineage while repressing the other. Our study demonstrated that Brucella abortus infects MSCs but does not affect the deposition of organic and mineral matrix during osteoblast differentiation. However, the infection upregulates Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL) expression in osteoblasts, which may contribute to osteoclast activation and bone resorption. Conversely, B. abortus infection significantly influences adipocyte differentiation by modulating lipolysis, lipogenesis, and interactions between lipid droplets and mitochondria. This leads to increased cellular cholesterol levels and reduced intracellular triglycerides, accompanied by glycerol release. These changes result in more differentiated adipocytes and larger lipid droplets. Consequently, we observed increased IL-6 secretion and a higher leptin/adiponectin ratio. Importantly, these effects were independent of a functional type IV secretion system (T4SS), as purified Brucella DNA fully reproduced the adipogenic phenotype. Moreover, inhibition of TLR9—the primary sensor of bacterial DNA—significantly reduced the DNA-induced adipogenic response, demonstrating that adipocyte modulation is at least in part mediated through TLR9 signaling. In summary, B. abortus promotes MSC differentiation toward an inflammatory adipocyte phenotype. It involves a TLR-9-mediated DNA detection. It may contribute to osteoarticular injury and infection-associated bone resorption. Full article

Background/Objectives: Tunisia lacks recent national data on hepatitis B virus (HBV) prevalence, particularly following the introduction of universal HBV vaccination in 1995. A national HBV seroprevalence study is essential to guide prevention strategies. This study aimed to estimate the national seroprevalence of HBV infection and identify its determinants 20 years after vaccine introduction. Methods: We conducted a nationwide, household-based, cross-sectional sero-epidemiological survey among a representative sample of the Tunisian general population using a two-stage cluster sampling method. The study was conducted by the National Observatory of New and Emerging Diseases (ONMNE) between December 2014 and June 2015. Data were collected using standardized questionnaires, and blood samples were tested using electrochemiluminescence (ECLIA) to detect HBV biomarkers (HBsAg, anti-HBc, anti-HBs). HBV infection was defined as the presence of HBsAg and/or anti-HBc with the absence of anti-HBs. Associations between HBV infection and explanatory variables (socio-demographics, vaccination status, intrafamilial transmission, and hospital exposures) were assessed using multivariate logistic regression, reporting adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Results: Among 21,720 participants, 19,155 (88.2%) were tested. The national prevalence of HBsAg was 1.7% (95% CI: 1.55–1.85%), higher among males (2.1%; 95% CI: 1.9–2.4%) than females (1.4%; 95% CI: 1.3–1.6%) (p < 0.001; M/F ratio = 1.48). The mean age of HBsAg-positive participants was 48 ± 15.7 years. Prevalence was highest in the Central (2.3%; 95% CI: 2.0–2.7%) and Southern regions (2.2%; 95% CI: 1.8–2.8%) (p < 0.001). In multivariate analysis, independent risk factors for HBV infection included age >20 years (aOR = 15.10; 95% CI: 4.79–47.64; p < 0.001), having a family member with HBV infection (aOR = 2.82; 95% CI: 2.09–3.79; p < 0.001), residing in the Southern (aOR = 2.51; 95% CI: 1.76–2.71; p < 0.001) or Central region (aOR = 2.18; 95% CI: 1.76–2.71; p < 0.001), male gender (aOR = 1.69; 95% CI: 1.39–2.05; p < 0.001), and hospital follow-up (aOR = 1.23; 95% CI: 1.01–1.51; p = 0.039). HBV vaccination was strongly protective (aOR = 0.36; 95% CI: 0.20–0.62; p < 0.001). Conclusions: The national HBsAg seroprevalence in Tunisia was 1.7%, reflecting a low-endemic status. Vaccination programs should prioritize high-risk groups, including males, adults over 20 years, household contacts of HBV carriers, and residents of the Central and Southern regions. Strengthening infection prevention and control in healthcare settings and adopting intrafamilial precautions among high-risk populations are essential for long-term HBV control. Full article

Background: Chronic viral hepatitis is a major global health problem associated with progressive liver injury and an increased risk of cirrhosis and hepatocellular carcinoma. The identification of novel biomarkers may improve disease monitoring and diagnostic accuracy. Methods: In this prospective case–control study, a total of 90 participants were included: 20 patients with chronic hepatitis B (CHB); 20 with chronic hepatitis C (CHC); 20 with HBeAg-negative chronic infection (HCI); and 30 age-, sex-, and body mass index-matched healthy controls. Serum irisin and nesfatin-1 levels were measured using enzyme-linked immunosorbent assays (ELISAs). Group comparisons were performed using multivariate analysis of variance (MANOVA) followed by Scheffé post hoc tests. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance. Results: Significant differences were observed among groups in terms of irisin, nesfatin-1, total bilirubin, and platelet counts (p ≤ 0.05). Nesfatin-1 levels were significantly higher in all patient groups compared with healthy controls (p < 0.001). Irisin levels were only significantly lower in the HCI group (p < 0.001). ROC analysis indicated that nesfatin-1 may have the potential to discriminate between infected patients and healthy individuals; however, the generalizability of this finding is limited by the study design and sample size. Conclusions: Nesfatin-1 may represent a potential biomarker for chronic viral hepatitis, whereas alterations in irisin levels may be more specific to the inactive carrier phase. Full article

Background/Objectives: SARS-CoV-2 is the causative agent of COVID-19, an infectious viral respiratory disease with human-to-human transmission. Current molecular understanding of how hosts respond to infection by respiratory viral pathogens in general and to SARS-CoV-2 in particular is still a research field under development. The activation levels of various host pathways are dependent on several variables, including the host tissue compartment. Methods: In this work, Illumina RNA sequencing was performed to assess the transcriptional host response to SARS-CoV-2 infection using COVID-19 PCR testing nasopharyngeal (NP) swab remnants from twenty infected and nine non-infected individuals. Results: Differential gene expression (DGE) analysis identified 182 overexpressed genes, with strong enrichment in innate immune and viral response genes. This included a significant induction of IFIH1/MDA5, a pattern recognition receptor (PRR) gene participating in the initial sensing of viral RNAs and subsequent cascade activation of interferon (IFN) and IFN-stimulated genes (ISGs). Interestingly, we observed different levels of concordance with previous similar studies and a significant induction of RIG1 and TLR3, two PRR genes encoding proteins that function to upregulate IFN and ISGs, but which are not normally identified as differentially expressed genes (DEGs). Finally, the overexpression of MX1, a well-characterized biomarker of viral infection; IFIT1, one of the top upregulated genes; and OAS1, OAS2 and OAS3, genes with a molecular function, 2-5-oligoadenylate synthase activity, identified as enriched in the DGE analyses, was confirmed by RT-qPCR. Conclusions: This study provides insights into upper respiratory tract responses to SARS-CoV-2 infections and identifies a set of differentially expressed genes (DEGs) with potential as candidates for further investigations as viral infection biomarkers. Full article

Hyperbranched poly(β-amino ester) (HPAE) is identified as a unique non-viral carrier capable of sustaining high-efficiency transfection under elevated plasmid concentrations, overcoming the aggregation and toxicity limitations of conventional lipid and PEI reagents. We demonstrate that transfection enhancement is driven by concentration-dependent synergism between membrane accumulation and endosomal escape. Guided by this mechanism, a half-volume transfection strategy was established to transiently elevate plasmid concentration without compromising cell viability, enabling superior lentivirus yield and purity. These findings define plasmid concentration as a previously overlooked regulatory axis in nanoparticle-mediated gene delivery and position HPAE as a high-performance platform for scalable therapeutic vector production. Full article

Objective: Hepatitis B virus (HBV) is a globally distributed infectious disease affecting the liver. This literature review aims to summarize all available relevant information on the PubMed database about HBV’s connection to the microbiome and to consider possible treatment adjuncts. Materials and methods: Database used: PubMed. Keywords used: “HBV”, “Hepatitis B”, “microbiome”. In the PubMed database, 179 research publications were identified using these keywords; 69 studies were excluded as they were irrelevant or retracted. Of the remaining, 110 were analyzed in this literature review, and four additional literature sources were used to supply background information and context. Information was summarized. The analysed studies in total included 14,814 participants (excluding animal studies), of whom 8564 were HBV-infected individuals. Results: Results characterizing abundance or decrease in specific bacterial, viral, and fungal species are heterogeneous; multiple studies support that the HBV patient oral and fecal microbiome is different from that in healthy controls (HCs) and varies throughout disease progression. The HBV seems to transform the microbiome negatively, leading to dysbiosis and decreased microbial diversity in most studies. Evidence links HBV microbiome changes with influence on HbeAg seroconversion, HBV-DNA load, metabolic pathways, liver cirrhosis, and hepatocellular carcinoma. The research proposes that members of microbiota could potentially promote or protect against liver injury in HBV. Four studies proposed that the plasma virome in HBV patients was primarily composed of members of the Anelloviridae. One study researched a parasite (Entamoeba gingivalis) in HBV patients. Two studies analyzed HBV patients’ fungal profiles. Conclusions: Microbiota research, although promising, at the present moment is heterogeneous. HBV patients’ microbiota is distinguishable from HCs, and multiple studies have tried to identify the HBV characteristic microbiome; however, more precise information is needed to draw conclusions. Fecal microbiota transplantation and probiotics have the potential to be therapy adjuncts for HBV patients, but more research is needed. Full article

Background/Objectives: It is challenging to develop efficient vaccines against intracellular pathogens such as viruses, and since viral infections are one of the main challenges for farmed salmon, a novel vaccine strategy is needed. mRNA vaccines are optimized and approved for humans, but for fish, the mRNA technology is new, and optimization is required to ensure efficient protein expression. We made an mRNA tailored to salmon and studied the effect of modified nucleosides and the length of the poly(A) tail on protein expression from in vitro-transcribed mRNA in CHSE-214 cells, using enhanced green fluorescent protein (EGFP) as a reporter. Methods: Different lengths of the poly(A) tail were tested, and various modified nucleotides were incorporated in the mRNA during in vitro transcription, including pseudouridine (Ψ), N1-methylpseudouridine (m1Ψ), N6-methyladenosine (m6A), 5-methyluridine (m5U), and 5-methylcytidine (m5C). Protein expression was observed in fluorescence microscopy and quantified using flow cytometry. Results: mRNA containing Ψ resulted in the strongest EGFP expression 1–3 days post-transfection (dpt), while EGFP expression from m5C mRNA was high throughout the experiment (<10 dpt). m5U-containing mRNA had low EGFP expression until 6 dpt, but reached the level of m5C mRNA at 10 dpt. The m5U mRNA, however, expressed EGFP at much higher intensity than all the other mRNAs at all time points. Poly(A) tails with lengths of 40, 100, and >100 were tested, and the one with >100 adenines showed the highest expression. The effects of phosphatase treatment and purification of the mRNA were also investigated. Furthermore, EGFP expression was observed in yolk-sac salmon larvae following micro-injection. Conclusions: Our study provides an important basis for the development of efficient mRNA-based vaccines in the future. Full article