Search Results (406)

The expanding distribution and geographic range of mosquitoes have potentially contributed to increased flaviviral dissemination and transmission. Despite the growing burden of flaviviral infections, there are no effective antiviral treatments or vaccines, highlighting the need for novel therapeutic targets. Tetraspanins, a superfamily of transmembrane domain glycoproteins involved in cellular organization, signaling, and protein–protein interactions have been recognized as potential mediators of flaviviral infection and transmission. While their roles in vertebrate hosts have been explored, their involvement in flaviviral replication and dissemination within medically important vectors remains poorly understood. In this study, we investigated the role of arthropod tetraspanins in mosquito cells and extracellular vesicles (EVs) derived from cells infected with Zika virus (ZIKV) and dengue virus (serotype 2; DENV2). Among several of the tetraspanins analyzed, only CD151 was significantly upregulated in both mosquito cells and in EVs derived from ZIKV/DENV2-infected cells. RNAi-mediated silencing of CD151 led to a marked reduction in viral burden, suggesting its crucial role in flavivirus replication. Inhibition of EV biogenesis using GW4869 further demonstrated that EV-mediated viral transmission contributes to flavivirus propagation. Additionally, co-immunoprecipitation and immunofluorescence analyses revealed direct interactions between CD151 and ZIKV NS2B and DENV2 capsid proteins. Overall, our findings highlight the functional importance of mosquito CD151 in the replication and transmission of ZIKV and DENV2. This study provides new insights into the molecular mechanisms of flaviviral infection in mosquitoes and suggests that targeting vector tetraspanins may offer a potential approach to controlling mosquito-borne flaviviruses. Full article

Background/Objectives: In the last few decades, the dengue virus, a prevalent flavivirus, has demonstrated various epidemiological, economic, and health impacts around the world. Dengue virus serotype 2 (DENV2) plays a vital role in dengue-associated mortality. The RNA-dependent RNA polymerase (RdRp) of DENV2 is a charming druggable target owing to its crucial function in viral reproduction. In recent years, streptomycetes natural products (NPs) have attracted considerable attention as a potential source of antiviral drugs. Methods: Seeking prospective inhibitors that inhibit the DENV2 RdRp allosteric site, in silico mining of the Streptome database was executed. AutoDock4.2.6 software performance in predicting docking poses of the inspected inhibitors was initially conducted according to existing experimental data. Upon the assessed docking parameters, the Streptome database was virtually screened against DENV2 RdRp allosteric site. The streptomycetes NPs with docking scores less than the positive control (68T; calc. −35.6 kJ.mol⁻¹) were advanced for molecular dynamics simulations (MDS), and their binding affinities were computed by employing the MM/GBSA approach. Results: SDB9818 and SDB4806 unveiled superior inhibitor activities against DENV2 RdRp upon MM/GBSA//300 ns MDS than 68T with ΔG_binding values of −246.4, −242.3, and −150.6 kJ.mol⁻¹, respectively. A great consistency was found in both the energetic and structural analyses of the identified inhibitors within the DENV2 RdRp allosteric site. Furthermore, the physicochemical characteristics of the identified inhibitors demonstrated good oral bioavailability. Eventually, quantum mechanical computations were carried out to evaluate the chemical reactivity of the identified inhibitors. Conclusions: As determined by in silico computations, the identified streptomycetes NPs may act as DENV2 RdRp allosteric inhibitors and mandate further experimental assays. Full article

A Streptococcus suis strain isolated from the blood of a patient in Zhejiang Province, China, was analysed using whole-genome sequencing and tested for antimicrobial resistance. The isolated strain was identified as S. suis serotype 2, and classified to ST25 on multilocus sequence typing (MLST). The minimum core genome group of the strain was identified as Group 4, and multilocus variable-number tandem-repeat analysis (MLVA) assigned it as type 2, 4.4, 0, 9, 3, 2, 0, 0. An antimicrobial resistance analysis showed that the strain was resistant to clindamycin, tetracycline, azithromycin, and erythromycin but sensitive to 11 other antibiotics. In a genomic evolution analysis, this isolate clustered on the same branch as North American pig isolate, Chinese pig isolates from Tianjin, and Hubei pig isolates. Full article

Enteroviruses of the Picornaviridae family are transmitted primarily by the fecal–oral route. Transmission may occur following hand contact with contaminated fomites and subsequent ingestion of virus conveyed to the mouth by the contaminated hand. The persistence of these viruses on fomites likely plays a role in this transmission scenario. Six echoviruses (1, 2, 3, 5, 6, and 7) that cause frequently reported clinical cases in the United States were studied, along with poliovirus type 1 vaccine strain LSc-2ab. The infectivity half-lives of the enteroviruses deposited on vinyl tile coupons in a 10% fecal solution ranged from 1.7 to 12.6 h. The echovirus serotypes most commonly associated with reported infections persisted longer on the vinyl tiles than the less commonly reported types. This increased persistence on surfaces may favor the transmission of these echoviruses through the fecal–oral route. These results inform the future selection of appropriate model enteroviruses for challenging newly formulated and eco-friendly disinfectants or other strategies in infection prevention and control for enteroviruses. Full article

(1) Background: Understanding the distribution of Salmonella serovars in food, animals, and their environments is crucial for identifying infection sources and monitoring pathogen prevalence in the food chain. This study analysed Salmonella serovars in Poland from 2016 to 2020, focusing on their epidemiological significance. (2) Methods: Isolation of Salmonella was carried out following PN-EN ISO 6579 standards, and serotyping was performed using the White–Kauffmann–Le Minor scheme. A total of 7104 isolates were collected from food-producing animals, their environments, food of animal origin, feedingstuffs, and fertilisers. (3) Results: A total of 175 serovars were identified, with S. Enteritidis (n = 2905; 40.9%), S. Infantis (n = 1167; 16.4%), and S. Typhimurium (n = 360; 5.1%) being the most prevalent. Species-specific patterns were observed: S. Enteritidis dominated in chickens, ducks, and cattle; S. Kentucky in turkeys; S. Typhimurium in geese; and monophasic S. Typhimurium in pigs. S. Enteritidis and S. Infantis were most frequent in food of animal origin, especially broiler meat. In feedingstuffs, S. Agona was predominant, while fertilisers mostly contained S. Derby and S. Infantis. (4) Conclusions: The study highlights the source-dependent variety of Salmonella serovars and the importance of serotyping in tracing infection routes and preventing the spread of pathogens. Identifying the most common serovars supports the development of targeted preventive measures, including improved biosecurity, hygiene, and management practices to enhance food safety. Full article

Heart failure (HF) has become an epidemic, with a prevalence of ~7 million cases in the USA. Despite accounting for nearly 50% of all HF cases, heart failure with a preserved ejection fraction (HFpEF) remains challenging to treat. Common pathophysiological mechanisms in HFpEF include oxidative stress, microvascular dysfunction, and chronic unresolved inflammation. Our lab focuses on oxidative stress-mediated cellular dysfunction, particularly the toxic effects of lipid peroxidation products like 4-hydroxy-2-nonenal (4HNE). Aldehyde dehydrogenase 2 (ALDH2), a mitochondrial enzyme, plays a vital role in detoxifying 4HNE and thereby protecting the heart against pathological stress. ALDH2 activity is reduced in various metabolic stress-mediated cardiac pathologies. The dysfunction of coronary vascular endothelial cells (CVECs) is critical in initiating HFpEF development. Thus, we hypothesized that ectopic overexpression of ALDH2 in CVECs could mitigate metabolic stress-induced HFpEF pathogenesis. In this study, we tested the efficacy of intracardiac injections of the ALDH2 gene into CVECs in db/db mice—a model of obesity-induced type 2 diabetes mellitus (T2DM)—and their controls, db/m mice, by injection with ALDH2 constructs (AAV9-VE-cadherin-hALDH2-HA tag-P2A) or control constructs (AAV9-VE-cadherin-HA tag-P2A-eGFP). We found that intracardiac ALDH2 gene transfer increased ALDH2 levels specifically in CVECs compared to other myocardial cells. Additionally, we observed increased ALDH2 levels and activity, along with decreased 4HNE adducts, in the hearts of mice receiving ALDH2 gene transfer compared to control GFP transfer. Furthermore, ALDH2 gene transfer to CVECs improved diastolic function compared to GFP control alone. In conclusion, ectopic ALDH2 expression in CVECs can contribute, at least partially, to the amelioration of HFpEF. Full article

Adeno-associated virus (AAV) vectors face a critical translational challenge in ocular gene therapy due to pre-existing neutralizing antibodies (NAbs) whose seroprevalence limits patient eligibility. Standard NAb detection using non-ocular cell models (Human Embryonic Kidney 293T) may inadequately predict retinal transduction inhibition due to cell type-related variations in receptor usage and immunogenicity. This study established parallel NAb detection platforms utilizing human retinal pigment epithelial (ARPE-19) cells and standard 293T cells to systematically evaluate clinical serum samples against ophthalmologically relevant AAV serotypes (2, 5, 8, 9) via luciferase reporter-based transduction inhibition assays. Comparative analysis demonstrated ARPE-19 exhibited 42–48% higher NAb titers against AAV5/9 compared to 293T cells, with distinct serotype-biased neutralization hierarchies observed between cellular models. Furthermore, female-derived sera exhibited significantly elevated NAbs against particular serotypes in the ARPE-19 system. Critically, inter-serotype cross-neutralization correlation patterns differed substantially between cellular platforms. These findings demonstrate that physiologically relevant retinal cellular models provide essential immunological profiling data, revealing NAb characteristics obscured in standard assays. Consequently, employing retinal cell-based platforms is crucial for optimizing AAV serotype selection, patient stratification, and predicting clinical outcomes in ocular gene therapy. Full article

Dengue virus serotypes 1-4 (DENV1-4) have spread through tropical and subtropical countries, causing endemic and epidemic diseases. Recently, a novel field approach using the Wolbachia symbiont was proposed to suppress DENV transmission via the mosquito vectors Aedes aegypti and Aedes albopictus. Previously, we showed that a Wolbachia strain, wMelPop, suppresses DENV2 replication in the C6/36 albopictus cell line, with the mutant DENV2 appearing and replacing the wild type DENV2. In this study, we expanded the analysis to include replications of all DENV serotypes 1-4, effects of wAu Wolbachia in C6/36 cells, and wMelPop-influences on the Aag2 aegypti cell line. It was revealed that both wAu and wMelPop reduce all DENV infectious titers without dominant appearances of the mutant viruses, despite varied effects on the viral copy numbers. The host transcriptomic profiles by RNA-seq were also variously altered by wAu and wMelPop (ranging from 10 to 30%, Log₂FC > 2 or <−2, p < 0.05). Those transcripts were not further altered by DENV infection. In contrast, abundant transcriptomic alterations by DENV infection in naïve C6/36 and Aag2 cells were blocked by either wAu or wMelPop. These results indicate that Wolbachia prevents host cellular transcriptomic alterations which are induced by DENV infection, affecting the cellular homeostasis necessary for DENV replication. Full article

Dengue has been a serious public health concern in Nepal since the past few years, with concurrent big outbreaks occurring in 2022–2024. This cross-sectional study was conducted among febrile patients visiting hospitals in Mahottari district in southern Nepal. A total of 2141 dengue-suspected patients were investigated by routine laboratory assays and serological and molecular techniques, including real-time quantitative polymerase chain reaction (RT-qPCR). Among them, 455 (21.3%) were confirmed as dengue cases. The majority of dengue cases (435, 95.6%) had a primary dengue infection. The total bilirubin level was significantly higher in secondary dengue infection than in primary (p = 0.032). The major dengue virus (DENV) serotypes responsible for this outbreak were DENV-1 (45.5%) and DENV-2 (40.9%), while 13.6% patients had DENV-3 infection. DENV-3 infection showed a significantly higher viral load (median: 7.71 Log₁₀ copies/mL; range: 6.48–7.94) compared to DENV-1 (6.72 Log₁₀ copies/mL; 5.49–7.17) and DENV-2 (4.76 Log₁₀ copies/mL; 2.32–6.96). Adult patients exhibited a significantly higher viral load than children (p = 0.035). NS1- and IgM-positive as well as admitted patients had a higher viral load (p < 0.05). Co-circulation of multiple serotypes (DENV-1, -2, -3) was confirmed with the first introduction of DENV-1 and DENV-3 in Mahottari and surrounding areas in the 2023 outbreak. Identification of the circulating DENV serotypes is crucial to understanding the epidemiological trend and dynamics of population immunity. These findings underscore the need of nation-wide integrated surveillance, including genomic data generation, in Nepal for disease control, prevention, and potential vaccine implication. Full article

Food contamination by Salmonella poses a significant public health risk, rendering products unfit for consumption. This study aimed to evaluate the efficiency of ozone gas (O₃), applied in flow and at low pressures, in inactivating Salmonella on black peppercorns (Piper nigrum L.). Samples were inoculated with a cocktail of four Salmonella serotypes and subjected to ozonation under flow or low-pressure conditions in a hypobaric chamber. For the flow treatment, ozone gas at 16 mg L⁻¹ was humidified by passing it through a 40% (w/v) sodium chloride solution and applied for 2, 4, and 8 h. For the hypobaric chamber treatment, an inlet O₃ concentration of 60 mg L⁻¹ was used, with 10, 15, and 20 injections. The results showed that, under flow ozonation for 8 h, Salmonella was absent in 25 g of the sample. Ozone treatment increased pH, total titratable acidity (TTA), antioxidant activity (DPPH*), lightness (L*), color saturation (C*), total phenolic content (TPC), and the concentration of major essential oil compounds in all treatments. Under low-pressure ozonation, Salmonella persisted in all tested conditions, along with changes in color difference (∆E*), moisture content, TTA, DPPH*, L*, C*, pH, TPC, and the concentration of major essential oil compounds. The essential oil yield was not affected. Although the application of ozone at low pressures reduced Salmonella contamination, it was not sufficient for complete inactivation under the tested conditions. However, the flow-applied ozone treatment proved effective in the inactivation of Salmonella in black peppercorns. Full article

Dengue virus (DENV) infection is strongly associated with dengue hemorrhagic fever and dengue shock syndrome, both of which carry mortality risks. Addressing the urgent need for effective dengue therapeutics, we identified sofalcone, a gastroprotective agent with antioxidant and anti-inflammatory properties, as a potential inhibitor of DENV replication. Sofalcone demonstrated efficacy against all four DENV serotypes, with the dose inhibiting 50% (IC50) value of 28.1 ± 0.42 μM against viral replication of DENV serotype 2, without significant cytotoxicity. Additionally, sofalcone significantly improved survival rates and reduced viral titers in DENV-infected ICR-suckling mice. Mechanistically, sofalcone induced heme oxygenase-1 (HO-1) expression via the nuclear factor-erythroid 2-reated factor 2 (Nrf2) pathway, which in turn suppressed viral protease activity and restored antiviral interferon (IFN) responses. This included dose-dependent stimulation of IFN downstream antiviral genes such as 2′-5′-oligoadenylate synthetase 1 (OAS1), OAS2, and OAS3. Given its established clinical use as an anti-gastric ulcer drug, sofalcone offers promising potential for rapid application in treating DENV infection. Full article

Ecuador, a tropical country with frequent dengue outbreaks, including a surge from 16,017 cases in 2022 to 61,329 in 2024, was the focus of this study. The study was conducted in Borbon, a semi-urban rural town in the Esmeraldas province. Genomic analysis, alongside entomo-virological surveillance, provides valuable insights into DENV-2 genotypes. Five pools of female Aedes aegypti mosquitoes from Borbon tested positive for DENV serotype 2 through RT-qPCR. One positive pool (CT = 16.13) was sequenced using Illumina MiSeq, and genotyping was conducted via the Dengue Typing Tool and Maximum Likelihood phylogenetic tree. The genotype assigned was III Southern Asian-American. Comparison with other genomes revealed genetic similarity to a human dengue genome sequenced in 2021, also from Esmeraldas, clustering with genomes reported across the Americas, particularly from Colombia and Venezuela. This study enhances our understanding of dengue virus epidemiology in rural areas, emphasizing the critical role of clinical case surveillance and vector monitoring in guiding evidence-based interventions. Full article

Early determination of the Shiga toxin type of Shiga toxin-producing Escherichia coli (STEC) is crucial for guiding STEC-infected patients for proper and timely treatment and patient care. Most diagnostic microbiology laboratories rely on PCR assays to detect the presence of stx1 and/or stx2 and enzymatic immunoassays (EIA) to detect the presence of the Shiga toxins 1 and/or 2 in STEC-positive stool samples. Occasionally, the stool samples test positive for STEC by PCR assays but test negative for the presence of Shiga toxins. Insufficient toxin production under laboratory conditions is the main culprit of this discordance. To test whether EIA-based STEC detection could be improved, various clinical STEC strains were treated with mitomycin C, which is a commonly used inducer of Shiga toxin production. A dose-dependent increase in Shiga toxin production, in response to mitomycin C doses of up to 500 ng/mL, was observed without any bactericidal effects. Depending on the serotype, 5–50 times more Shiga toxin 2 was produced than Shiga toxin 1. Shiga toxin production was not induced by the mitomycin C treatment in certain STEC serotypes carrying the toxin subtypes stx1a, stx2a, 2b, 2f, or 2h. This diversity in toxin production indicates that other factors may determine toxin expression in certain STEC strains, which warrant further exploration. Full article

Streptococcus suis is a significant zoonotic pathogen of public health importance. In this study, whole-genome sequencing of 177 isolates of Streptococcus suis, isolated from diseased swine across 15 provinces in China between 2017 and 2019, was performed. A total of 23 serotypes and 28 ST types were identified, with serotypes 2 and 3 comprising 50.8% of the isolates, and sequence types ST353 and ST117 accounting for 23.7%. Clustering analysis based on known virulence-associated factors (VAFs) resulted in the identification of four distinct clusters, and virulence was assessed using animal models, including a unique, highly virulent cluster designated as cluster I. Drug susceptibility testing indicated that 97.7% of the isolates were multidrug-resistant. A total of 26 resistance-associated genes were identified within the genome, 18 of which were associated with integrative and conjugative elements (ICEs) and/or integrative mobilizable elements (IMEs). Nevertheless, our understanding of suis virulence in terms of phylogeny remains incomplete. This study contributes to the understanding of the population structure and genetic characteristics of suis, provides a framework and novel partitioning approach for future investigations into its virulence and pathogenicity, and complements the data on antibiotic resistance. Full article

Foot and mouth disease virus (FMDV) is a highly pathogenic virus that mainly infects cloven hooved animals, such as pigs. The establishment of a rapid, sensitive and accurate point-of-care detection method is critical for the timely identification and elimination of infected pigs for controlling this disease. In this study, a RT-RAA-CRISPR/Cas13a method was developed for the detection of FMDV serotype O in pigs. Six pairs of RT-RAA primers were designed based on the conserved gene sequence of FMDV serotype O, and the optimal amplification primers and reaction temperatures were screened. The CRISPR-derived RNA (crRNA) was further designed based on the optimal target band sequence and the most efficient crRNA was screened. The results revealed that FMDV-O-F4/R4 was the optimal primer set, and the optimal temperature for the RT-RAA reaction was 37 °C. Moreover, crRNA4 exhibited the strongest detection signal among the six crRNAs. The established RT-RAA-CRISPR/Cas13a method demonstrated high specificity and no cross-reactivity with other common swine pathogens such as Senecavirus A (SVA), porcine reproductive and respiratory virus (PRRSV), porcine epidemic diarrhea virus (PEDV), porcine circovirus type 2 (PCV2), classical swine fever virus (CSFV), and pseudorabies virus (PRV), additionally, it was observed to be highly sensitive, with a detection limit of 19.1 copies/µL. The repeatability of this method was also observed to be good. This method could produce stable fluorescence and exhibited good repeatability when three independent experiments yielded the same results. A validation test using three types of simulated clinical samples (including swab, tissue, and serum samples) revealed a 100% concordance rate. The detection results could be visualized via a fluorescence reader or lateral flow strips (LFSs). Thus, a highly specific and sensitive RT-RAA-CRISPR/Cas13a detection method was developed and is expected to be applied for the rapid detection of FMDV serotype O in situ. Full article