Search Results (487)

Feline calicivirus (FCV) is among the few members of the Caliciviridae family that can replicate efficiently in vitro. Our recent studies have found the Transferrin Receptor Protein (TFRC) is an entry receptor that facilitates the internalization of FCV. To explore the potential involvement of additional host factors in conjunction with TFRC during the viral entry process, we identified metabotropic glutamate receptor 2 (mGluR2) as a specific interacting partner for both TFRC and the FCV VP1 protein by Co-IP analysis. Our findings indicate that the downregulation of mGluR2, along with its downstream signaling molecule, Calcium-activated potassium channel subunit alpha-1 (KCa1.1), significantly inhibits FCV replication by impairing viral internalization. Importantly, the knockout of TFRC did not diminish the effects of mGluR2 and KCa1.1 on FCV infection. Furthermore, mGluR2 was found to interact directly with FCV VP1, rather than with TFRC, and the rate of F-actin polymerization induced by FCV infection was reduced solely by the downregulation of mGluR2 protein expression, not by TFRC knockout. These results suggest that mGluR2 may independently mediate FCV internalization, operating independently of TFRC, and plays a critical role in the formation of endocytic vesicles. Overall, the results indicate that multiple host factors, including TFRC and mGluR2, are involved in the internalization of FCV into host cells. Further research is necessary to explore the propagation of other caliciviruses, such as norovirus, in vitro. Full article

The objective of this study was to evaluate the antiviral activity of glucosyl hesperidin (GH), a water-soluble derivative of hesperidin with known antioxidant and anti-inflammatory properties, in order to explore its potential applications. Antiviral activity was assessed using feline calicivirus (FCV), a surrogate model for human norovirus, a major foodborne pathogen. Cytotoxicity testing in Crandell–Rees feline kidney (CRFK) cells demonstrated that GH exhibited high biocompatibility, maintaining 100% cell viability at concentrations up to 8000 μM. Antiviral efficacy assays revealed that GH inhibited FCV replication in a concentration-dependent manner across the range of 250~8000 μM, with a half-maximal inhibitory concentration (IC₅₀) of 3281 μM. Complete viral inhibition, however, was not achieved at the maximum concentration tested. In conclusion, GH was shown to inhibit FCV while maintaining low cytotoxicity, indicating its potential as a natural, water-soluble candidate for the suppression of norovirus. Full article

Norovirus (NoV) is a symptomatic virus that is the leading cause of gastrointestinal disease. It spreads easily through the fecal–oral route and contact with contaminated food or surfaces. Maintaining a high level of hygiene in food industry settings and refocusing food production on isolating and testing natural compounds that exhibit antimicrobial and antioxidant properties are important elements in preventing NoVs infection. This study evaluated plant extracts prepared by cold brew and cold concentrate techniques for their antioxidant and antiviral activity. The extracts obtained demonstrated high antioxidant activity, with notable variation depending on the plant material, ranging from moderate to very strong levels. Correspondingly, high antiviral potential was observed, reaching the nearly complete inactivation of the virus. Remarkably, the highest virucidal effects were already achieved at relatively elevated, but not maximal, antioxidant activity levels. The results of the study indicate that cold water extraction techniques allow for the obtention of plant extracts showing strong virus-inactivating activity and favorable antioxidant activity. Full article

Human norovirus (HuNoV), a primary cause of foodborne illness, is frequently transmitted through contaminated berries. Serbia is a global producer of raspberries and other berries, yet data on HuNoV prevalence and genogroup diversity are limited. This study aimed to assess the prevalence, viral load, and genotypes of HuNoV circulating in raspberries and blackberries marketed in Serbia. A total of 450 berry samples were collected in 2023 from orchards, cold storage facilities, local markets, and roadside vending stands. Norovirus RNA was extracted using a modified ISO 15216-2 protocol. RT-qPCR positive samples were subsequently quantified by digital RT-PCR (RT-dPCR). Genotyping employed next-generation sequencing (NGS) of genome encoding major and minor capsid proteins, supplemented by Sanger sequencing. Nineteen samples (4.2%) tested positive for HuNoV, including four GI and fifteen GII strains, with higher prevalence in frozen (11.1%) than fresh berries (2.0%). Viral loads ranged from 34–105 gc/g for GI and 23–658 gc/g for GII, with medians of 72 and 153 gc/g, respectively. Genotypes GI.6, GII.2, GII.4, and GII.7 were identified, each represented by more than two sublineages and multiple introduction events detected by phylogenetic analysis. RT-dPCR provided precise quantification, while NGS enabled genotype characterization, together supporting enhanced surveillance, risk assessment, and management of norovirus contamination in berries destined for domestic and international markets. Full article

Neonatal calf diarrhoea (NCD) is the leading cause of mortality in calves under 30 days old. Although several pathogens are usually involved in outbreaks, most previous research has focused on specific enteropathogens or on the four agents traditionally associated with this syndrome. This study aimed to determine the prevalence of thirteen enteropathogens in 420 diarrhoeic calves under a month of age from north-western Spain and to identify the most frequent co-occurrences. Four diarrhoeagenic pathotypes of Escherichia coli, bovine rotavirus A, coronavirus, norovirus, nebovirus and torovirus were identified using qPCR. Presence of Salmonella spp. was studied using a serum agglutination test. A direct immunofluorescence assay was employed to identify Cryptosporidium and Giardia duodenalis oo/cysts. Eimeria oocysts were found by the floatation technique. Our results confirm the co-occurrence of agents in most cases of NCD. A total of 172 pathogen combinations, involving up to seven agents, were identified. Cases involving one or more viral agents and Cryptosporidium parvum were predominant, maybe because viral immunosuppression facilitates the protozoan life-cycle. The frequent detection of agents typically overlooked in the aetiological diagnosis of NCD suggests that they may play a role in this syndrome and thus should be included in routine diagnostic panels, allowing implementing the most effective control measures. Full article

Microbial contamination in frozen beverages threatens public safety and food quality. By systematically analyzing safety incidents, potential microbial hazards can be identified. This study reviewed 155 microbial safety incidents related to frozen beverages reported by nine international regulatory agencies from January 2015 to December 2024, as well as 903 incidents published by the State Administration for Market Regulation of China. The results indicate a higher risk in Southeast Asia, particularly in Malaysia (16.13%) and Thailand (11.61%). In China, the risks are concentrated in South China (Guangdong, 14.52%), Northeast China (Liaoning, 10.20%; Heilongjiang, 9.87%), and the Huang-Huai-Hai region (Henan 6.87%; Shandong 5.99%). Statistical analysis reveals that non-compliance incidents related to coliforms account for 67.7% globally, while incidents involving pathogens such as Listeria monocytogenes, Staphylococcus aureus, Salmonella, and Norovirus account for 6.4%. The characteristics in the Chinese market align with global trends, with the highest proportion of coliform exceedance (41%), while the incidence of pathogenic contamination remains relatively low (0.6%). Further analysis of different types of frozen beverages (ice cream, ice milk, ice frost, ice lolly, sweet ice, edible ice, and others) and their association with microbial hazards reveals significant issues with ice cream products globally; however, in the Chinese market, the contamination problems with ice milk and ice lolly are more severe. This study provides regional and category-specific data for the microbial risk assessment of frozen beverages and offers guidance for regulatory agencies and enterprises to implement targeted control measures, including optimizing sampling plans, enhancing hygiene controls during production processes, and promoting compliance in cold chain management. Consequently, this approach effectively reduces the risk of foodborne diseases and enhances the overall safety level of the industry, demonstrating significant practical application value and public health significance. Full article

Pathogenic enteric viruses are a leading cause of gastroenteritis-related mortality worldwide. However, the architecture of this research field remains poorly quantified. This bibliometric analysis provides a comprehensive overview of 35 years of global scientific output on major enteric viruses, such as rotavirus, norovirus, astrovirus, sapovirus, and non-polio enteroviruses, to map trends, methodological developments, and geographic disparities. We conducted a systematic search of PubMed and Scopus (1990–2024), identifying 10,017 records. After deduplication and eligibility screening, a final corpus of 8320 publications was analyzed using Bibliometrix (Biblioshiny 5.0) in R (version 4.3.0) and VOSviewer (Version 1.6.20). We found that scientific production grew steadily (CAGR = 5.84%), reaching its peak in 2021. The field is characterized by profound thematic and geographic disparity: rotavirus dominated the literature (56.3% of publications), followed by norovirus (30.8%), while other viruses were severely underrepresented (<9% each). Geographically, output was highly concentrated, with the top five countries (the USA, China, Japan, India, and Brazil) producing 92.4% of the publications. In contrast, high-burden regions, such as sub-Saharan Africa and Latin America, contributed only 7.6%. Genomic sequencing gained prominence, being cited in over 26.2% of publications from 2020 to 2024, reflecting a methodological shift accelerated by the application of wastewater-based epidemiology during the COVID-19 pandemic. In conclusion, while genomic tools and environmental monitoring are transforming enteric virus research, its progress is hampered by deep and persistent inequalities. These include a narrow focus on rotavirus and a significant disparity between regions with high disease burdens and those with high research outputs. Closing this gap requires targeted investments in equitable collaboration, local genomic capacity, and integrated public health interventions combining vaccination, WASH, and One Health strategies. Full article

Human noroviruses (HuNov) are the major cause of foodborne illness globally. Several HuNoV outbreaks have been linked to contaminated ready-to-eat seaweed products. Standard protocols such as the ISO 15216 show limited efficiency in extracting foodborne viruses from seaweed products. Therefore, we evaluated the efficiency of an extraction protocol based on porcine gastric mucin conjugated magnetic beads (PGM-MBs) to recover HuNoVs from Wakame seaweed salad. Compared to other HuNoV extraction methods, the PGM-MB method was more efficient. We then aimed to further improve this protocol by modifying several factors such as the buffers, pH, bead concentration, centrifugation and incubation time. The optimized PGM-MB method yielded 19 ± 3% and 17 ± 4% recovery, for HuNoV GI and GII, respectively. The limit of detection (LOD₉₅) for Wakame seaweed salad was 131 and 56 genomic equivalents per 25 g for HuNoV GI and GII. Although some variability in recovery efficiency was observed between the PGM sources, the optimized PGM-MB protocol effectively extracts HuNoVs from Wakame seaweed salads of various brands and other commodities such as dates, green onions, and salted seaweed. These results support the implementation of the optimized PGM-MB method as a viable alternative for HuNoV surveillance in complex food matrices. Full article

Human noroviruses (HuNoVs) stand as the primary cause of acute viral gastroenteritis outbreaks worldwide, particularly impacting children under the age of five. In Russia, reports of norovirus gastroenteritis have surged, especially in the post-COVID-19 era starting in 2022, with elevated infection rates reported into 2024. These viruses exhibit significant mutational variability, leading to the emergence of recombinant strains that can evade immune responses. A comprehensive examination of the complete genome is crucial for understanding the evolution of norovirus genes and for predicting potential outbreaks. This research focuses on analyzing the genotypic composition of HuNoVs circulating in the Sverdlovsk region during 2024, using Sanger sequencing and next-generation sequencing (NGS). Biological samples were collected (n = 384) from patients diagnosed with norovirus infection within the region. Bioinformatics analysis targeted the nucleotide sequences of the ORF1/ORF2 fragment and the assembly of complete genomes for the GII.4 and GII.7 genotypes. In total, 220 HuNoVs were characterized, representing 57.3% of the collected samples. The main capsid variants forming the predominant genotypic profile included GII.4 (n = 88, 40%), GII.7 (n = 86, 39%), and GII.17 (n = 14, 6%). Using NGS, we successfully assembled 8 out of 10 complete genomes for noroviruses GII.4[P16] and GII.7[P7]. Non-synonymous substitutions appeared at amino acid sites corresponding to the subdomains of VP1 in these strains. This molecular–genetic analysis provides contemporary insights into the genotypic composition, circulation patterns, and evolutionary dynamics associated with the dominant genovariants GII.4[P16] and GII.7[P7]. Full article

Bovine Norovirus (BNoV) is a member of the enterovirus family that can cause gastroenteritis in calves. This virus poses a significant risk to calf growth and development as well as to the long-term sustainability of the cattle industry in China and elsewhere. No specific treatment or vaccine is currently available; thus, the development of a safe and effective vaccine is paramount. Here, we describe a strategy to assemble BNoV virus-like particles (VLPs) using the insect baculovirus expression system (BEV) to express the major structural protein, VP1, and demonstrate their potentiality as vaccines. The results showed that the BNoV-VLP self-assembled into complete spherical particles with a diameter of approximately 40 nm. When it was immunized in mice, the levels of specific IgG and IgA antibodies peaked at weeks 6 and 7 post-immunization, respectively, with maximum titers of 1:25,600 and 1:200. Moreover, we observed a significant increase in the CD4⁺/CD8⁺ T-cell ratio in splenic lymphocytes of immunized mice (p < 0.05), accompanied by a significant increase in TNF-α⁺CD4⁺ T-cells and TNF-α⁺CD8⁺ T-cells (p < 0.05). These results demonstrate that BNoV-VLPs are promising vaccine candidates for providing immunoprotection in the future. These studies support the significant practical implications of using a scientific basis for the development of a BNoV-VLP vaccine. Full article

Norovirus–bacterial interactions influence viral replication and immune responses, yet the molecular details that mediate binding of these viruses to commensal bacteria are unknown. Studies with other enteric viruses have revealed that LPS and other lipid/carbohydrate structures facilitate virus–bacterial interactions, and it has also been shown that human noroviruses (HuNoVs) can interact with histo-blood group antigen (HBGA)-like compounds on the surface of bacterial cells. Based on these findings, this study hypothesized that carbohydrate-based compounds were the ligands that facilitated binding of both human and murine noroviruses (MNV) to bacteria. Using glycan microarrays, competitive inhibition assays, and a panel of bacterial mutants, the project assessed the influence of specific glycans on viral attachment to bacteria. Protein-based interactions were also examined. The results supported previous work which demonstrated that HuNoVs strongly bind HBGA-like glycans, while MNV displayed distinct binding to other glycans including aminoglycosides and fucosylated structures. Ultimately, this work demonstrates that HuNoVs have more limited binding requirements for bacterial attachment compared to MNV, and the MNV binding to bacteria may involve both specific structures as well as electrostatic interactions. Given the importance of commensal bacteria during viral infection, defining the molecular mechanisms that mediate virus–bacteria interactions is critical for understanding infection dynamics and may be useful in the development of disease therapeutics and novel technologies for viral detection from food and environmental sources. Full article

Foodborne diseases represent a significant public health challenge worldwide. This study systematically analyzed the temporal dynamics, key predictors, and seasonal patterns of pathogen-specific foodborne diseases using a dataset of 56,970 cases from Zhejiang Province, China, spanning 2014 to 2023. A comprehensive set of 91 candidate variables was constructed by integrating epidemiological, environmental, socioeconomic, and agricultural data. Lasso regression was employed to identify 41 important predictors. Based on these variables, supervised machine learning models (Random Forest and XGBoost) were trained and evaluated, achieving training set classification accuracies of 86% and 87%, respectively, demonstrating robust performance. Feature importance analysis revealed that patient age, food type, climate policy, and processing methods were the most influential determinants, highlighting the combined impact of host, exposure, and environmental factors on disease risk. The results demonstrated significant shifts in the pathogen spectrum over the past decade, including a steady decline in Vibrio parahaemolyticus, an increase in Salmonella after 2016, and persistent seasonal peaks in Norovirus and Vibrio parahaemolyticus during warmer months. Seasonal ARIMA modeling and time-series decomposition further confirmed the critical role of seasonal and trend components in bacterial incidence. Overall, this study demonstrates the value of integrating machine learning and time-series analysis for pathogen-specific surveillance, risk prediction, and targeted public health interventions. Full article

Determining the transmission routes of pathogens in indoor environments is challenging, with most studies limited to specific case analyses and pilot experiments. When pathogens are instantaneously released by a patient in an indoor environment, the peak infection risk may not occur immediately but may instead appear at a specific moment during the pathogen’s spread. We developed a concise model to describe the temporal crest of infection risk. The model incorporates the transmission and degradation characteristics of aerosols and surface particles to predict infection risks via air and surface routes. Only four real-world outbreaks met the criteria for validating this phenomenon. Based on the available data, norovirus is likely to transmit primarily via surface touch (i.e., the fomite route). In contrast, crests of infection risk were not observed in outbreaks of respiratory diseases (e.g., SARS-CoV-2), suggesting a minimal probability of surface transmission in such cases. The new model can serve as a preliminary indicator for identifying different indoor pathogen transmission routes (e.g., food, air, or fomite). Further analyses of pathogens’ transmission routes require additional evidence. Full article

Objectives: Norovirus outbreaks occur in densely populated environments, such as long-term care facilities, hospitals, and schools. On 22 October 2022, an outbreak of acute gastroenteritis was reported at a kindergarten in Korea. An epidemiologic investigation was conducted to identify the source of the infection and prevent further spread. Methods: Rectal swab and environmental samples were collected for bacterial and viral testing. A retrospective cohort study was conducted among 114 kindergarteners at the kindergarten. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated to assess associations of contact with the primary case, as well as food and water consumption. Results: Of the kindergarteners, 28 out of 114 (24.6%) met the case definition. The primary case occurred on 19 October, and subsequent cases began on 21 October. Sharing the same four-year-old class as the primary case (RR, 2.56; 95% CI, 1.35–4.87), being in the same regular class (RR, 2.37; 95% CI, 1.27–4.41), being on the same floor during after-school class (RR, 3.49; 95% CI, 1.74–7.00), and attending the same English class (RR, 1.98; 95% CI, 1.05–3.72) were statistically significant. Consumption of drinking water on the third floor and fourth floor on 20 October had significantly higher and lower RRs, respectively. Norovirus was detected in 9 out of 18 rectal swab samples (50.0%). Conclusions: This norovirus outbreak at the kindergarten was presumed to have been caused by person-to-person transmission from the primary case. Isolation and restriction of symptomatic children in kindergartens should be thoroughly implemented. Additionally, enhanced surveillance among family members of affected individuals is necessary to prevent further outbreaks. Full article

Background/Objectives: Norovirus is a major cause of acute gastroenteritis worldwide. Considering its highly infectious and transmissible nature, rapid and accurate diagnostic tools are of utmost importance for the effective control of outbreaks in the context of point-of-care testing (POCT). In this study, we developed a genogroup-specific multiplex reverse transcriptase loop-mediated isothermal amplification assay to detect the human norovirus genogroups I and II (GI and GII, respectively). Methods: For the comprehensive detection of clinically relevant genotypes, two sets of primers were incorporated into the assays targeting the RdRp-VP1 junction: one against GI.1 and GI.3, and the other for GII.2 and GII.4. Following optimization of the reaction variables, we standardized the reaction conditions at 65 °C with 6 mM MgSO₄, 1.4 mM dNTPs, 7.5 U WarmStart RTx Reverse Transcriptase, and Bst DNA polymerase at 8 U and 10 U for GI and GII, respectively. Amplification was monitored in real-time using a thermocycler platform to ensure precise quantification and detection. Finally, the assay was evaluated through portable isothermal detection device to test its feasibility in on-site settings. Results: Both assays detected the template down to 10²–10³ copies per reaction and showed high target selectivity, yielding no non-specific amplification across 39 enteric pathogens. These assays enabled prompt detection of GI within 10–12 min and of GII within 12–17 min after the reaction was initiated. Onsite validation reveals all template detection below 15 min, demonstrating its potential feasibility in point-of-care applications. Including the sample preparation time, test results were obtained in less than 1 h. Conclusions: This method is a rapid, reliable, and scalable solution for detecting human norovirus in POCT settings for both clinical diagnosis and public health surveillance. Full article