Search Results (172)

Human astroviruses are small, non-enveloped RNA viruses belonging to the family Astroviridae. Among the four species known to infect humans, the species Mamastrovirus hominis (the classical human astroviruses, formerly MAstV1) is associated with gastrointestinal illness worldwide, while three more recently identified species have been linked to lethal central nervous system infections. High substitution rates and recombination drive their rapid evolution, yet recombination patterns in classical human astroviruses remain poorly characterized. This study systematically analyzes patterns and temporal dynamics of natural recombination in classical human astroviruses. Publicly available genomes of classical human astroviruses were analyzed to identify recombination hotspots. Recombinant forms were defined as stable phylogenetic lineages unaffected by recombination, and their half-lives were estimated based on time-scaled phylogenies (BEAST2v2.7.7). Recombination in classical human astroviruses occurred most frequently at the ORF1b/ORF2 junction, but also within ORF1a, at the ORF1a/ORF1b junction, and within ORF2. Only the 3′-part of ORF1a and a fragment of ORF1b exhibited robust temporal signal, yielding substitution rates of 2.35 × 10⁻³ and 2.14 × 10⁻³ s/s/y, respectively. The half-lives of recombinant forms varied considerably by genomic region: longest for exchanges between the parts of ORF1a (21 years), intermediate for ORF1a/ORF1b recombinants (7–9 years), and shortest for ORF1ab/ORF2 recombinants (2.5–3.6 years). The estimated half-lives for recombinants align with those reported for human enteroviruses and noroviruses. These findings highlight the dynamics of the generation of astrovirus diversity and may inform advanced surveillance of emerging strains. Full article

The family Caliciviridae encompasses a diverse group of non-enveloped, positive-sense RNA viruses that are significant pathogens in veterinary medicine. This narrative review summarizes the current state of knowledge regarding the clinical, molecular, and epidemiological features of the three calicivirus genera identified in bovine hosts: Norovirus, Nebovirus, and Vesivirus. Bovine noroviruses and neboviruses are neglected enteric pathogens, frequently detected in association with neonatal calf diarrhea and often present in co-infections with other enteric agents. Clinical presentations for these enteric viruses range from severe, watery diarrhea to asymptomatic shedding, with distinct pathogenic profiles observed between norovirus genotypes GIII.1 and GIII.2. In contrast, the genus Vesivirus exhibits a broad host range, and bovine vesivirus strains are phylogenetically linked to vesiviruses identified in pigs and marine animals. Bovine vesivirus infections are associated with a broader spectrum of clinical manifestations, including respiratory disease, vesicular lesions, and abortion. Serological and virological surveys indicate that exposure to these viruses is ubiquitous in cattle populations globally. While direct evidence of human infection by bovine noroviruses and neboviruses remains limited, vesiviruses possess a confirmed capacity for cross-species transmission to humans. Significant knowledge gaps remain, particularly regarding in vitro culture systems, necessitating further research to facilitate vaccine development and clarify transmission dynamics. Full article

Polyethylene Glycol (PEG) precipitation and Nanotrap^® Microbiome Particles (NMP) are widely used methods for concentrating viruses in wastewater due to their simplicity, cost-effectiveness, efficiency, and rapid turnaround time. This study compared the performance of these methods in detecting noroviruses (GI and GII) and SARS-CoV-2 collected from two wastewater treatment facilities using quantitative PCR. Norovirus was detected in all samples (23/23) using both protocols, but PEG yielded higher mean concentrations for GI and GII than NMP, indicating improved quantitative recovery for non-enveloped viruses. For SARS-CoV-2, NMP showed significantly higher positive ratios for the N2 gene (Fisher’s Exact Test, p < 0.01), but no significant difference was observed for the N1 gene (p > 0.05), indicating comparable performance between the methods for this target. These findings highlight PEG’s effectiveness for non-enveloped viruses and NMP’s suitability for enveloped viruses, emphasizing the importance of selecting virus concentration methods based on viral structure. This study provides a framework for optimizing wastewater-based epidemiology (WBE) protocols and enhancing public health surveillance for diverse viral targets. Future research should focus on refining these methodologies and exploring their applicability to other viral pathogens to enhance public health surveillance frameworks. Full article

Background: Human noroviruses are the leading cause of foodborne gastroenteritis worldwide. Accumulating evidence suggests that food matrices containing fucosylated or histo-blood group antigen (HBGA)-like glycans may facilitate viral attachment and persistence, yet the molecular mechanisms underlying these interactions remain unclear. Methods: In this study, we performed a comparative computational analysis of norovirus–glycan interactions by integrating AlphaFold3-based structure prediction, molecular docking, and molecular dynamics simulations. A total of 182 P-domain models representing all genotypes across five human norovirus genogroups (GI, GII, GIV, GVIII, and GIX) were predicted and docked with a lettuce-derived core-fucosylated hexasaccharide (H₂N₂F₂) previously identified by our group. The three complexes exhibiting the most favorable docking energies were further examined using 40 ns molecular dynamics simulations, followed by MM/GBSA binding free energy calculations and per-residue decomposition analyses. Results: Docking results indicated that the majority of modeled P proteins were able to adopt energetically favorable interaction poses with H₂N₂F₂, with predicted binding energies ranging from −3.7 to −7.2 kcal·mol⁻¹. The most favorable docking energies were observed for GII.6_S9c_KC576910 (−7.2 kcal·mol⁻¹), GII.3_MX_U22498 (−7.1 kcal·mol⁻¹), and GII.4_CARGDS11182_OR700741 (−6.8 kcal·mol⁻¹). Molecular dynamics simulations suggested stable ligand engagement within canonical HBGA-binding pockets, with recurrent residues such as Asp374, Gln393, and Arg345 contributing to electrostatic and hydrophobic interactions, consistent with previously reported HBGA-binding motifs. MM/GBSA analyses revealed comparatively favorable binding tendencies among these complexes, particularly for globally prevalent genotypes including GII.3, GII.4, and GII.6. Conclusions: This work provides a large-scale structural and energetic assessment of the potential interactions between a naturally occurring lettuce-derived fucosylated hexasaccharide and human norovirus P domains. The results support the notion that core-fucosylated food-associated glycans can serve as interaction partners for diverse norovirus genotypes and offer comparative molecular insights into glycan recognition patterns relevant to foodborne transmission. The integrative AlphaFold3–docking–dynamics framework presented here may facilitate future investigations of virus–glycan interactions within food matrices. Full article

Background: Norovirus is a leading cause of epidemic acute gastroenteritis worldwide, associated with significant morbidity, mortality, and economic loss. Despite its global impact, no licensed vaccine is currently available, and vaccine development remains challenging. Methods: We explored avian immunoglobulin Y (IgY) antibodies as a low-cost countermeasure against norovirus infection. We generated recombinant protruding (P) domain proteins from the capsid protein (VP1) of noroviruses, representing two GII.4 variants and the GII.6 genotype. These were combined into a single immunogen to immunize laying hens to produce norovirus VP1-specific IgY antibodies. Results: Immunization of laying hens with the P domain proteins elicited high-titer (>1:450,000) P domain-specific IgY antibodies. The yolk-derived IgY effectively inhibited binding of various norovirus P particles to their histo-blood group antigen ligands, with 50% blocking titers (BT50) up to 1:8533 against homotypic GII.4 and 1:667 against heterotypic G1.1 Norwalk virus P particles. Importantly, the IgY neutralized replication of GII.4 norovirus in the human intestinal enteroid (HIE) system at a high titer of over 1:2500, equivalent to 0.70 µg/mL of total IgY. We also produced norovirus shell (S) domain proteins and corresponding IgY antibodies, which neutralized GII.4 norovirus replication in the HIE model at a titer of ~1:800, equivalent to 2.98 µg/mL of total IgY. This provides the first evidence that the S domain contains neutralizing epitopes. Conclusions: Our findings support the potential of IgY targeting norovirus P or S domains as a scalable, cost-effective strategy for preventing norovirus infection and disease. Full article

Noroviruses are a leading cause of acute gastroenteritis worldwide, with a particularly high burden among children under five years of age. We analyzed nationwide surveillance data from EnterNet-Korea collected between 2019 and 2024—covering both the pre- and post-COVID-19 pandemic periods—to assess norovirus detection rates and genotype distribution. Noroviruses were detected by RT-qPCR, and dual genotyping of capsid (G) and polymerase (P) types was performed by sequencing the ORF1–2 junction region. Among the 67,159 specimens tested, 8.4% (n = 5652) were norovirus-positive, with the highest prevalence observed in children aged 0–5 years (19.9%). In this age group, genotyping was successful in 72.4% (2633/3635) of positive cases, identifying 30 distinct genotypes (GI: 9; GII: 21). The most common strains were GII.4[P31] (38.1%), GII.4[P16] (27.1%), and GII.2[P16] (10.4%), with substantial year-to-year variation. Notably, the emergence of GII.17[P17] in late 2024 indicates shifting genotype dynamics, underscoring the need for strengthened surveillance and reconsideration of vaccine strain selection. To our knowledge, this is the first nationwide dual-typing study in Korea encompassing the COVID-19 pandemic era. These findings provide essential baseline data for integration into global surveillance systems and inform future vaccine development and public health strategies. Full article

Wastewater-based epidemiology (WBE) is an effective tool for assessing health risks in rural areas with limited access to health care. Wastewater treatment plants (WWTPs) allow for the monitoring of pathogenic microorganisms, which is key to detecting viral integrity and bacterial viability to assess health risks. This study evaluated five rural WWTPs in Chile during 2022 in two seasons (autumn–winter and spring–summer). SARS-CoV-2, norovirus GI/GII, and HAdV-F40/41 was analyzed, along with antibiotic-resistant coliforms. Influent and effluent samples were used, with viral integrity analysis by propidium monoazide and culture methods to assess bacterial resistance. Despite the low number of clinical cases, SARS-CoV-2 was detected in all influent samples. Intact viral particles of NoV GI (78%), NoV GII (72%), and HAdV-F40/41 (65%) were found. This suggests that they may still be infectious. Viral removal ranged from 74% to 100%, although intact HAdV was detected in effluent (6.2%). Coliforms resistant to various antibiotics were detected and partially removed (22–100%). Removal efficiency depends on the type of treatment and the season of the year. WWTPs act as temporary reservoirs of infectious agents. This study reinforces the usefulness of WBE in rural contexts and WWTPs as barriers or not to these contaminants to the environment. 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

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

Human noroviruses (HuNoVs) are the primary cause of acute viral gastroenteritis. There are no antivirals or vaccines available to treat and/or prevent HuNoV. Norovirus 3C-like protease (3CLpro) is essential for viral replication; consequently, the inhibition of this enzyme is a fruitful avenue for antinorovirus therapeutics. To discover novel 3CLpro inhibitors with diverse scaffolds, a multi-stage virtual screening approach was performed by docking >10 million compounds into the 3CLpro catalytic site. An initial subset of 18 compounds was selected, and compounds YY-1029 and YY-4204 were identified as the best two molecules. Molecular dynamics (MD) simulations and binding free energy calculations (MM/GBSA) of YY-1029 and YY-4204 were performed to elucidate the binding mechanisms. The ADMET properties were also estimated to predict the potential druggability of representative molecules. All 18 compounds were evaluated for their antinorovirus activity and cytotoxicity in a cell-based replicon system. This work could provide information for the development of 3CL pro inhibitors. Full article

Enteric pathogens remain a health threat for children in low-income countries. A single nucleotide polymorphism (SNP) in the FUT2 gene that precludes the expression of fucosyltransferase 2 has been reported to influence the susceptibility to rotavirus and norovirus infections. The aim of this study was to investigate the association between G428A at rs601338 (stop codon variant) in the FUT2 gene and a range of enteric pathogens in children under 5 years of age. Rectal swab samples from 668 children (median age 13.6 months, 51% males, 93% rotavirus vaccinated, 468 with diarrhea) from Rwanda were analyzed via PCR for pathogen detection and SNP genotyping. A FUT2 stop codon (‘non-secretor’ status) was found in 19% of all children. Rotavirus was detected in 5.3% of non-secretors compared with in 13% of secretors (OR = 0.39, p = 0.019). Rotavirus P[8] was the predominant genotype and was found in 2.3% of non-secretors compared with 8.8% of secretors (p = 0.009). There was no association with any other pathogen, including noroviruses, of which 2 of 14 GII.4 infections were detected among non-secretors. Thus, the FUT2 stop codon variant was associated with rotavirus but not with any other pathogen. Full article

In the mid-1970s, it was revealed that the 5′ end of the RNA genome of poliovirus (PV) was covalently linked to a peptide called VPg (viral protein, genome-linked). Subsequently, VPgs have been found attached to many other viruses and even phages. This review summarizes the patterns of physicochemical properties that are conserved within the VPgs of plus-strand RNA viruses where short-peptide VPgs have been identified. Mutagenesis and structural data indicate the importance of a 5 aa conserved motif at the N-termini of picornaviral VPgs (around the tyrosine 3 residue, which forms a covalent bond to UMP and the RNA). Hidden Markov models have been used to find motifs and VPgs in additional genera of picornaviruses, as well as dicistroviruses in insects and comoviruses in plants. These latter VPgs are bound to the RNA termina through linkages to serine or threonine. The role of free VPg and VPgpU needs clarification, especially in light of multiple genome copies in many of the viruses. Lysine and other positively charged side chains are hallmarks of VPgs. These may contribute to interactions with the viral RNA, polymerase, membranes and cellular proteins. The larger protein VPgs from potyviruses and noroviruses/caliciviruses may also show some areas of similar properties to these small peptides. Full article

Quantitative Polymerase Chain Reaction (qPCR) is a molecular technique that has become a gold standard in various disciplines, including environmental microbiology, due to its high sensitivity and specificity. In recent years, it has been extensively used in wastewater-based epidemiology to monitor the prevalence of different viruses in the population. In this study, we evaluated whether the no inclusion of a standard curve in each single experiment to reduce time and costs could have an impact on the accuracy of the results. Thirty independent RT-qPCR standard curve experiments using quantitative synthetic RNA material were conducted for seven different viruses, which include two targets of the novel SARS-CoV-2, hepatitis A and E, noroviruses genogroups I and II, human astrovirus, and rotavirus. Results showed that although all the viruses presented adequate efficiency rates (>90%), variability was also observed between them, independently of the viral concentration tested. NoVGII was the virus that presented the higher inter-assay variability in terms of efficiency while showing better sensitivity. In terms of heterogeneity in results, the two targets of SARS-CoV-2 showed the highest rates, being N2 the gene that presented the largest variability (CV 4.38–4.99%) and the lowest efficiency (90.97%). These findings indicate that including a standard curve in every experiment is recommended to obtain reliable results. Full article

Noroviruses are a major cause of acute gastroenteritis, often transmitted through contaminated food and water. In this study, lemon juice (LJ), rich in citric acid (CA) and flavonoids, was tested against Feline Calicivirus (FCV), used as a surrogate of human norovirus. Significant virucidal activity was observed for pure LJ (pH = 2.3), with a reduction in viral titers as high as 4.50 log₁₀ TCID₅₀/50 µL after 30 s and complete inactivation after 1 min. LJ also showed limited virucidal activity at a dilution of 1:2000 (pH = 6.7), with a reduction in viral titer of 0.75 log₁₀ TCID₅₀/50 µL. CA (at the same molarity as CA in pure LJ and adjusted to pH = 2.3) exhibited virucidal effects comparable to pure LJ, with a decrease in viral titers as high as 3.75 log₁₀ TCID₅₀/50 µL, whilst diluted CA (pH = 6.7) did not show significant effects. This study demonstrated the virucidal efficacy of LJ, suggesting the role of pH and, eventually, of LJ bioactive compounds against a norovirus surrogate. Due to its large use in food preparation, LJ has the potential to enhance the safety of raw food. Also, broader applications in personal hygiene and surface disinfection could be devised. Full article