Search Results (55)

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

Group A rotaviruses (RVAs) remain the leading cause of acute gastroenteritis (AGE) in young children in low- and middle-income countries. In Brazil, the oral attenuated RVA vaccine (Rotarix^®), monovalent genotype G1P[8], is distributed by the national immunization program and has drastically reduced morbidity and mortality associated with RVA etiology. In this study, Rotarix^® G1P[8] was detected using specific qRT-PCR from the fecal shedding of children living in the Amazon region, and 18.3% (29/158) were positive and 75.8% (22/29) presented with AGE. The VP4 (VP8*) gene of these sheddings, submitted to Sanger nucleotide sequencing, showed an occurrence of mutations, including the silent mutation at 144C > G (one child) and the following missense mutations— 499T > C (F167L) (two children), 644G > C (C215S) (one child), and 787G > A (E263K) (one child). These mutations had no impact on the protein model structure in silico deduced from the VP4 (VP8*) mutants. The in silico protein model deduced from the VP4 (VP8*) nucleotide sequences, bound to type 1H sugar antigens (H1) and its precursor Lac-para-N-biose (LNB), had a stronger binding to the G1P[8] genotype, when compared to G3P[8]. Rotarix^® shedding was higher in HBGA secretors than in non-secretors (79.3%; 23/29). A total of 11.4% (18/158) of children with Rotarix^® G1P[8] shedding were unvaccinated, indicating the occurrence of indirect protection. Stability evidence of Rotarix^® VP4 (VP8*) spike protein from samples collected in vivo is presented. 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

Post-translational modifications (PTMs) are critically important for protein structure and function, with glycosylation being one of the most common forms of PTM. The gastric pathogen Helicobacter pylori has a general glycosylation system, which performs complex glycosylation of lipopolysaccharide, flagella proteins, and outer membrane proteins (OMPs). One of the best-described OMPs of H. pylori is the blood group binding adhesin (BabA), which interacts with the Lewis histo-blood group antigen, Lewis b. The 3D structure for BabA has been determined, and the ligand specifically described. Although BabA is reported to be a glycoprotein, there are limited data examining the effects of glycosylation on the structure and function of this protein. This study examined the folding and thermostability of non-glycosylated recombinant BabA and used computational approaches to predict the effect of glycosylation on the protein, with a focus on its possible heterologous expression in mammalian cells. Three potential O-linked and three potential N-linked glycosylation sites were predicted. Furthermore, the effect of glycan shielding on the solvent-accessible surface area of BabA was examined. Molecular dynamics simulations highlighted local indicators, including root mean square fluctuation and the number of protein-glycan contacts that were affected by glycosylation. Taken together, the findings support a role of glycans in surface shielding and promoting local stabilization in specific areas of the BabA protein. This study helps to strengthen the understanding of the importance of glycosylation and the role it plays in the structure, function, and stability of H. pylori proteins. 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

Group A rotavirus continues to be a leading global etiological agent of severe gastroenteritis in young children under 5 years of age. The replication of this virus in the host is associated with the occurrence of Lewis antigens and the secretor condition. Moreover, histo-blood group antigens (HBGAs) act as attachment factors to the outer viral protein of VP4 for rotavirus. Therefore, in this study, we employed a metabolomic approach to reveal potential signature metabolic molecules and metabolic pathways specific to rotavirus P[8] strain infection (VP4 genotype), which is associated with the expression of HBGA combined secretor and Lewis (Le) phenotypes, specifically secretor/Le^(a+b+). Further integration of the achieved metabolomics results with lipidomic and proteomics metadata analyses was performed. Saliva samples were collected from children diagnosed as negative or positive for rotavirus P[8] strain infection (VP4 genotype), which is associated with the HBGA combined secretor/Le^(a+b+). A total of 22 signature metabolic molecules that were downregulated include butyrate, putrescine, lactic acid, and 7 analytes. The upregulated metabolic molecule was 2,3-Butanediol. Significant pathway alterations were also specifically observed in various metabolism processes, including galactose and butanoate metabolisms. Butyrate played a significant role in viral infection and was revealed to exhibit different reactions with glycerolipids, glycerophospholipids, sphingolipids, sterol lipids, and fatty acyls. Moreover, butyrate might interact with protein receptors of free fatty acid receptor 2 (FFAR2) and free fatty acid receptor 3 (FFAR3). The revealed metabolic pathways and molecule might provide fundamental insight into the status of rotavirus P[8] strain infection for monitoring its effects on humans. Full article

Recently, using a panel of recombinant CHO cell lines, we identified the coxsackie and adenovirus receptor (CAR) and histo-blood group antigens (HBGAs) or sialic acid as the minimum requirement for susceptibility to rhesus enteric calicivirus (ReCV) infections. While ReCVs cause lytic infection in LLC-MK2 cells, recombinant CHO (rCHO) cell lines did not exhibit any morphological changes upon infection. To monitor infectious virus production, rCHO cell cultures had to be freeze–thawed and titrated on LLC-MK2 monolayers. This raised the question of whether ReCV infection in rCHO cells is persistent and whether non-enveloped progeny virions are released from the infected cells. Here, we used the rCHO-CAR+ cell line and a CAR and sialic acid-dependent recovirus strain (FT7) and found that these cells were persistently infected, and infectious virus was continuously produced and released into the culture without showing any visible cell damage. Viral capsid protein and replication intermediate double-stranded RNA (dsRNA) were detectable in almost all cells for at least 12 passages. We suspect a fully exosomal viral exit mechanism without a lytic cycle in these cells. rCHO cell may provide a valuable system for ReCV production (producer cell line) and serve as a model for investigating enteric calicivirus non-lytic viral exit mechanisms and the properties of the released, most likely membrane-cloaked, infectious progeny virions. Full article

The suboptimal performance of rotavirus (RV) vaccines in developing countries and in animals necessitates further research on the development of novel therapeutics and control strategies. To initiate infection, RV interacts with cell-surface O-glycans, including histo-blood group antigens (HBGAs). We have previously demonstrated that certain non-pathogenic bacteria express HBGA^- like substances (HBGA⁺) capable of binding RV particles in vitro. We hypothesized that HBGA⁺ bacteria can bind RV particles in the gut lumen protecting against RV species A (RVA), B (RVB), and C (RVC) infection in vivo. In this study, germ-free piglets were colonized with HBGA⁺ or HBGA^- bacterial cocktail and infected with RVA/RVB/RVC of different genotypes. Diarrhea severity, virus shedding, immunoglobulin A (IgA) Ab titers, and cytokine levels were evaluated. Overall, colonization with HBGA⁺ bacteria resulted in reduced diarrhea severity and virus shedding compared to the HBGA^- bacteria. Consistent with our hypothesis, the reduced severity of RV disease and infection was not associated with significant alterations in immune responses. Additionally, colonization with HBGA⁺ bacteria conferred beneficial effects irrespective of the piglet HBGA phenotype. These findings are the first experimental evidence that probiotic performance in vivo can be improved by including HBGA⁺ bacteria, providing decoy epitopes for broader/more consistent protection against diverse RVs. Full article

The ABO blood groups, Lewis antigens, and secretor systems are important components of transfusion medicine. These interconnected systems have been also shown to be associated with differing susceptibility to bacterial and viral infections, likely as the result of selection over the course of evolution and the constant tug of war between humans and infectious microbes. This comprehensive narrative review aimed to explore the literature and to present the current state of knowledge on reported associations of the ABO, Lewis, and secretor blood groups with SARS-CoV-2 infection and COVID-19 severity. Our main finding was that the A blood group may be associated with increased susceptibility to SARS-CoV-2 infection, and possibly also with increased disease severity and overall mortality. The proposed pathophysiological pathways explaining this potential association include antibody-mediated mechanisms and increased thrombotic risk amongst blood group A individuals, in addition to altered inflammatory cytokine expression profiles. Preliminary evidence does not support the association between ABO blood groups and COVID-19 vaccine response, or the risk of developing long COVID. Even though the emergency state of the pandemic is over, further research is needed especially in this area since tens of millions of people worldwide suffer from lingering COVID-19 symptoms. Full article

Human noroviruses (HuNoVs) are a major cause of acute gastroenteritis, contributing significantly to annual foodborne illness cases. However, studying these viruses has been challenging due to limitations in tissue culture techniques for over four decades. Tulane virus (TV) has emerged as a crucial surrogate for HuNoVs due to its close resemblance in amino acid composition and the availability of a robust cell culture system. Initially isolated from rhesus macaques in 2008, TV represents a novel Calicivirus belonging to the Recovirus genus. Its significance lies in sharing the same host cell receptor, histo-blood group antigen (HBGA), as HuNoVs. In this study, we introduce, through cryo-electron microscopy (cryo-EM), the structure of a specific TV variant (the 9-6-17 TV) that has notably lost its ability to bind to its receptor, B-type HBGA—a finding confirmed using an enzyme-linked immunosorbent assay (ELISA). These results offer a profound insight into the genetic modifications occurring in TV that are necessary for adaptation to cell culture environments. This research significantly contributes to advancing our understanding of the genetic changes that are pivotal to successful adaptation, shedding light on fundamental aspects of Calicivirus evolution. Full article

Rotavirus (RV) is the leading cause of acute gastroenteritis (AGE) in children under 5 years old worldwide, and several studies have demonstrated that histo–blood group antigens (HBGAs) play a role in its infection process. In the present study, human stool filtrates from patients diagnosed with RV diarrhea (genotyped as P[8]) were used to infect differentiated Caco-2 cells (dCaco-2) to determine whether such viral strains of clinical origin had the ability to replicate in cell cultures displaying HBGAs. The cell culture-adapted human RV Wa model strain (P[8] genotype) was used as a control. A time-course analysis of infection was conducted in dCaco-2 at 1, 24, 48, 72, and 96 h. The replication of two selected clinical isolates and Wa was further assayed in MA104, undifferentiated Caco-2 (uCaco-2), HT29, and HT29-M6 cells, as well as in monolayers of differentiated human intestinal enteroids (HIEs). The results showed that the culture-adapted Wa strain replicated more efficiently in MA104 cells than other utilized cell types. In contrast, clinical virus isolates replicated more efficiently in dCaco-2 cells and HIEs. Furthermore, through surface plasmon resonance analysis of the interaction between the RV spike protein (VP8*) and its glycan receptor (the H antigen), the V7 RV clinical isolate showed 45 times better affinity compared to VP8* from the Wa strain. These findings support the hypothesis that the differences in virus tropism between clinical virus isolates and RV Wa could be a consequence of the different HBGA contents on the surface of the cell lines employed. dCaco-2, HT29, and HT29M6 cells and HIEs display HBGAs on their surfaces, whereas MA104 and uCaco-2 cells do not. These results indicate the relevance of using non-cell culture-adapted human RV to investigate the replication of rotavirus in relevant infection models. Full article

Noroviruses (NoVs) are major foodborne pathogens that cause acute gastroenteritis. Oysters are significant carriers of this pathogen, and disease transmission from the consumption of NoVs-infected oysters occurs worldwide. The review discusses the mechanism of NoVs bioaccumulation in oysters, particularly the binding of histo-blood group antigen-like (HBGA-like) molecules to NoVs in oysters. The review explores the factors that influence NoVs bioaccumulation in oysters, including temperature, precipitation and water contamination. The review also discusses the detection methods of NoVs in live oysters and analyzes the inactivation effects of high hydrostatic pressure, irradiation treatment and plasma treatment on NoVs. These non-thermal processing treatments can remove NoVs efficiently while retaining the original flavor of oysters. However, further research is needed to reduce the cost of these technologies to achieve large-scale commercial applications. The review aims to provide novel insights to reduce the bioaccumulation of NoVs in oysters and serve as a reference for the development of new, rapid and effective methods for detecting and inactivating NoVs in live oysters. Full article

Sapoviruses, like noroviruses, are single-stranded positive-sense RNA viruses classified in the family Caliciviridae and are recognized as a causative pathogen of diarrhea in infants and the elderly. Like human norovirus, human sapovirus (HuSaV) has long been difficult to replicate in vitro. Recently, it has been reported that HuSaV can be replicated in vitro by using intestinal epithelial cells (IECs) derived from human tissues and cell lines derived from testicular and duodenal cancers. In this study, we report that multiple genotypes of HuSaV can sufficiently infect and replicate in human-induced pluripotent stem cell-derived IECs. We also show that this HuSaV replication system can be used to investigate the conditions for inactivation of HuSaV by heat and alcohol, and the effects of virus neutralization of antisera obtained by immunization with vaccine antigens, under conditions closer to the living environment. The results of this study confirm that HuSaV can also infect and replicate in human normal IECs regardless of their origin and are expected to contribute to future virological studies. Full article

Live-attenuated, oral rotavirus vaccines have significantly reduced rotavirus-associated diarrhoea morbidity and infant mortality. However, vaccine immunogenicity is diminished in low-income countries. We investigated whether maternal and infant intrinsic susceptibility to rotavirus infection via histo-blood group antigen (HBGA) profiles influenced rotavirus (ROTARIX^®) vaccine-induced responses in Zambia. We studied 135 mother–infant pairs under a rotavirus vaccine clinical trial, with infants aged 6 to 12 weeks at pre-vaccination up to 12 months old. We determined maternal and infant ABO/H, Lewis, and secretor HBGA phenotypes, and infant FUT2 HBGA genotypes. Vaccine immunogenicity was measured as anti-rotavirus IgA antibody titres. Overall, 34 (31.3%) children were seroconverted at 14 weeks, and no statistically significant difference in seroconversion was observed across the various HBGA profiles in early infant life. We also observed a statistically significant difference in rotavirus-IgA titres across infant HBGA profiles at 12 months, though no statistically significant difference was observed between the study arms. There was no association between maternal HBGA profiles and infant vaccine immunogenicity. Overall, infant HBGAs were associated with RV vaccine immunogenicity at 12 months as opposed to in early infant life. Further investigation into the low efficacy of ROTARIX^® and appropriate intervention is key to unlocking the full vaccine benefits for U5 children. Full article

Noroviruses, the major cause of acute viral gastroenteritis, are known to bind to histo-blood group antigens (HBGAs), including ABH groups and Lewis-type epitopes, which decorate the surface of erythrocytes and epithelial cells of their host tissues. The biosynthesis of these antigens is controlled by several glycosyltransferases, the distribution and expression of which varies between tissues and individuals. The use of HBGAs as ligands by viruses is not limited to humans, as many animal species, including oysters, which synthesize similar glycan epitopes that act as a gateway for viruses, become vectors for viral infection in humans. Here, we show that different oyster species synthesize a wide range of N-glycans that share histo-blood A-antigens but differ in the expression of other terminal antigens and in their modification by O-methyl groups. In particular, we show that the N-glycans isolated from Crassostrea gigas and Ostrea edulis exhibit exquisite methylation patterns in their terminal N-acetylgalactosamine and fucose residues in terms of position and number, adding another layer of complexity to the post-translational glycosylation modifications of glycoproteins. Furthermore, modeling of the interactions between norovirus capsid proteins and carbohydrate ligands strongly suggests that methylation has the potential to fine-tune the recognition events of oysters by virus particles. Full article