Correlates of Rotavirus Vaccine Shedding and Seroconversion in a US Cohort of Healthy Infants.

BACKGROUND: Rotavirus is a leading cause of severe pediatric gastroenteritis; 2 highly effective vaccines are used in the United States (US). We aimed to identify correlates of immune response to rotavirus vaccination in a US cohort. METHODS: Pediatric Respiratory and Enteric Virus Acquisition and Immunogenesis Longitudinal (PREVAIL) is a birth cohort of 245 mother-child pairs enrolled in 2017-2018 and followed for 2 years. Infant stool samples and symptom information were collected weekly. Shedding was defined as reverse-transcription polymerase chain reaction detection of rotavirus vaccine virus in stools collected 4-28 days after dose 1. Seroconversion was defined as a 3-fold rise in immunoglobulin A between the 6-week and 6-month blood draws. Correlates were analyzed using generalized estimating equations and logistic regression. RESULTS: Prevaccination immunoglobulin G (IgG) (odds ratio [OR], 0.84 [95% confidence interval {CI}, .75-.94] per 100-unit increase) was negatively associated with shedding. Shedding was also less likely among infants with a single-nucleotide polymorphism inactivating FUT2 antigen secretion ("nonsecretors") with nonsecretor mothers, versus all other combinations (OR, 0.37 [95% CI, .16-.83]). Of 141 infants with data, 105 (74%) seroconverted; 78 (77%) had shed vaccine virus following dose 1. Prevaccination IgG and secretor status were significantly associated with seroconversion. Neither shedding nor seroconversion significantly differed by vaccine product. CONCLUSIONS: In this US cohort, prevaccination IgG and maternal and infant secretor status were associated with rotavirus vaccine response.

Histo-Blood Group Antigen Null Phenotypes Associated With a Decreased Risk of Clinical Rotavirus Vaccine Failure Among Children <2 Years of Age Participating in the Vaccine Impact on Diarrhea in Africa (VIDA) Study in Kenya, Mali, and the Gambia.

BACKGROUND: Previously studied risk factors for rotavirus vaccine failure have not fully explained reduced rotavirus vaccine effectiveness in low-income settings. We assessed the relationship between histo-blood group antigen (HBGA) phenotypes and clinical rotavirus vaccine failure among children <2 years of age participating in the Vaccine Impact on Diarrhea in Africa Study in 3 sub-Saharan African countries. METHODS: Saliva was collected and tested for HBGA phenotype in children who received rotavirus vaccine. The association between secretor and Lewis phenotypes and rotavirus vaccine failure was examined overall and by infecting rotavirus genotype using conditional logistic regression in 218 rotavirus-positive cases with moderate-to-severe diarrhea and 297 matched healthy controls. RESULTS: Both nonsecretor and Lewis-negative phenotypes (null phenotypes) were associated with decreased rotavirus vaccine failure across all sites (matched odds ratio, 0.30 [95% confidence interval: 0.16-0.56] or 0.39 [0.25-0.62], respectively]. A similar decrease in risk against rotavirus vaccine failure among null HBGA phenotypes was observed for cases with P[8] and P[4] infection and their matched controls. While we found no statistically significant association between null HBGA phenotypes and vaccine failure among P[6] infections, the matched odds ratio point estimate for Lewis-negative individuals was >4. CONCLUSIONS: Our study demonstrated a significant relationship between null HBGA phenotypes and decreased rotavirus vaccine failure in a population with P[8] as the most common infecting genotype. Further studies are needed in populations with a large burden of P[6] rotavirus diarrhea to understand the role of host genetics in reduced rotavirus vaccine effectiveness.

Structural Insight into Terminal Galactose Recognition by Two Non-HBGA Binding GI.3 Noroviruses.

Human noroviruses (huNoVs) cause epidemic acute gastroenteritis using histo-blood group antigens (HBGAs) as host receptors or attachment factors to initiate an infection. While most huNoVs have been shown to bind HBGAs, some known clinical isolates, such as GI.3 DSV and VA115, do not recognize any HBGAs and thus the molecular mechanism behind their infections remains elusive. In this study, we provided both phenotypic and structural evidence to show that huNoV DSV and VA115 recognize a group of glycans with terminal galactoses as ligands. First, through glycan array we found that both DSV and VA115 protruding (P) domain proteins bound two oligosaccharides that share common terminal galactoses. Then, by determination of the crystal structures of DSV/VA115 P proteins in complex with Galα1-3Galß1-4Glc and/or NA2 N-Glycan, respectively, we showed that the terminal galactose is the main saccharide recognized by the two viral proteins. Our data demonstrated that GI huNoVs can interact with non-HBGA glycans through their conserved galactose binding site, shedding light on the mechanism of huNoV adaptation through recognizing new glycan receptors to facilitate their widespread nature in human population. These findings are also of significance in strategy development for huNoV control and prevention, as well as development of antiviral drugs. IMPORTANCE Human noroviruses (huNoVs) are the most important viral pathogens causing epidemic acute gastroenteritis worldwide. Previous studies indicated that histo-blood group antigens (HBGAs) are critical host-susceptibility factors affecting huNoV host susceptibility, host range, and probably prevalence. However, certain huNoVs, such as GI.3 DSV and VA115, do not recognize any HBGAs. This implies that other unknown host factors might exist and the molecular mechanism underlying their host receptor recognition or attachment remains elusive. In this study, we found that purified capsid protruding domain proteins from two GI.3 huNoVs specifically bind two glycans that contain a common terminal galactose. We solved the crystal structures of the complexes at atomic resolution and validated the vital amino acids involved in glycan recognition. Our findings elucidate the mechanism of GI.3 huNoV-non-HBGA glycan interaction, which explains why GI.3 virus strains could not bind human HBGAs, paving a way to the prevention and treatment of huNoV-associated diseases.

Intestinal Norovirus Binding Patterns in Nonsecretor Individuals.

Human norovirus (HuNoV) infection is associated with an active FUT2 gene, which characterizes the secretor phenotype. However, nonsecretor individuals are also affected by HuNoV infection although in a lesser proportion. Here, we studied GII.3, GII.4, and GII.17 HuNoV interactions in nonsecretor individuals using virus-like particles (VLPs). Only GII.4 HuNoV specifically interacted with nonsecretor saliva. Competition experiments using histo-blood group antigen (HBGA)-specific monoclonal antibodies (MAbs) demonstrate that GII.4 VLPs recognized the Lewis a (Lea) antigen. We also analyzed HuNoV VLP interactions on duodenum tissue blocks from healthy nonsecretor individuals. VLP binding was observed for the three HuNoV genotypes in 10 of the 13 individuals, and competition experiments demonstrated that VLP recognition was driven by an interaction with the Lea antigen. In 3 individuals, binding was restricted to either GII.4 alone or GII.3 and GII.17. Finally, we performed a VLP binding assay on proximal and distal colon tissue blocks from a nonsecretor patient with Crohn's disease. VLP binding to inflammatory tissues was genotype specific since GII.4 and GII.17 VLPs were able to interact with regenerative mucosa, whereas GII.3 VLP was not. The binding of GII.4 and GII.17 HuNoV VLPs was linked to Lea in regenerative mucosae from the proximal and distal colon. Overall, our data clearly showed that Lea has a pivotal role in the recognition of HuNoV in nonsecretors. We also showed that Lea is expressed in inflammatory/regenerative tissues and interacts with HuNoV in a nonsecretor individual. The physiological and immunological consequences of such interactions in nonsecretors have yet to be elucidated. IMPORTANCE Human norovirus (HuNoV) is the main etiological agent of viral gastroenteritis in all age classes. HuNoV infection affects mainly secretor individuals where ABO(H) and Lewis histo-blood group antigens (HBGAs) are present in the small intestine. Nonsecretor individuals, who only express Lewis (Le) antigens, are less susceptible to HuNoV infection. Here, we studied the interaction of common HuNoV genotypes (GII.3, GII.4, and GII.17) in nonsecretor individuals using synthetic viral particles. Saliva binding assays showed that only GII.4 interacted with nonsecretor saliva via the Lewis a (Lea) antigen Surprisingly, the three genotypes interacted with nonsecretor enterocytes via the Lea antigen on duodenal tissue blocks, which were more relevant for HuNoV/HBGA studies. The Lea antigen also played a pivotal role in the recognition of GII.4 and GII.17 particles by inflammatory colon tissue from a nonsecretor Crohn's disease patient. The implications of HuNoV binding in nonsecretors remain to be elucidated in physiological and pathological conditions encountered in other intestinal diseases.

Circulating rotavirus P[8]-lineage IV, unlike P[8]-lineage III, significantly related to nonsecretors status in Iranian children.

Rotavirus (RV) P[8] strains are responsible for the most of the RV infections globally and are significantly associated with the secretor and Lewis positive status. Among the distinct P[8] lineages, different ligand affinities have been detected which can be linked to differences in secretor status associated histo-blood group antigens (HBGAs). Herein, we report the lineages of P[8] strains and their associated secretor and Lewis antigen phenotypes in Iranian children. The phylogenetic tree and sequence analyses showed that the most common detected RV P[8] strain belonged to P[8]-lineage III (92%) and were significantly associated with secretor and Lewis positive status. In contrast, 8% of P[8] strains clustered into the P[8]-lineage IV and were significantly associated with nonsecretor status, implying that lineage IV tends to infect nonsecretor individuals. Furthermore, protein modeling and amino acid analyses of the VP8* glycan binding site of Iranian P[8]-lineage IV strains indicated two residual substitutions (T184V and N216V/I) compared to the P[8]-lineage III strains that might have affected the glycan affinity among P[8]-lineages IV strains. The corresponding residual changes might permit their continued transmission in nonsecretor children in competition with other P[8]-lineages. Although nonsecretors show natural resistant to P[8] strains, but such residual changes might overcome this natural resistance which in turn might indirectly contribute to the decline in the vaccine efficacy in populations where HBGA polymorphism allows their circulation at high frequency.

Soluble extracellular polymeric substance (SEPS) of histo-blood group antigen (HBGA) expressing bacterium Sphingobacterium sp. SC015 influences the survival and persistence of norovirus on lettuce.

Foodborne norovirus (NoV) outbreaks linked to leafy greens are common due to a lack of efficient strategies to prevent NoV spread from contaminated surfaces. We previously found that Sphingobacterium sp. SC015 in lettuce phyllosphere expresses histo-blood group antigen (HBGA)-like substances in soluble extracellular polymeric substances (SEPS) that contribute to NoV adherence on lettuce. Here, we extracted SEPS from bacterium SC015 (SEPS-SC015), analyzed their chemical composition, and examined their roles in the survival and protection of NoV and surrogates [murine norovirus (MNV-1) and Tulane virus (TuV)] on lettuce. Presence of SEPS-SC015 significantly increased survival and persistence of human NoV (HuNoV), MNV-1, and TuV at days 7 and 14, compared with virus alone. HuNoV, TuV, and MNV-1 seeded with SEPS-SC015 were more resistant to heat (70 °C, 2 min) than these viruses alone. SEPS-SC015 also increased viral resistance to sodium hypochlorite inactivation by treatment with 30 and 300 ppm bleach at 26 °C for 10 min. However, SEPS-SC015 was not effective at protecting these viruses under UV inactivation. Binding of TuV to SC015 bacteria and SEPS-SC015, visualized using transmission electron microscopy, suggests that protection might be related to direct interaction between SEPS-SC015 and viral particles. This study provides important insights that will help inform strategies to improve food safety.

The endemic GII.4 norovirus-like-particle induced-antibody lacks of cross-reactivity against the epidemic GII.17 strain.

Norovirus-like particle (VLP) vaccine is promising against human norovirus infection. Unfortunately, genetic diversity of norovirus hindered the development of this vaccine. In this study, the immunogenicity of norovirus VLPs induced by the endemic GII.4 and the epidemic GII.17 genotypes, and the cross-reactivity between them as well as GI.1 and GII.3 VLPs were evaluated in mice by using serum IgG and histo-blood group antigen (HBGA) blocking antibodies as index. Results showed well immunogenicity of both GII.4 and GII.17 VLPs in mice. Serum IgG GMT (Geometric Mean Titer) were 3.63 (GII.4) and 3.88 (GII.17) respectively, and sustained to the 15th week. The HBGA blocking antibodies were 130 (GII.4) and 360 (GII.17) respectively at the end of the 4th week. Additionally, there was a dramatically statistical difference found in the cross-reactivity within genogroup (GII.3, GII.4 and GII.17) (p < .001), and also showed similar difference between genogroups (GI.1 vs. GII.3, GII.4 and GII.17) (p < .001). Summarized the pPICZa pichi pichia expression system showed a potential to be the alternative for expression of norovirus VLPs in secretion form, and the little cross-reactivity found between the endemic strain and the epidemic strain provides an evident for the consideration of selecting candidates of norovirus vaccine strains.

Chronic kidney disease linked to SARS-CoV-2 infection: a case report.

BACKGROUND: The recent COVID-19 pandemic has raised concerns about patient diagnosis and follow-up of chronically ill patients. Patients suffering from chronic illnesses, concomitantly infected by SARS-CoV-2, globally tend to have a worse prognosis and poor outcomes. Renal tropism and acute kidney injury following SARS-CoV-2 infection has recently been described in the literature, with elevated mortality rates. Furthermore, patients with pre-existing chronic kidney disease, infected by SARS-CoV-2, should be monitored carefully. Here, we report the case of a 69-year-old patient with splenic marginal zone lymphoma, suffering from longstanding chronic kidney disease following SARS-CoV-2 infection. CASE PRESENTATION: A 69-year-old male patient previously diagnosed with pulmonary embolism and splenic marginal zone lymphoma (Splenomegaly, Matutes 2/5, CD5 negative and CD23 positive), was admitted to the hospital with shortness of breath, fever and asthenia. A nasopharyngeal swab test was performed in addition to a CT-scan, which confirmed SARS-CoV-2 infection. Blood creatinine increased following SARS-CoV-2 infection at 130 µmol/l, with usual values at 95 µmol/l. The patient was discharged at home with rest and symptomatic medical treatment (paracetamol and hydration), then readmitted to the hospital in August 2020. A kidney biopsy was therefore conducted as blood creatinine levels were abnormally elevated. Immunodetection performed in a renal biopsy specimen confirmed co-localization of SARS-CoV2 nucleocapsid and protease 3C proteins with ACE2, Lewis x and sialyl-Lewis x antigens in proximal convoluted tubules and podocytes. Co-localization of structural and non-structural viral proteins clearly demonstrated viral replication in proximal convoluted tubules in this chronically ill patient. Additionally, we observed the co-localization of sialyl-Lewis x and ACE2 receptors in the same proximal convoluted tubules. Reverse Transcriptase-Polymerase Chain Reaction test performed on the kidney biopsy was negative, with very low Ct levels (above 40). The patient was finally readmitted to the haematology department for initiation of chemotherapy, including CHOP protocol and Rituximab. CONCLUSIONS: Our case emphasizes on the importance of monitoring kidney function in immunosuppressed patients and patients suffering from cancer following SARS-CoV-2 infection, through histological screening. Further studies will be required to decipher the mechanisms underlying chronic kidney disease and the putative role of sialyl-Lewis x and HBGA during SARS-CoV-2 infection.

Nonsecretor Histo-blood Group Antigen Phenotype Is Associated With Reduced Risk of Clinical Rotavirus Vaccine Failure in Malawian Infants.

BACKGROUND: Histo-blood group antigen (HBGA) Lewis/secretor phenotypes predict genotype-specific susceptibility to rotavirus gastroenteritis (RVGE). We tested the hypothesis that nonsecretor/Lewis-negative phenotype leads to reduced vaccine take and lower clinical protection following vaccination with G1P[8] rotavirus vaccine (RV1) in Malawian infants. METHODS: A cohort study recruited infants receiving RV1 at age 6 and 10 weeks. HBGA phenotype was determined by salivary enzyme-linked immunosorbent assay (ELISA). RV1 vaccine virus shedding was detected by quantitative real-time polymerase chain reaction (qRT-PCR) in stool collected on alternate days for 10 days post-immunization. Plasma rotavirus-specific immunoglobulin A was determined by ELISA pre- and post-immunization. In a case-control study, HBGA phenotype distribution was compared between RV1-vaccinated infants with RVGE and 1:1 age-matched community controls. Rotavirus genotype was determined by RT-PCR. RESULTS: In 202 cohort participants, neither overall vaccine virus fecal shedding nor seroconversion differed by HBGA phenotype. In 238 case-control infants, nonsecretor phenotype was less common in infants with clinical vaccine failure (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.20-0.75). Nonsecretor phenotype was less common in infants with P[8] RVGE (OR, 0.12; 95% CI, 0.03-0.50) and P[4] RVGE (OR, 0.17; 95% CI, 0.04-0.75). Lewis-negative phenotype was more common in infants with P[6] RVGE (OR, 3.2; 95% CI, 1.4-7.2). CONCLUSIONS: Nonsecretor phenotype was associated with reduced risk of rotavirus vaccine failure. There was no significant association between HBGA phenotype and vaccine take. These data refute the hypothesis that high prevalence of nonsecretor/Lewis-negative phenotypes contributes to lower rotavirus vaccine effectiveness in Malawi.

Human Group C Rotavirus VP8*s Recognize Type A Histo-Blood Group Antigens as Ligands.

Group/species C rotaviruses (RVCs) have been identified as important pathogens of acute gastroenteritis (AGE) in children, family-based outbreaks, as well as animal infections. However, little is known regarding their host-specific interaction, infection, and pathogenesis. In this study, we performed serial studies to characterize the function and structural features of a human G4P[2] RVC VP8* that is responsible for the host receptor interaction. Glycan microarrays demonstrated that the human RVC VP8* recognizes type A histo-blood group antigens (HBGAs), which was confirmed by synthetic glycan-/saliva-based binding assays and hemagglutination of red blood cells, establishing a paradigm of RVC VP8*-glycan interactions. Furthermore, the high-resolution crystal structure of the human RVC VP8* was solved, showing a typical galectin-like structure consisting of two ß-sheets but with significant differences from cogent proteins of group A rotaviruses (RVAs). The VP8* in complex with a type A trisaccharide displays a novel ligand binding site that consists of a particular set of amino acid residues of the C-D, G-H, and K-L loops. RVC VP8* interacts with type A HBGAs through a unique mechanism compared with that used by RVAs. Our findings shed light on the host-virus interaction and the coevolution of RVCs and will facilitate the development of specific antivirals and vaccines.IMPORTANCE Group/species C rotaviruses (RVCs), members of Reoviridae family, infect both humans and animals, but our knowledge about the host factors that control host susceptibility and specificity is rudimentary. In this work, we characterized the glycan binding specificity and structural basis of a human RVC that recognizes type A HBGAs. We found that human RVC VP8*, the rotavirus host ligand binding domain that shares only ∼15% homology with the VP8* domains of RVAs, recognizes type A HBGA at an as-yet-unknown glycan binding site through a mechanism distinct from that used by RVAs. Our new advancements provide insights into RVC-cell attachment, the critical step of virus infection, which will in turn help the development of control and prevention strategies against RVs.

Structural basis for norovirus neutralization by an HBGA blocking human IgA antibody.

Human noroviruses (HuNoVs) cause sporadic and epidemic gastroenteritis worldwide. They are classified into two major genogroups (GI and GII), with each genogroup further divided into multiple genotypes. Susceptibility to these viruses is influenced by genetically determined histo-blood group antigen (HBGA) expression. HBGAs function as cell attachment factors by binding to a surface-exposed region in the protruding (P) domain of the capsid protein. Sequence variations in this region that result in differential HBGA binding patterns and antigenicity are suggested to form a basis for strain diversification. Recent studies show that serum antibodies that block HBGA binding correlate with protection against illness. Although genogroup-dependent variation in HBGA binding specificity is structurally well characterized, an understanding of how antibodies block HBGA binding and how genotypic variations affect such blockade is lacking. Our crystallographic studies of the GI.1 P domain in complex with the Fab fragment of a human IgA monoclonal antibody (IgA 5I2) with HBGA blocking activity show that the antibody recognizes a conformational epitope formed by two surface-exposed loop clusters in the P domain. The antibody engulfs the HBGA binding site but does not affect its structural integrity. An unusual feature of the antigen recognition by IgA 5I2 is the predominant involvement of the CDR light chain 1 in contrast to the commonly observed CDR heavy chain 3, providing a unique perspective into antibody diversity in antigen recognition. Identification of the antigenic site in the P domain shows how genotypic variations might allow escape from antibody neutralization and exemplifies the interplay between antigenicity and HBGA specificity in HuNoV evolution.

Seroprevalence of antibodies against GII.4 norovirus among children in Pune, India.

This study reports the seroprevalence of antibodies against GII.4 norovirus among children (≤5 years) in Pune, India. Of 191 serum specimens, 98 (51.3%) tested positive with 61, 34 and 3 having IgG, IgG-IgA and IgG-IgA-IgM, respectively. Histoblood group antigen (HBGA)-blocking antibodies were detected in 33 of the 54 tested positive specimens. IgG and blocking antibody prevalence and titer varied with age and was lowest among children aged 6-23 months. Antibody-positive children, suggesting past norovirus exposure, showed significantly lower faecal norovirus RNA detection rate than antibody-negative children. Further investigation of the seroepidemiology of norovirus infections in India is warranted. J. Med. Virol. 88:1636-1640, 2016. © 2016 Wiley Periodicals, Inc.

Rotavirus P[8] Infections in Persons with Secretor and Nonsecretor Phenotypes, Tunisia.

To determine whether rotavirus infections are linked to secretor status, we studied samples from children in Tunisia with gastroenteritis. We phenotyped saliva for human blood group antigens and tested feces for rotavirus. Rotavirus was detected in 32/114 patients. Secretor genotyping showed that P[8] rotavirus infected secretors and nonsecretors, and infection correlated with presence of Lewis antigen.

Detection of unusual G6 rotavirus strains in Italian children with diarrhoea during the 2011 surveillance season.

Two rare G6 rotavirus A (RVA) strains, designated as RVA/human-wt/ITA/CEC06/2011/G6P[6] and RVA/human-wt/ITA/PG05/2011/G6P[9], were identified in stool specimens from children hospitalized in Central Italy. After PCR genotyping, the samples CEC06 and PG05 gave G-UD-P[6] and G-UD-P[9] genotypes, respectively. To determine the G-type and to characterize further the two strains, sequencing of 8 of the 11 genomic segments was performed. CEC06 and PG05 strains were found to possess unusual genotype constellations: G6-P[6]-I2-A2-N2-T2-E2-H2 and G6-P[9]-I2-A3-N2-T3-E3-H3, respectively. This study reports the first detection of rare G6P[6] and G6P[9] RVA strains in peninsular Italy. Phylogenetic analysis of VP4 (VP8*), VP7, VP6, and NSP1-5 showed no evidence of zoonosis or inter-species reassortment, revealing for both strains constellations previously associated to human cases.

Biological and physico-chemical characterization of human norovirus-like particles under various environmental conditions.

Human noroviruses (HuNoVs) are the predominant etiological agent of viral gastroenteritis in all age groups worldwide. Mutations over the years have affected noroviruses' responses to environmental conditions due to the arrangement of amino acid residues exposed on the VP1 capsid surface of each strain. The GII.4 HuNoV genotype has been the predominant variant for decades, while the GII.17 genotype has often been detected in East Asia since 2014. Here, GII.17 and GII.4 baculovirus-expressed VLPs (virus-like particles) were used to study the biological (binding to HuNoV ligand, namely the ABO and Lewis antigens) and physicochemical properties (size, morphology, and charge) of the HuNoV capsid under different conditions (temperature, pH, and ionic strength). GII.17 showed stability at low and high ionic strength, while GII.4 aggregated at an ionic strength of 10 mM. The nature of the buffers influences the morphology and stability of the VLPs. Here, both VLPs were highly stable from pH 7-8.5 at 25 °C. VLPs retained HBGA binding capability for the pH, ionic strength and temperature encountered in the stomach (fed state) and the small intestine. Increasing the temperature to above 65 °C altered the morphology of VLPs, causing aggregation, and decreased their affinity to HBGAs. Comparing both isolates, GII.17 showed a better stability profile and higher affinity to HBGAs than GII.4, making them interesting candidate particles for a future norovirus vaccine. Biological and physicochemical studies of VLPs are as pertinent as ever in view of the future arrival of VLP-based HuNoV vaccines.

Elucidating the conformational dynamics of histo-blood group antigens and their interactions with the rotavirus spike protein through computational lens.

In the present study, we investigated the conformational dynamics of histo-blood group antigens (HBGAs) and their interactions with the VP8* domain of four rotavirus genotypes (P[4], P[6], P[19], and P[11]) utilizing all-atom molecular dynamics simulations in explicit water. Our study revealed distinct changes in the dynamic behavior of the same glycan due to linkage variations. We observed that LNFPI HBGA having a terminal ß linkage shows two dominant conformations after complexation, whereas only one was obtained for LNFPI with a terminal α linkage. Interestingly, both variants displayed a single dominant structure in the free state. Similarly, LNT and LNnT show a shift in their dihedral linkage profile between their two terminal monosaccharides because of a change in the linkage from ß(1-3) to ß(1-4). The molecular mechanics generalized Born surface area (MM/GBSA) calculations yielded the highest binding affinity for LNFPI(ß)/P[6] (-13.93 kcal/mol) due to the formation of numerous hydrogen bonds between VP8* and HBGAs. LNnT binds more strongly to P[11] (-12.88 kcal/mol) than LNT (-4.41 kcal/mol), suggesting a single change in the glycan linkage might impact its binding profile significantly. We have also identified critical amino acids and monosaccharides (Gal and GlcNAc) that contributed significantly to the protein-ligand binding through the per-residue decomposition of binding free energy. Moreover, we found that the interaction between the same glycan and different protein receptors within the same rotavirus genogroup influenced the micro-level dynamics of the glycan. Overall, our study helps a deeper understanding of the H-type HBGA and rotavirus spike protein interaction.Communicated by Ramaswamy H. Sarma.

Serological surveillance of GI norovirus reveals persistence of blockade antibody in a Jidong community-based prospective cohort, 2014-2018.

Introduction: Herd immunity against norovirus (NoV) is poorly understood in terms of its serological properties and vaccine designs. The precise neutralizing serological features of genotype I (GI) NoV have not been studied. Methods: To expand insights on vaccine design and herd immunity of NoVs, seroprevalence and seroincidence of NoV genotypes GI.2, GI.3, and GI.9 were determined using blockade antibodies based on a 5-year longitudinal serosurveillance among 449 residents in Jidong community. Results: Correlation between human histo-blood group antigens (HBGAs) and GI NoV, and dynamic and persistency of antibodies were also analyzed. Seroprevalence of GI.2, GI.3, and GI.9 NoV were 15.1%-18.0%, 35.0%-38.8%, and 17.6%-22.0%; seroincidences were 10.0, 21.0, and 11.0 per 100.0 person-year from 2014 to 2018, respectively. Blockade antibodies positive to GI.2 and GI.3 NoV were significantly associated with HBGA phenotypes, including blood types A, B (excluding GI.3), and O+; Lewis phenotypes Leb+/Ley+ and Lea+b+/Lex+y+; and secretors. The overall decay rate of anti-GI.2 antibody was -5.9%/year (95% CI: -7.1% to -4.8%/year), which was significantly faster than that of GI.3 [-3.6%/year (95% CI: -4.6% to -2.6%/year)] and GI.9 strains [-4.0%/year (95% CI: -4.7% to -3.3%/year)]. The duration of anti-GI.2, GI.3, and GI.9 NoV antibodies estimated by generalized linear model (GLM) was approximately 2.3, 4.2, and 4.8 years, respectively. Discussion: In conclusion, enhanced community surveillance of GI NoV is needed, and even one-shot vaccine may provide coast-efficient health benefits against GI NoV infection.

Use of a Smartphone-Based Medication Adherence Platform to Improve Outcomes in Uncontrolled Type 2 Diabetes Among Veterans: Prospective Case-Crossover Study.

BACKGROUND: Medication nonadherence is a problem that impacts both the patient and the health system. OBJECTIVE: The objective of this study was to evaluate the impact of a novel smartphone app with patient-response-directed clinical intervention on medication adherence and blood glucose control in noninsulin-dependent patients with type 2 diabetes mellitus (T2DM). METHODS: We enrolled 50 participants with T2DM not on insulin with smartphones from a rural health care center in Northern Nevada for participation in this case-crossover study. Participants underwent a standard of care arm and an intervention arm. Each study arm was 3 months long, for a total of 6 months of follow-up. Participants had a hemoglobin A1c (HbA1c) lab draw at enrollment, 3 months, and 6 months. Participants had monthly "medication adherence scores" (MAS) and "Self-Efficacy for Appropriate Medication Use Scale" (SEAMS) questionnaires completed at baseline and monthly for the duration of the study. Our primary outcomes of interest were the changes in HbA1c between study arms. Secondary outcomes included the evaluation of the difference in the proportion of participants achieving a clinically meaningful reduction in HbA1c and the difference in the number of participants requiring diabetes therapy escalation between study arms. Exploratory outcomes included the analysis of the variation in medication possession ratio (MPR), MAS, and SEAMS during each study arm. RESULTS: A total of 30 participants completed both study arms and were included in the analysis. Dropouts were higher in participants enrolled in the standard of care arm first (9/25, 36% vs 4/25, 16%). Participants had a median HbA1c of 9.1%, had been living with T2DM for 6 years, had a median age of 66 years, and had a median of 8.5 medications. HbA1c reduction was 0.69% in the intervention arm versus 0.35% in the standard of care arm (P=.30). A total of 70% (21/30) of participants achieved a clinically meaningful reduction in HbA1c of 0.5% in the app intervention arm versus 40% (12/30) in the standard of care arm (odds ratio 2.29, 95% CI 0.94-5.6; P=.09). Participants had higher odds of a therapy escalation while in the standard of care arm (18/30, 60% vs 5/30, 16.7%, odds ratio 4.3, 95% CI 1.2-15.2; P=.02). The median MPR prior to enrollment was 109%, 112% during the study's intervention arm, and 102% during the standard of care arm. The median real-time MAS was 93.2%. The change in MAS (1 vs -0.1; P=.02) and SEAMS (1.9 vs -0.2; P<.001) from baseline to month 3 was higher in the intervention arm compared to standard of care. CONCLUSIONS: A novel smartphone app with patient-response-directed provider intervention holds promise in the ability to improve blood glucose control in complex non-insulin-dependent T2DM and is worthy of additional study.

Bovine natural antibody IgM inhibits the binding of human norovirus protruding domain to its HBGA receptors.

Human norovirus (HuNoV) is the primary viral pathogen that causes acute gastroenteritis (AGE) in humans. The protruding (P) domain of HuNoV interacts with cell surface histo-blood group antigens (HBGAs) to initiate infection. Owing to the lack of an effective in vitro culture method and a robust animal model, our understanding of HuNoVs is limited, and as a result, there are no commercial vaccines or antivirals available at present against the virus. In an attempt to develop a preventative measure, we previously identified that bovine colostrum (bCM) contains functional factors that inhibit the binding of HuNoV P domain to its HBGA receptors. In this study, a candidate functional factor in bCM was identified as immunoglobulin M (IgM) using mass spectrometry, followed by database comparison. The natural antibody IgM was further verified to be a functional protein that inhibited HuNoV P protein binding to HBGA receptors through receptor-binding inhibition experiments using bCM, commercial IgM, and fetal bovine serum. Our findings provide a foundation for future development of natural IgM into an antiviral drug, which may help to prevent and/or treat HuNoV infection.

Epidemiological Impact of GII.17 Human Noroviruses Associated With Attachment to Enterocytes.

For the last 30 years, molecular surveys have shown that human norovirus (HuNoV), predominantly the GII.4 genotype, is one of the main causative agents of gastroenteritis. However, epidemiological surveys have revealed the worldwide emergence of GII.17 HuNoVs. Genetic analysis confirmed that GII.17 strains are distributed into three variants (i.e., Kawasaki 308, Kawasaki 323, and CS-E1). Here, virus-like particles (VLPs) were baculovirus-expressed from these variants to study putative interactions with HBGA. Qualitative analysis of the HBGA binding profile of each variant showed that the most recent and predominant GII.17 variant, Kawasaki 308, possesses a larger binding spectrum. The retrospective study of GII.17 strains documented before the emergence of the dominant Kawasaki 308 variant showed that the emergence of a new GII.17 variant could be related to an increased binding capacity toward HBGA. The use of duodenal histological sections confirmed that recognition of enterocytes involved HBGA for the three GII.17 variants. Finally, we observed that the relative affinity of recent GII.17 VLPs for HBGA remains lower than that of the GII.4-2012 variant. These observations suggest a model whereby a combination of virological factors, such as polymerase fidelity and increased affinity for HBGA, and immunological factors was responsible for the incomplete and non-persistent replacement of GII.4 by new GII.17 variants.