Relationship Between Rotavirus P[6] Infection in Korean Neonates and Histo-Blood Group Antigen: a Single-Center Study

Vaccine Take of RV3-BB Rotavirus Vaccine Observed in Indonesian Infants Regardless of HBGA Status

BACKGROUND

Histo-blood group antigen (HBGA) status may affect vaccine efficacy due to rotavirus strains binding to HBGAs in a P genotype-dependent manner. This study aimed to determine if HBGA status affected vaccine take of the G3P[6] neonatal vaccine RV3-BB.

METHODS

DNA was extracted from stool samples collected in a subset (n = 164) of the RV3-BB phase IIb trial in Indonesian infants. FUT2 and FUT3 genes were amplified and sequenced, with any single-nucleotide polymorphisms analyzed to infer Lewis and secretor status. Measures of positive cumulative vaccine take were defined as serum immune response (immunoglobulin A or serum-neutralizing antibody) and/or stool excretion of RV3-BB virus. Participants were stratified by HBGA status and measures of vaccine take.

RESULTS

In 147 of 164 participants, Lewis and secretor phenotype were determined. Positive vaccine take was recorded for 144 (97.9%) of 147 participants with the combined phenotype determined. Cumulative vaccine take was not significantly associated with secretor status (relative risk, 1.00 [95% CI, .94-1.06]; P = .97) or Lewis phenotype (relative risk, 1.03 [95% CI, .94-1.14]; P = .33), nor was a difference observed when analyzed by each component of vaccine take.

CONCLUSIONS

The RV3-BB vaccine produced positive cumulative vaccine take, irrespective of HBGA status in Indonesian infants.

Culture of Human Rotaviruses in Relevant Models Shows Differences in Culture-Adapted and Nonculture-Adapted Strains

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.

Genotypic shift in rotavirus associated with neonatal outbreaks in Seoul, Korea

BACKGROUND

Rotavirus group A (RVA) is a causative agent of acute gastroenteritis among young children worldwide, despite the global expansion of rotavirus vaccination. In Korea, although the prevalence of RVA has been reduced among young children owing to vaccination, nosocomial infections still occur among neonates.

OBJECTIVES

The aim of this study was to investigate the molecular epidemiology of RVA strains associated with several neonatal outbreaks in Seoul from 2017 to 2020.

STUDY DESIGN

Clinical and environmental samples were collected and screened for the presence of RVA using ELISA and PCR targeting VP6, respectively. RVA-positive strains were genotyped via RT-PCR and subsequent sequencing of VP4 and VP7 and were phylogenetically compared with RVA strains from other countries.

RESULTS

During 2017-2020, a total of 15 RVA outbreaks occurred at neonatal facilities (six in hospital neonatal wards and nine in postpartum care centers) in Seoul, and only two RVA genotypes were detected: G4P[6] and G8P[6]. G8P[6] emerged in Seoul November 2018 and immediately became the predominant genotype among neonates, at least up to 2020. Phylogenetic analysis revealed that the G8P[6] genotype in this study was closely related to G8P[6] strains first identified in Korea in 2017, but differed from G8P[6] strains detected in Africa.

CONCLUSIONS

A novel G8P[6] genotype of RVA strains has emerged and caused outbreaks among neonates in Seoul. Continued surveillance for circulating RVA genotypes is imperative to monitor genotype changes and their potential risks to public health.

The Association between Symptomatic Rotavirus Infection and Histo-Blood Group Antigens in Young Children with Diarrhea in Pretoria, South Africa

OBJECTIVES

Recently, histo-blood group antigens (HBGAs) have been identified as receptors or attachment factors of several viral pathogens. Among rotaviruses, HBGAs interact with the outer viral protein, VP4, which has been identified as a potential susceptibility factor, although the findings are inconsistent throughout populations due to HBGA polymorphisms. We investigated the association between HBGA phenotypes and rotavirus infection in children with acute gastroenteritis in northern Pretoria, South Africa.

METHODS

Paired diarrheal stool and saliva samples were collected from children aged ≤ 59 months (n = 342) with acute moderate to severe diarrhea, attending two health care facilities. Rotaviruses in the stool samples were detected by commercial EIA and the rotavirus strains were characterized by RT-PCR targeting the outer capsid VP7 (G-type) and VP4 (P-type) antigens for genotyping. Saliva-based ELISAs were performed to determine A, B, H, and Lewis antigens for blood group typing.

RESULTS

Blood type O was the most common blood group (62.5%) in this population, followed by groups A (26.0%), B (9.3%), and AB (2.2%). The H1-based secretors were common (82.7%) compared to the non-secretors (17.3%), and the Lewis antigen positive phenotypes (Le^(a+b+)) were predominant (54.5%). Blood type A children were more likely to be infected by rotavirus (38.8%) than any other blood types. P[4] rotaviruses (21/49; 42.9%) infected only secretor individuals, whereas P[6] rotaviruses (3/49; 6.1%) only infected Le^(a-b-), although the numbers were very low. On the contrary, P[8] rotaviruses infected children with a wide range of blood group phenotypes, including Le^(a-b-) and non-secretors.

CONCLUSIONS

Our findings demonstrated that Lewis antigens, or the lack thereof, may serve as susceptibility factors to rotaviral infection by specific VP4 genotypes as observed elsewhere. Potentially, the P[8] strains remain the predominant human VP4 genotype due to their ability to bind to a variety of HBGA phenotypes.

The Role of Host Glycobiology and Gut Microbiota in Rotavirus and Norovirus Infection, an Update

Rotavirus (RV) and norovirus (NoV) are the leading causes of acute gastroenteritis (AGE) worldwide. Several studies have demonstrated that histo-blood group antigens (HBGAs) have a role in NoV and RV infections since their presence on the gut epithelial surfaces is essential for the susceptibility to many NoV and RV genotypes. Polymorphisms in genes that code for enzymes required for HBGAs synthesis lead to secretor or non-secretor and Lewis positive or Lewis negative individuals. While secretor individuals appear to be more susceptible to RV infections, regarding NoVs infections, there are too many discrepancies that prevent the ability to draw conclusions. A second factor that influences enteric viral infections is the gut microbiota of the host. In vitro and animal studies have determined that the gut microbiota limits, but in some cases enhances enteric viral infection. The ways that microbiota can enhance NoV or RV infection include virion stabilization and promotion of virus attachment to host cells, whereas experiments with microbiota-depleted and germ-free animals point to immunoregulation as the mechanism by which the microbiota restrict infection. Human trials with live, attenuated RV vaccines and analysis of the microbiota in responder and non-responder individuals also allowed the identification of bacterial taxa linked to vaccine efficacy. As more information is gained on the complex relationships that are established between the host (glycobiology and immune system), the gut microbiota and intestinal viruses, new avenues will open for the development of novel anti-NoV and anti-RV therapies.

Serological Humoral Immunity Following Natural Infection of Children with High Burden Gastrointestinal Viruses

Acute gastroenteritis (AGE) is a major cause of morbidity and mortality worldwide, resulting in an estimated 440,571 deaths of children under age 5 annually. Rotavirus, norovirus, and sapovirus are leading causes of childhood AGE. A successful rotavirus vaccine has reduced rotavirus hospitalizations by more than 50%. Using rotavirus as a guide, elucidating the determinants, breath, and duration of serological antibody immunity to AGE viruses, as well as host genetic factors that define susceptibility is essential for informing development of future vaccines and improving current vaccine candidates. Here, we summarize the current knowledge of disease burden and serological antibody immunity following natural infection to inform further vaccine development for these three high-burden viruses.