Exposure to Human and Bovine Noroviruses in a Birth Cohort in Southern India from 2002 to 2006

Abstract

cHuman and bovine norovirus virus-like particles were used to evaluate antibodies in Indian children at ages 6 and 36 months and their mothers. Antibodies to genogroup II viruses were acquired early and were more prevalent than antibodies to genogroup I. Low levels of IgG antibodies against bovine noroviruses indicate possible zoonotic transmission. N oroviruses (NoVs) are nonenveloped, single-stranded positive-sense RNA viruses, accounting for ϳ50% of gastroenteritis outbreaks worldwide (1). Seroepidemiological surveys using NoV virus-like particles (VLPs) as antigens show exposure to NoVs across the globe (2-7), with high seroprevalence in children Ͻ5 years of age; seroprevalence can reach 100% in adults (2,8,9). Analyses of bovine strains suggest close relation to human NoV genogroup I (GI) and . Studies from the Netherlands found that 22% of the population had antibodies to bovine NoV, with veterinarians having high frequencies of antibodies (15), raising the possibility of zoonotic transmission (16). In this study, sera from children in a birth cohort and their mothers were used to assess exposure to human and bovine norovirus genogroups in early life and adulthood.The study population was a birth cohort from semiurban slums in Vellore, South India, recruited and monitored from 2002 to 2006, with sample collection as previously described (17)(18)(19). Maternal sera at delivery and sera from children at 6 and 36 months were tested for IgG antibodies against human and bovine viruses. Diarrheal samples from calves were collected from a veterinary clinic and a commercial dairy farm in 2007 and 2008 (20). Written informed consent was obtained from parents of all children; the study was approved by the Institutional Review Board of the Christian Medical College, Vellore, India.The NoV GIII and NB VLPs were obtained from Linda Saif, Ohio State University (21). Validation assays were carried out prior to use of bovine VLPs using 20 bovine sera from a veterinary clinic. Goat anti-bovine IgG-horseradish peroxidase (IgG-HRP; (Jackson ImmunoResearch Inc., United States) was added, followed by addition of 3,3=,5,5=-tetramethylbenzidine substrate solution. The reaction was stopped with 2 M sulfuric acid after 15 min, and optical density (OD) was measured at 450 nm.Serum IgG was detected using plates coated overnight with 2 g/ml of human and bovine VLPs in phosphate-buffered saline (PBS) at 4°C, and the plates were blocked using 10% skim milk in PBS. Diluted serum samples were added to uncoated and VLPcoated wells and incubated. Anti-human IgG (Southern Biotech, United States) was added, followed by goat anti-mouse IgG-HRP (human adsorbed; Southern Biotech) and the substrate 2,2=-azino-di(3-ethylbenzthiazoline-6-sulfonate) solution; the reaction was stopped using 1% SDS solution, and OD was measured at 405 nm.The assays for human and bovine VLPs differed in the standards and controls included on each plate. The GI and GII standard curves were 2-fold dilutions of positive human sera starting at a 1:100 dilution, and the GI...

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

“…Globally, the GII.4 antibody (IgG) seroprevalence in this age‐group has been reported to vary between 56.1% and 92.3% [Pelosi et al, ; Nicollier‐Jamot et al, ; Nurminen et al, ; Carmona‐Vicente et al, ; Liu et al, ]. Seroprevalence in southern India has been reported elsewhere recently (Menon et al, ,), however, the data were not comparable due to differences in study population (age), method of antibody detection, and VLPs employed in the assays.…”

Epidemiology of human noroviruses and updates on vaccine development

“…1a) [5,6]. Seroepidemiology studies detect antibodies to GIII bovine NoVs in human populations; however, this may be because of cross reactive epitopes between bovine and human NoVs as bovine NoVs bind to a glycan not present in human tissues [7,8]. …”

Animals as Reservoir for Human Norovirus

“…This regular detection of novel strains and the reporting of human-like norovirus genotypes in stool samples of symptomatic and asymptomatic farm animals have sparked interest in the possible role of animals as potential zoonotic reservoir for these emerging strains [9,10,11,12]. Antibodies directed against bovine and canine norovirus have been detected in humans suggesting some level of exposure of humans to animal norovirus [13,14,15,16]. For other viruses of the Caliciviridae family, interspecies transmission has been reported including some case reports of zoonotic events between marine mammals and humans (reviewed in [17]).…”