Intestinal shedding of enteric agents in histo-blood group antigen-secretor children in an Australian community-based birth cohort study

Histo-blood group antigens are inherited polymorphic glycans expressed on mucosal epithelial cell surfaces and shed in secretions. They act as receptors for gastrointestinal pathogens. Those expressing these antigens are categorized as secretors and have an increased susceptibility to gastrointestinal infections, particularly from some norovirus and rotavirus genotypes. However, high-level evidence of association between secretor status and susceptibility is lacking for many other gastrointestinal pathogens. We compared differences in detection rates for 8 viruses, 5 bacteria, and 4 protozoa in children under 2 years of age enrolled in the Australian Observational Research in Childhood Infectious Diseases birth cohort study. Their secretor status was determined by phenotyping (ABO, Lewis, UEA-I) and genotyping test results. Data from polymerase chain reaction assay testing of weekly stool samples collected from birth as well as daily symptom and illness diaries were analyzed. Incidence rates were calculated by secretor status and compared using incidence rate ratios for each pathogen. Additional comparisons included symptomatic/asymptomatic detections, illness severity, and healthcare utilization by secretor status. Eighty-four children (77% secretors) participated for an exposure period of 157 child-years. The incidence rates of norovirus GI, GII, wild-type rotavirus, and Campylobacter detections were more than 50% higher in secretors than non-secretors, but lower for Blastocystis. For these pathogens, secretor status was not associated with symptomatic illness, severity, or healthcare use. Our results confirmed the previously known higher susceptibility to norovirus GII infections in secretors but displayed variations in susceptibility to other pathogens. This study strengthens the evidence for norovirus susceptibility in Australian children.