Enterotoxigenic Escherichia coli (ETEC) are common causes of infectious
diarrhea among young children of low-and middle-income countries (LMICs) and travelers to these regions. Despite their significant contributions to the morbidity and mortality associated with childhood and traveler's
diarrhea, no licensed
vaccines are available. Current
vaccine strategies may benefit from the inclusion of additional conserved
antigens, which may contribute to broader coverage and enhanced efficacy, given their key roles in facilitating intestinal colonization and effective
enterotoxin delivery. EatA and
EtpA are widely conserved in diverse populations of ETEC, but their immunogenicity has only been studied in controlled human
infection models and a population of children in Bangladesh. Here, we compared serologic responses to EatA,
EtpA and heat-labile toxin in populations from endemic regions including Haitian children and subjects residing in Egypt, Cameroon, and Peru to US children and adults where ETEC
infections are sporadic. We observed elevated
IgG and
IgA responses in individuals from endemic regions to each of the
antigens studied. In a cohort of Haitian children, we observed increased immune responses following exposure to each of the profiled
antigens. These findings reflect the wide distribution of ETEC
infections across multiple endemic regions and support further evaluation of EatA and
EtpA as candidate ETEC
vaccine antigens.