Secretory immunoglobulin A (sIgA) in saliva versus virulence proteins of enteropathogenic Escherichia coli (EPEC) in ill and colonized children

Abstract Introduction We evaluated the presence of sIgA in saliva, versus Escherichia coli secreted proteins (Esp) related to the type III secretion system (T3SS), and its semi-quantitative concentration in children under 2 years-old (no longer breastfed) who were previously colonized or infected with enteropathogenic E. coli (EPEC). Methods We analyzed the presence of sIgA in 40 children, who previously had positive cultures for EPEC associated (n = 17) or not associated (n = 23) with diarrhea, using the Western Blot technique versus E. coli secreted proteins: EspABCD. A semi-quantitative measurement of the reaction for each protein was made by its density peaks (OD). Results We found sIgA versus all or some EspABCD proteins in both groups. However, the ill patients had higher concentrations of these antibodies than colonized patients. Discussion The presence of sIgA in saliva could reflect an intestinal immune response and their levels could be related to a greater exposure and/or bacterial load.