ABSTRACT
Clinical and laboratory investigations were carried out as part of a program to develop vaccines that can stimulate anti-adhesion (anti-pilus) immunity to protect man against diarrhea due to enterotoxigenic Escherichia coli (ETEC). A parenteral vaccine consisting of purified type 1 somatic pili from H10407 was evaluated for safety, immunogenicity and efficacy. Enterotoxigenic Escherichia coli are an important cause of travelers' diarrhea, infant diarrhea in less-developed countries, and enteric colibacillosis of piglets, calves, and lambs. Most strains of E. coli that cause diarrhea in these young animals possess accessory virulence properties in addition to heat-labile (LT) and/or heat-stable (ST) enterotoxins. Intestinal SlgA anti-pili antibody was measured before and after immunization in the final immunogenicity/efficacy study. Human intestinal fluids were standardized to a concentration of 20 mg% SlgA then serially diluted twofold and tested by ELISA for SlgA antibody to type 1 somatic pili, CFA/I, CFA/II, enterotoxin, or O antigen.
