SIMULTANEOUS EXPRESSION OF CFA/I AND CS3 COLONIZATION FACTOR ANTIGENS OF ENTEROTOXIGENIC ESCHERICHIA-COLI BY DELTA-AROC, DELTA-AROD SALMONELLA-TYPHI VACCINE STRAIN CVD-908

Among the known colonization factors of enterotoxigenic Escherichia coli (ETEC), CFA/I and CS3 (the common antigen in the CFA/II family of fimbrial antigens) are two of the most prevalent fimbrial antigens found in clinical isolates but are never expressed by the same wild-type strain. We manipulated the genetic determinants encoding CS3 and CFA/I fimbriae so that these two important colonization factors are expressed simultaneously in attenuated Salmonella typhi live oral vaccine strain CVD 908, including after growth in liquid medium (CFA/I is poorly expressed by wild-type ETEC in broth culture), The recombinant fimbrial structures produced by CVD 908 ave morphologically indistinguishable from the CS3 fibrillae and CFA/I rod-like fimbriae produced by ETEC, and are recognized by monospecific CS3 and CFA/I antibodies, This prototype construct may prove useful in investigating the live vector approach to immunoprophylaxis of ETEC diarrheal disease.