Chromosomal integration and expression of the Escherichia coli K88 gene cluster in Salmonella enterica ser. Choleraesuis strain 54 (SC54)

Attempts to develop live vaccines to protect against enterotoxigenic Escher ichia coli (ETEC) infection by induction of both cell-mediated and mucosal immunity, and serum antibody responses have included use of recombinant Sal monella strains that produce K88 fimbrial antigens (Hone et al., 1988; Attr idge et al., 1988 Morona. et al., 1994). However, none of the recombinant S almonella vectors has been licensed by the United States Department of Agri culture (USDA) for use as a live vaccine in pigs in the United States. A va riant of Salmonclla enterica ser. Choleraesuis strain 54 (SC54) is currentl y used as a safe and effective intranasal attenuated live vaccine in pigs. In order to expand the efficacy of this live vaccine strain, we sought to m odify strain SC54 to express the K88 antigens of ETEC. To accomplish this, a plasmid-based system was used to integrate the K88 gene cluster into the chromosome of strain SC54 by site-specific recombination. The K88 antigens were expressed by strain SC54, and the gene cluster was stably maintained i n the host. (C) 2001 Elsevier Science B.V. All rights reserved.