RESUMO
Using toxin-coregulated adhesion pili (TCP), the etiologic agent of cholera is able to colonize human small intestine, where this pathogen proceeds with the production of the secreted cholera toxin (CT), inducing the development of severe diarrhea. At the same time, TCP and CT are not only the major factors of pathogenicity but also form a part of the group of key protective antigens. Immunoenzyme, immunoblotting, self-agglutination investigations, electron-microscopic studies, and electrophoretic assay of the outer membrane proteins showed that the recombinant plasmid carrying a number of cloned genes of two prophages, CTX and RS1, introduced into model Vibrio cholerae strains classical biovariant, resulted in the formation of strains with an enhanced rate of synthesis of three protective antigens: CT, TCP, and an outer membrane protein, OmpU. A simultaneous increase in the level of biosynthesis of the three antigens in V. cholerae was demonstrated to be specified by alterations in the expression of the toxR regulatory gene. Information was obtained suggesting that the transcriptional activity of toxR gene was dependent on the activity of rstC antirepressor gene derived from RS1 pro-phage and localized in the cloned fragment. Strains hyperproducing the three protective antigens can be used to construct more efficient non-living cholera vaccines, and to isolate the indicated proteins applicable to the development of diagnostic test-systems.
