[Expression of S.sonnei form I antigen gene and V.cholerae toxin B subunit gene in S.flexneri 2a strain and investigation of their immunoprotective response in mice].

The genes encoding S. sonnei form I O antigen and V. cholerae B subunit were cloned into an expression vector containing asd gene of Streptococcus mutans by gene recombination. The final recombination plasmid was transformed into the asd mutant of S. flexneri 2a (strain T32). Analysis of LPS silver staining and western blotting indicated that the genes encoding CT-B and form I O antigen could stably express in the asd mutant T32 strain. Immune protection tests in mice showed that the recombinant strain constructed in this study could provide 100% protection against the challenge from S. flexneri 2a and S. Sonnei and also showed a good immune protection (70%) against V. cholerae. This recombinant strain has the following advantages: trivalent, stable and no vector drug resistance markers.