摘要:In a virulent strain of Vibrio cholerae, KB9, P and V plasmids were introduced by bacterial conjugation. Characterization of PV isolates and systematic screening of them in animal models of cholera revealed that a large number of PV isolates were non-pathogenic, owing to the loss of ability to synthesize toxin. Results obtained with two such strains, designated as KB9:PV and CD24, are described. The strains with plasmids were stable during in vitro cultivation or during two successive passages in rabbit intestine. Protection conferred by PV strains was determined in mouse protection tests and in the rabbit ileal loop model. The plasmid strains were immunogenic. In view of the results, it is proposed that PV-bearing attenuated strains should be tried in oral immunization. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (673K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 643 644 645 646 647