Live non-invasive Shigella dysenteriae 1 strain induces homologous protective immunity in a guinea pig colitis model

摘要

A non-invasive live transconjugant Shigella hybrid (LTSH Delta stx) strain was constructed from a Shiga toxin gene deleted mutant of Shigella dysenteriae 1 by introducing a plasmid vector pPR1347 that carried a lipopolysaccharide biosynthesis gene (rfb and rfc) of Salmonella typhimurium. In guinea pigs, four successive oral administrations of LTSH Delta stx showed complete protection against rectal challenge with wild type S. dysenteriae 1 strain. Exponential increase of the serum IgG and IgA titer against lipopolysaccharide of LTSH Delta stx was observed during immunization, peaked on day 28 and remained at that level until day 35 after the initiation of the immunization. In intestinal lavage of the immunized animals, significant increase of IgA titer against lipopolysaccharide of LTSH Delta stx was also observed. These data suggested that LTSH Delta stx could be a useful candidate to induce protective immunity against S. dysenteriae 1 infection.