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

Abstract

A non-invasive live transconjugant Shigella hybrid (LTSH 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 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 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 stx was also observed. These data suggested that LTSH stx could be a useful candidate to induce protective immunity against S. dysenteriae 1 infection.

Protective immunity by oral immunization with heat‐killed Shigella strains in a guinea pig colitis model

“…Rectal challenge was carried out as described previously with some modifications . After four successive oral immunizations, the guinea pigs in the immunized and control groups were challenged on Day 28 with cells of a virulent Shigella strain.…”

“…The invasiveness of these strains was confirmed by the Sereny test . A Shiga toxin gene‐deleted mutant of S. dysenteriae 1 (NT4907Δ stx ) was constructed as described previously .…”

“…Oral immunization of guinea pigs with 1 mL of the heat‐killed cell suspensions of the Shigella strains was carried out on Days 0, 7, 14, and 21, as described previously . Briefly, the animals were fasted for 36 hr but given water ad libitum .…”

Host Receptor Immunomodulation in Response to <i>Shigella</i> Surface Antigens: An Insight for Vaccine Development

“…Earlier many Shigella spp. and their surface components have been identified and used as mucosal vaccine candidates (Barman et al, 2011;Iankov et al, 2004;Kaminski and Oaks, 2009;Kuehn and Kesty, 2005;Mitra et al, 2012;Pore et al, 2009) but their immune-stimulatory effects were less defined. Lack of immuno-stimulatory features of the target candidates often does not elicit strong mucosal immunity (Borisova, 1999).…”

“…However, studies on T-cell subsets suggest a biased induction of Th2 (Azim et al, 1996;Islam et al, 1995b). Therefore, lack of protective Th1 response during most of the experimental studies suggests a nature of T-cell suppression (Barman et al, 2011). Present scenario demands an alternative approach to our existing concept on cell-mediated immunity in shigellosis.…”