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Evaluation of the Lon‐Deficient Salmonella Strain as an Oral Vaccine Candidate
Author(s) -
Kodama Chie,
Eguchi Masahiro,
Sekiya Yukie,
Yamamoto Tomoko,
Kikuchi Yuji,
Matsui Hidenori
Publication year - 2005
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2005.tb03700.x
Subject(s) - cecum , microbiology and biotechnology , virulence , biology , spleen , salmonella , mesenteric lymph nodes , immunization , salmonella enterica , serotype , immunogenicity , immune system , immunity , virology , lipopolysaccharide , immunology , bacteria , ecology , biochemistry , genetics , gene
We evaluated the efficacy of CS2022 (the Lon protease‐deficient mutant strain of Salmonella enterica serovar Typhimurium) as a candidate live oral vaccine strain against subsequent oral challenge with a virulent strain administered to BALB/c and C57BL/6 mice. CS2022 persistently resided in the spleen, mesenteric lymph nodes, Peyer's patches, and cecum of both strains of mice after a single oral inoculation with 1 × 10 8 colony‐forming units. Finally, CS2022 almost disappeared from each tissue sample by week 12 in BALB/c mice, whereas CS2022 still resided in each tissue type at week 12 after inoculation of C57BL/6 mice. A significant increase in the serovar Typhimurium lipopolysaccharide‐specific secretory immunoglobulin A (s‐IgA), as measured for one of the mucosal immune responses, was detected in bile and intestinal samples of both strains of immunized mice at week 4 after immunization. In addition, the expression of gamma interferon mRNA in the spleens of both strains of immunized mice, especially those of C57BL/6 mice, was significantly increased at week 4 after immunization and was boosted during the following 5 days after the challenge was administered to the mice. Furthermore, peritoneal macrophages isolated from immunized mice at week 4 after immunization exhibited an increase in intracellular killing activity against both virulent and avirulent Salmonella . The present results suggested that salmonellae‐specific s‐IgA on the mucosal surfaces induced by immunization with CS2022 generally prevented mice from succumbing to an oral challenge with a virulent strain. Simultaneously, CS2022 promoted the protective immunity associated with macrophages in both strains of mice.