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Protective Capacity of L‐Form Salmonella typhimurium against Murine Typhoid in C3H/HeJ Mice
Author(s) -
Nishikawa Fumiko,
Kita Eiji,
Yamada Hideki,
Nakano Akira,
Kashiba Shuzo
Publication year - 1994
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.1348-0421.1994.tb01754.x
Subject(s) - salmonella , biology , microbiology and biotechnology , immunization , spleen , immunity , vaccination , typhoid fever , population , antigen , salmonella enterica , antibody , salmonella typhi , virology , immune system , immunology , bacteria , escherichia coli , medicine , biochemistry , genetics , environmental health , gene
L forms of Salmonella typhimurium LT2 conferred strong protection to a lethal challenge with its parental bacterium on innately hypersusceptible C3H/HeJ mice, and its minimal protective dose was approximately 150 L‐forming units. Although L‐form S. typhimurium was avirulent for C3H/HeJ mice, it multiplied slowly in both the liver and spleen with the maximal growth 2–3 weeks after immunization and thereafter it persisted in the liver until 24 weeks. Protective immunity began to work between 4 and 6 weeks after immunization, and it remained active as long as the L forms colonized the liver (until 24 weeks after immunization). Vaccination with the L form induced a population of T cells responding to L‐form whole‐cell lysate (WCL), while delayed‐type hypersensitivity (DTH) to the extract of S. typhimurium was induced after the establishment of solid immunity. Moreover, neither T‐cell responses nor DTH to heat‐killed S. typhimurium was generated. In addition, antibody responses were elicited to WCL but not to heat‐killed S. typhimurium. These results indicate that protection conferred by the L forms is attributable to the persistent colonization of the L forms rather than the presence of DTH, and also that Salmonella cytoplasmic antigens are involved in induction of immunological responses by vaccination with the L forms.