| Title |
Immunological Responses Induced by asd and wzy/asd Mutant Strains of Salmonella enterica serovar Typhimurium in BALB/c Mice |
| Author |
Hong Hua Piao1,2, Vo Thi Minh Tam1,2, Hee Sam Na3, Hyun Ju Kim1,2, Phil Youl Ryu1, Soo Young Kim1,2, Joon Haeng Rhee1,2, Hyon E. Choy1,2, Suhng Wook Kim4, and Yeongjin Hong1,2* |
| Address |
1Clinical Vaccine R&D Center, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea, 2Department of Microbiology, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea, 3Department of Microbiology, Dankook University College of Medicine, Cheonan 330-714, Republic of Korea, 4Department of Clinical Laboratory Science, College of Health Science, Korea University, Seoul 135-703, Republic of Korea |
| Bibliography |
Journal of Microbiology, 48(4),486-495, 2010,
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| DOI |
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| Key Words |
Salmonella enterica serovar Typhimurium, live vaccine, immune responses, wzy and asd |
| Abstract |
Attenuated bacteria have long been developed as vaccine candidates but can have some disadvantages, such as the potential for damage to immune organs due to insufficient clearance. To minimize these disadvantages, we generated Salmonella enterica serovar Typhimurium mutants SHJ2104 (asd::cm) and HTSaYA (wzy::km, asd::cm). The wzy gene codes for the O-antigen polymerase, which is involved in lipopolysaccharide (LPS) biosynthesis, and asd codes for aspartate ß- semialdehyde dehydrogenase, which participates in cell wall formation. The strains synthesized LPS with a short-chain length, and showed lower cytotoxicity and reduced intracellular proliferation in animal cells compared to wild-type bacteria. After oral infection, the mutants were cleared in immune tissues, including the Peyer’s patch, mesenteric lymph node, and spleen, within 5 days. The LD50 of the mutants in Balb/c mice was estimated to be 106 higher than wild-type bacteria when administered either via an oral or i.p. route, indicating that the two strains are highly attenuated. To compare the immune response to and protective effects of the mutants against wild-type bacterial infection, we inoculated the mutants into mice via an oral (1×1010 CFU) or i.p. (1×107 CFU) route once or twice at a two week interval. All immune responses, such as serum IgG and secretory IgA levels, cytokine production, and delayed hypersensitivity, were highly induced by two rounds of immunization. HTSaYA and SHJ2104 induced similar immune responses, and mice immunized with HTSaYA or SHJ2104 via an i.p. route were protected against wild-type Salmonella infection even at 100-fold of the LD50 (5×106 CFU). Taken together, these data indicate that HTSaYA and SHJ2104 could be developed as live attenuated Salmonella vaccine candidates. |
