| Summary: | 碩士 === 國立嘉義大學 === 微生物與免疫學系研究所 === 97 === ABSTRACT
Background: Salmonella enterica subspesice enterica Enteritidis (S. Enteritidis) is a broad spectrum host pathogen and infects people through contaminated poultry egg, meat and their products to cause salmonellosis, such as acute gastroenteritis, even bacteremia by evading the host immune system. Therefore, we characterized the pathogenicity of S. Enteritidis in murine and swine.
Materials and methods: The LD50 of 13 clinical S. Enteritidis and laboratory isolates in BALB/c female mice was determined. These S. Enteritidis isolates were separated into two groups. One was clinical isolates collected from blood and stool of patients who visited Chang-Gung memorial hospital. The other was the laboratory strains without or with virulence plasmid or mutagenic virulence plasmid. In the next experiments, we vaccinated the swine with three vaccine strains including S. Typhimurium OU5048 and S. Choleraesuis strains OU7266 and SC2284 respectively at week 0 (W0) and then challenged these swines at W2 with S. Choleraesuis CN36. Blood PMNs and PBMC were collected and then superoxide level of these cells was examined by NBT assay.
Results and discussion: In the mouse experiment, although there was no statistically difference between these two groups, the LD50 was lower in the isolates collected from blood than those isolated from stool. Further analysis demonstrated that virulence plasmid and the pefB, spvB and spvC genes on the virulence plasmid of S. Enteritidis may play some role in enhancing the pathogenicity of S. Enteritidis to mice. In swine experiment, PMNs and PBMC cells of control groups expressed the highest superoxide in W3 and superoxide production differed among weeks in other groups. After interaction with S. Enteritidis, superoxide production of PMNs and PBMC cells was similar between two S. Choleraesuis treated groups, as well as between control and S. Typhimurium groups. However, PMNs and PBMC cells of S. Choleraesuis vaccinated groups expressed more superoxide than control and S. Typhimurium groups. These results suggest that superoxide production of immune-response is specific interaction between host and Salmonella serovar.
Conclusion:
1. The LD50 was lower in the isolates collected from blood than those isolated from stool and the virulence plasmid, especially spvB and spvC on the virulence plasmid, of S. Enteritidis may play important role in pathogenicity to mice.
2. Swines may need 12 weeks to fulfill the maximal superoxide level of PMNs and PBMC.
3. The basal superoxide level was differed pigs among vaccinated pig groups.
4. The S. Enteritidis inhibited superoxide level of PMNs and PBMC.
5. After treating with S. Enteritidis, the PMNs and PBMC of S. Choleaeresuis vaccinated groups produced more superoxide than those of other groups.
6. Superoxide level of PMNs and PBMC differed between virulence and in virulent S. Enteritidis.
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