ارزیابی پاسخهای ایمنی همورال در مدل موشی پس از تزریق سالمونلا تیفی موریوم ایزوله وحشی ایرانی

Title

Evaluation of Humoral Responses in Mice Model After Injection the Iranian Wild Isolate of Salmonella Thyphimurium

English Abstract

Background & Objectives: Salmonella thyphi which is the causative agent of thyphoid fever, is a human specific pathogen, so it cannot be studied easily due to the lack of animal model. On the other hand Salmonella thyphimurium, which results in an acute self limited gasteroenterit in human and warm blooded animals, causes systemic thyphoid like infection in mice. Here we used Salmonella Thyphimurium in Balb/C mice to evaluate homural responses. Methods: We used Salmonellae thyphimurium RTCC 1679 (control) and RTCC 1735 (Iranian native isolate for test). After determination of LD50, we injected about 27×10 7 CFU/ml formalin-heat killed bacterium to 8 groups of 6-8 weeks old female Balb/c mice via IP (Intra Peritoneal ) or SC (Sub Cutaneous ) routs. Complete Ferund’s adjuvant was used for the first injection and incomplete Ferund’s adjuvant was used in boosters. Injections were done on days : 0,10 and 21 via IP rout , and on days : 0,14 and 28 via SC rout. Blood collecting from orbital sinus on days: 0, 7 ,16, 21,28,35 of injected mice was done and serum samples were used for ELISA technique to measure the concentration of specific IgG anti body. Between the days 28 to 35 live S. thyphimurium was injected for study of vaccine protectivity assay (challenge). After the day 28 we challenged 50% of vaccinated mice with .6 fold of LD50 of live S. Thyphimurium standard and native isolates. Results: Lethal Dose 50 of these bacteria was 36 CFU/ml. Salmonella thyphimurium RTCC 1735 as an Iranian native isolate, not only increased the titer of specific IgG antibody and humoral immunity , but also decreased the mortality of vaccinated mice after challenge, in comparison with RTCC 1679. Conclusion: These results could be considered as a preliminary result for the future study of national Salmonella vaccine.

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