Background and Aim :
Toxoplasma gondii is a zoonoses protozoan of the Apicomplexa familythat causes Toxoplasmosis in the worldwide. It is estimated that approximately ۳۰-۵۰% of theworld's population is infected with this parasite. This infection not only reduces meat productionby causing abortion in
sheep and goats, but it can be both a source for human infections and areservoir for parasites, therefore; It causes severe economic losses in the
sheep industry. The aimof this study was to evaluate the immunogenicity of the
live attenuated vaccine with differentadjuvants in
sheep as an intermediate host.Methods : ۲۰ two-month-old pregnant Iranian Qashqaeian serum-negative
sheep for Toxoplasmagondii were randomly divided into five groups of four. Group one injected with media and servedas control. Three experimental groups were immunized subcutaneously with ۱ ml of ۲۵ ×۱۰۶ (۲۵million) inactivate tachyzoites formulated with Montanide, Aluminium hydroxide, and Chitosan,respectively. Last group was inoculated with live attenuated tachyzoite with the same dose.Immunization was performed once. After ۲۱ days, blood samples were collected for ELISA testto evaluate the humoral
immune response and gamma interferon measurement to evaluate thecellular immune response.Results : The highest antibody titer was obtained in the group immunized with Montanideadjuvant, which was significantly different from other groups (P <۰.۰۵). However, the highestcellular immunity according to gamma interferon measurements was related to live attenuatedvaccine which was significantly different from other groups, followed by Chitosan or Aluminumhydroxide adjuvant. It should b notice that all immunized groups had a significant difference withthe control group (P <۰.۰۵).Conclusion : According to the successful
immune response in the live attenuated vaccine, theresults of this study showed that this attenuated strain can provide new research in order to achievea promising vaccine against Toxoplasmosis, which is worth further evaluation in variousintermediate and definitive hosts.