Evaluation of Razi attenuated variety of Toxoplasma gondii in Balb/c mice

Currently, the live vaccine Toxovax is produced from the attenuated variety of Toxoplasma (T.) gondii. The aim of this study was to evaluate the immunogenicity of live variety of T. gondii which was produced through serial passages in cell culture in Shiraz, Razi Institute. Twenty-four Balb/C mice were randomly divided into three groups. Group I was the negative control and received cell culture media. Group II as positive control and group III were inoculated with acute and Razi strains of T. gondii, respectively. All mice were assessed daily and potential mortality was recorded. Twenty-eight days later blood sample were collected from all groups for ELISA and then all mice were challenged with injections of acute strain of T. gondii. The results showed that in the control group, mortality started from day 8 and up to14 days after challenge, all mice of this group died. Similar to the first group, mortality was started in the positive control group 8 days after challenge and all mice died until the day 18. The interesting finding was that the mortality rate was 50% in the third group. These results suggest that the Razi variety of T. gondii caused partial immunity in mice and this variety doesn’t cause disease and mortality in mice.