Effect of Vaccination with Irradiated Tachyzoites on Histopathological Changes and DNA Damage in Hepatocytes of Experimental Toxoplasmosis

Current strategies for the control of toxoplasmosis are based on chemotherapy, however successful vaccine has also been demonstrated. The present study aims to assess the effect of the vaccination with radiation-attenuated tachyzoites in challenged mice regarding histopathological alteration and DNA damage of hepatocytes. Sixty mice were equally divided as follow: Group I left as a normal control group II was infected with 2x10 RH virulent tachyzoites (infected control). Groups III and IV were subdivided into two subgroups a and b where subgroups IIIa and IVa were vaccinated with 2.47 mw-min/cm UV and 0.3 KGy gamma radiation – attenuated tachyzoites respectively without challenge (as vaccine control). Subgroups IIIb and IVb were vaccinated with UV and gamma radiationattenuated tachyzoites and challenged after three weeks with 2x10 3 RH virulent tachyzoites. Livers were examined for histopathological changes and DNA comet assay. It was observed that acute infection with Toxoplasma tachyzoites produced toxic effects which lead to severe damage in liver tissues and DNA of hepatocytes. Meanwhile, the protective effect of UV or gamma radiation-attenuated tachyzoites vaccine resulted in the maintenance of normal histopathological characteristics and DNA of hepatocytes and UV irradiation is better in its protective capacity.