تغيير ويرولانس توكسوپلاسما گونديي

VIRULENCE MODIFICATION OF TOXOPLASMA GONDII

The study of T . gondii virulence is an important aspect in parasitology. A virulent T. gondii were isolated from sheep and rooster brains using mice bioassay. After intraperitoneal inoculation of tissue cysts, tachyzoites were harvested from the peritoneal cavity. Forty-six serial passages of tachyzoites were used exudates with the exception of 23 to 26 th passages. Number of harvested tachyzoites and survival times of mice were compared in 1th, 5th, 12th, 22th and 46th passages. The number of tachyzoites and survival time were also compared with RH strain . Virulence of T. gondii was increased after serial passages of avirulent tachyzoites in the mice . Initially , tachyzoites were non-lethal for the mice, although after serial passages they began to kill the mice . Interestingly at this stage, even inoculation of 500 tachyzoites were iethal for the mice . In comparision with RH stain, the number of harvested tachyzoites were significantly decreased , but survival time of the mice were slightly increased .