[Immunological properties of the 30 kDa antigen of toxoplasma gondii]

Partially purified Toxoplasma gondii antigens by immunoaffinity chromatography

Tachyzoite antigens of Toxoplasma gondii (RH) were partially purified by immunoaffinity chromatography. The cultivated Toxoplasma in vivo (mouse) and in vitro (Hep-2 cell) and peritoneal fluid of T. gondii infected mice were collected for antigen analysis. Tachyzoite antigens collected from infected mouse showed positive bands of 76 kDa, 70 kDa, 64 kDa, 53 kDa, 46 kDa, 44 kDa, 41 kDa, 35 kDa, 25 kDa, 18 kDa, and 13 kDa on immunoblot with anti-Toxoplasma rabbit sera, and those from infected Hep-2 cells revealed reactive bands of 70 kDa, 64 kDa, 53 kDa, 35 kDa 28 kDa, and 13-10 kDa. After applying to an IgG-Sepharose column, two elution peaks, E-1 and E-2 fractions, were obtained from both soluble antigen of T. gondii and the peritoneal fluid of infected mice, respectively. Immunoblots of soluble antigen with immunized rabbit sera revealed positive bands of 97 kDa, 63 kDa, 53 kDa, and 35 kDa from E-1 fraction and 53 kDa and 35 kDa from E-2. In the case of the eluted peaks from mice peritoneal fluid, E-1 showed protein bands of 84 kDa, 76 kDa, 53 kDa, and 29 kDa bands and 53 kDa and 45 kDa from E-2 on immunoblots. Serum IgG antibody titer of mice immunized with T. gondii tachyzoites was increased on 1 week after booster immunization when analysed by ELISA using crude antigen, while it was elevated on 3 weeks after booster immunization by ELISA using purified antigen.