Specific anti-Toxoplasma antibodies in relation to infection and reinfection using different infective stages
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The possibility of rat re-infection with different Toxoplasma gondii stages was studied in this work. Two groups of rats were infected with either intra-peritoneal injection of 1000 trophozoites of virulent Toxoplasma strain or 1000 oocysts .through oral routes. IgA, IgM and 1gG were detected 15, 30, 60 and 120 days post infections. IgA and 1gM appeared as early as 15 days post infection but declined after wards. IgA antibody response was more prominent with oocyst infection and IgM was more prominent with tachyzoites infection with insignificant statistical difference. On the other hand, IgG started to increase. 60 days post infection, then increased gradually till the end of the experiment (120 days). The primary orally infected rats were either re-infected orally with oocysts or intra-peritoneal trophozoites and re-examined after 15 and 120 days for the same immunological parameters. Those rats which primary infected with intra-peritoneal trophozoites were re-examined after oral infection with oocysts or injection of trophozoites intraperitoneal. The level of IgA and IgM in one rat of group A and 2 rats of group B are significantly increased and this occurred in presence of anti-Toxoplasma IgG from the primary infection. In this study, the rats were lab-bred so, the factors affect the immune system could be under control, also strain variability It 1•11,10.11411.11.1114•• • was excluded as the infection was by only one strain, and as the IgG level was high, these rats were presumed to be immune from the primary infection. So the rats which became positive after challenge most probably re-infected.