Immunoglobulin M and G antibodies in mice in response to Toxoplasma gondii (S-273) infection and their antigen recognition patterns in western blotting on various post-infection days.

Immunoglobulin M and G antibody responses in mice experimentally infected with Toxoplasma gondii (S-273) and the reaction patterns with T. gondii (RH) tachyzoite antigens were studied on various post-infection days (PIDs) (2nd to 36th PIDs) using a commercially available IgM and IgG enzyme linked immunosorbent assay (ELISA) test systems and Western blotting (WB) technique. IgM antibody in ELISA test appeared to be positive on 12th PID (absorbance 0.764) and reached its peak level on 16th PID (absorbance 1.338) showing a slow decline thereafter with an absorbance of 0.800 even on 36th PID. Positivity of IgM was confirmed by WB except for 36th PID. IgG appeared on 16th PID with an absorbance of 0.248 and showed a steady increasing tendency even on 36th PID (absorbance 1.747). However, IgG positivity on WB was observed only on 29th PID and afterwards. On Western blots, both IgM and IgG showed interesting antigen recognition patterns on various PIDs. At the most IgM recognised seven antigens of 14kDa to 53kDa while IgG recognised eight antigens of 17kDa to 53kDa. Major antigens recognised by IgM were of 53kDa and 21kDa while the major band recognised by IgG was of 19kDa. The major bands, however, showed variability in their consistency during various PIDs. All the antigens recognised by IgM and IgG were not identical.