Immuno-electron microscopic localization of antigenic sites for specific immunoglobulins G and M on Toxoplasma gondii surface.

The results of immuno-electron microscopic reaction obtained with anti-IgG and/or anti-IgM ferritin conjugated sera after the inter-reaction of RH strain with specific IgG and/or IgM immunosera, confirm: 1) antigenic sites for specific immunoglobulins both IgG and IgM localization on superficial membrane of pellicular complex; 2) the saturation of common antigenic surface sites due to the competition between IgG and IgM; 3) the competitive prevalence of IgG even if IgM concentration is relatively high in unfractioned immunosera. The practical application of such results is discussed in relation to the specific tests for IgM evidentiation during primary response.