Immunoelectrophoresis was carried out with eleven amebic antigens and three antiamebic sera in order to determine the antigenic moiety of these strains and to describe the antigenic relationships between the various strains. Antigens were prepared from amebae grown in MS-F medium, washed in saline, concentrated and lyophilized. Nitrogen determinations were carried out and each antigen was titered to determine the optimum concentration for immunoelectrophoretic (IEP) analysis. Antisera were prepared in rabbits. Results indicate that strains JS and Laredo have similar IEP patterns, as do strains NRS and 200, Huff and Entamoeba invadens, K9 and JH, and F22 and BH.
Considering the mobilities of the proteins and the similarities of the antigen-antibody arcs, the strains of amebae with similar IEP patterns have several factors in common. The pathogenic strains showed similarities not shared by the non-pathogens and E. invadens. E. invadens was more closely related to Huff which also shares a cultural characteristic, namely growth at room temperature. The strains isolated from extraintestinal infection were similar and those isolated from cases of amebic colitis show similar patterns. Immunoelectrophoretic analysis of these amebic strains demonstrate that immunologic differences do occur.