Abstract: | SYNOPSIS. Antisera were developed in rabbits against 3 axenic lines of Trichomonas gallinae: JB(VI), the 6th isolate of the very virulent Jones' Barn strain, which was kept frozen in liquid nitrogen and had its full pathogenicity for pigeons when it was employed for immunization; JB(VI)C, a substrain derived from JB(VI), but attenuated during continuous in vitro cultivation for 1 year; and JB(V)C, a substrain of the 5th isolate of the Jones' Barn strain attenuated during continuous in vitro cultivation for over 3 years. All antisera were reacted on gel diffusion slides with varying concentrations of homologous and heterologous antigens. Two groups of precipitin bands, arbitrarily labeled A and B, were seen on the slides. Analysis of these bands revealed the common genetic makeup of the 3 trichomonad lines with respect to the group A bands. However, the group B antigenic system was strong in the attenuated JB(VI)C and JB(V)C substrains, and very weak in the fully pathogenic JB(VI) strain. These differences are discussed in the light of their possible relationship to pathogenicity. |