Common Cytoplasmic Antigen in Five Acholeplasma Species

Abstract

Two-dimensional immunoelectrophoresis was used to study the antigenic composition and serological relationships of the following five Acholeplasma species: Acholeplasma axanthtim, Acholeplasma equifetale, Acholeplasma granulation, Acholeplasma hippikon, and Acholeplasma laidlawii. A total of 15 to 25 precipitin peaks were observed in the homologous reactions. A. equifetale and A. hippikon were most closely related serologically, having six related antigens. Nearly all antigens were negatively charged at pH 8.6; the only exceptions were one antigen of A. axanthum and one antigen of A. laidlawii. The “positively charged” antigens were membrane associated and did not cross-react. One common antigen was recognized in each organism by all heterologous antisera. Monospecific antiserum prepared against the common antigen (peak 0.72 of A. hippikon) reacted with one antigen in each species tested. The electrophoretic mobilities of the common antigen ranged from 0.45 (A. axanthum) to 0.72 (A. hippikon). This antigen was located in the cytoplasm of A. laidlawii because the antiserum reacted only with the cytoplasmic fractions, not with the membrane fractions. The recognition of a common cytoplasmic antigen in the Acholeplasmataceae is important to the taxonomy of these organisms.