Demonstration of Group- and Species-Specific Antigens of Chlamydial Agents by Gel Diffusion

Abstract

Recently, agents belonging to the genus Chlamydia were recognized as being divided into 2 species: Chlamydia trachomatis and Chlamydia psittaci [1]. A study of the antigens of chlamydial agents by the agar gel diffusion method was undertaken in an attempt to demonstrate antigenic differences between species of this genus. In a previous report [2] it was shown that treatment of purified particle suspensions of C. psittaci strains, meningopneumonitis, feline pneumonitis, psittacosis, and C. trachomatis, strain TE-55, with sodium deoxycholate extracted Chlamydia group antigen. The group character of this antigen was shown in agar diffusion by the comparison of extracts from strains of both species and the observation that the lines of precipitation that formed with rabbit immune serum fused in reaction of identity. Chlamydia particles, after deoxycholate extraction, were treated further by sonication. The resulting sonicate formed 2 lines of precipitation with homologous antiserum. One line, which was formed near the serum well, was shown to be group-specific. Evidence for species specificity of the second line, which was formed near the antigen well, was obtained when the sonicate of TE55 was compared with sonicates of strains of C. psittaci. Further characterization of deoxycholate extract and sonicate antigens is reported here.