Purification of Chlamydia psittaci antigen by affinity chromatography on polymyxin B agarose for use in the enzyme-linked immunosorbent assay (ELISA).

The purification of cell wall antigens of Chlamydia psittaci by affinity chromatography on polymyxin B agarose is described. Chlamydial cell wall antigens were prepared using different methods: heat treatment, ultrasonication and sodium deoxycholate treatment. The antigens were subsequently purified by gel chromatography. The highest amount of cell wall antigens was obtained by heat treatment of the chlamydiae at 90 degrees C and pH 8.5. The purified antigens showed molecular weights of 450 kDa to 700 kDa. Treatment of heat-extracted antigens with trypsin, pronase E or proteinase K did not destroy antigenic activity or alter the molecular weight. On the other hand, potassium metaperiodate treatment led to a significant decrease of both. Chlamydial cell wall antigens extracted by heat treatment and purified by affinity chromatography were used as ELISA-antigen. Using this ELISA and the complement fixation test (CFT), a total of 576 bovine sera was tested. 92 of these sera reacted positively in the ELISA and only 13 in the CFT. In addition, the prepared ELISA was compared with a commercial ELISA. 12 out of 15 sera tested were positive when using the ELISA described and 10 were positive when using the commercial ELISA.