Fluorescent antibody inhibition test for Coccidioides immitis antibodies.

Abstract

The results of a study to develop a fluorescent antibody (FA) inhibition test for the demonstration of antibodies to Coccidioides immitis are presented. Endospores formed in vivo were used as antigen in this test; the conjugate used had been prepared from antiglobulins of rabbits infected with C. immitis. Ninety-one sera from confirmed human cases of coccidioidomycosis and 15 sera from individuals affected with other diseases were tested by FA inhibition, and the results compared with those obtained by the complement fixation (CF) procedure. These sera were tube precipitin (TP) negative. Of these 106 sera, 80 were positive by both the FA and CF tests, and 14 were negative by both, for an overall agreement of approximately 88%. Eleven additional sera that were TP positive but CF negative were positive by the FA technique. The findings indicate that the FA inhibition technique can be used for the rapid detection of antibodies to C. immitis in sera.