Detection of Antibody to Chlamydia psittaci: Comparison of Antibody Titers in Human Sera Assayed by Enzyme-linked Immunosorbent Assay (ELISA) and Microplate Immunofluorescence Antibody Technique (MFA)
Antibodies to Chlamydia psittaci in sera of healthy human adults, immunized and nonimmunized animals, rabbits and mice, were assayed by the enzyme-linked immunosorbent assay (ELISA) and then the titers were compared with those assayed by the microplate immunofluorescence antibody technique (MFA). The titers of rabbit and mouse sera determined by these two different methods were virtually identical to each other in both specificity and sensitivity. However, many of the human sera showed nonspecific, false positive reaction in the ELISA test. The results indicated that the MFA was more reliable than the ELISA and that the titers obtained by the ELISA had to be examined by other titration method to confirm the specificity. Such disadvantage was not seen in the MFA for the titration of antichlamydial human sera.