Immunoenzymatic test for Q-fever

An immunoenzymatic test using as antigen purified suspensions of Coxiella burnetti coated by methylglyoxal on microtiter plates was developed. Multiple testing of the same sera gave similar results: two dilutions of serum (1:400 and 1:1600) were used in routine tests. Good agreement between the immunoenzymatic and the indirect immunofluorescent antibody tests was obtained for 41 of 50 sera examined. Five sera negative by the immunofluorescent antibody test were positive by the immunoenzymatic test; this result may be due to the higher sensitivity of the latter test. On the other hand, three sera with higher titers by the indirect immunofluorescent antibody test showed a rather feeble positivity by the immunoenzymatic test. This is probably due to the different specificity of the reacting antibodies in the two methods. The indirect immunofluorescent antibody test permits better distinction of the very high titers (greater than 1:5120) than the immunoenzymatic test. The immunoenzymatic test seems to be the method of choice for seroepidemiology surveys of Q-fever; however, its use for clinical serodiagnosis needs further confirmation.