Increased sensitivity of the fluorescent treponemal antibody absorption test with biotin/avidin: a comparison with conventional FTA-ABS.

The biotin/avidin system was adapted to the FTA technique for detection of IgG, IgM, and IgA antibodies specific to Treponema pallidum. By using biotin/avidin IgG antibodies could be detected in a serum dilution 15 000 times higher, and IgM 3 000 times higher than was possible with conventional FTA technique. IgA antibodies, however, were not detected with any of the methods.