Antigenic contents of Treponema pallidum preparations

In investigations of syphilis various Treponema pallidum antigens are used to study the immune responses of naturally or experimentally infected hosts. In the past these antigen preparations have rarely been examined for their antigenic contents and activity. In the present study, supernatant, sediment, and solubilised preparations of T pallidum Nichols strain (20 X 10(9) organisms/ml) and T phagedenis biotype Reiter were examined by modified counterimmunoelectrophoresis and immunoblotting for their antigenic contents. No T pallidum antigen was seen in the supernatant fraction, which contained cross reacting (Reiter) antigens and rabbit serum proteins. The remaining T pallidum preparations contained T pallidum antigens, cross reacting treponemal (Reiter) antigens, and rabbit serum proteins. These findings suggest that T pallidum preparations should be examined qualitatively and quantitatively before they are used for monitoring immune responses and interpreting data. Technology for these examinations is available.