Method Description

Syphilis IgG

Microtitration wells, coated with whole-cell sonicated Treponema pallidum (Nichols strain) antigens are incubated with serum specimens, which may contain specific antibodies to T pallidum. After incubation, unbound components in the test sample are washed away. IgG antibodies from the specimen that bound to T pallidum antigens are detected using monoclonal anti-human IgG secondary antibodies conjugated to horseradish peroxidase during a second incubation period. Following a second wash cycle, the enzyme conjugate on bound secondary antibodies is detected following addition of TMB (tetramethylbenzidine). The enzymatic reaction is stopped using 1 N sulfuric acid. The assay is measured spectrophotometrically to indicate the presence or absence of IgG treponemal antibodies relative to a cut-off calibrator.(Package insert: CAPTIA Syphilis (T pallidum )-G. Trinity Biotech; 800-970-29 Rev H, 10/2013)

Rapid Plasma Reagin Screen and Titer:

The rapid plasma reagin titer test is a macroscopic screening assay done with unheated serum. Reagin reacts with nontreponemal antigen containing colloidal charcoal particles. This reaction results in a visual flocculation of the black particles against the white card background. The test yields a positive or negative result, and all positive samples are titered to determine the highest positive dilution.(Huber TW, Storms S, Young P, et al. Reactivity of microhemagglutination, fluorescent treponemal antibody absorption, Venereal Disease Research Laboratory, and rapid plasma reagin tests in primary syphilis. J Clin Microbiol. 1983;17[3]:405-409; Kaur G, Kaur P. Syphilis testing in blood donors: an update. Blood Transfus. 2015;13[2]:197-204)

Syphilis Antibody, Treponema pallidum- Particle Agglutination

The Serodia Treponema pallidum particle agglutination (TP-PA) test is based on the agglutination of colored gelatin particle carriers sensitized with T pallidum (Nichols Strain) antigen. Serum samples are serially diluted in microplate wells. Sensitized gelatin particles are added to respective wells and the contents of the plate mixed. The mixture is incubated for 2 hours at ambient temperature. Serum containing specific antibodies will react with the antigen-sensitized colored gelatin particles to form a smooth mat of agglutinated particles in the microplate well. A compact button formed by the settling of the non-agglutinated particles characterizes negative reactions. The agglutination patterns are read visually to determine interpretation.(Package insert: Serodia TP-PA. Fujirebio Diagnostics, Inc.; 05/2024)