Syphilis Tp is a spirochaeta bacterium that causes the venereal disease syphilis. Although the incidence of syphilis in the United States was declining after the outbreak, the incidence of syphilis in Europe was increasing from 1986 to 1991. In 1992, especially in the countries of the Russian Federation, the country peaked with 263 cases. The World Health Organization reported 12 million new cases in 1995. At present, the positive rate of syphilis serological testing in HIV-infected individuals has been increasing recently.

Syphilis antibody combination rapid detection is a side-flow chromatography immunoassay.
The test kit consists of: 1) a purple-red conjugated mat colloidal gold (Tp conjugate) bound to a rabbit recombinant Tp antigen IgG gold conjugate.

2) Nitrocellulose film strip band containing test band (T) and control band (C band). The T-band is pre-coated with non-conjugated recombinant Tp antigen, and the C-band is pre-coated with goat anti-rabbit IgG antibody.

When a sufficient volume of the sample is allocated to the sample hole, in the carton, the sample is migrated on the carton by capillary action. If anti-TP antibodies are present in the specimen, they will bind to the Tp conjugate. This immune complex is then trapped on the membrane by the pre-coated Tp antigen, forming a purple-red T-band that indicates a positive test result for the Tp antibody. Absence of T-band indicates negative results. Tests containing internal controls (C band) should show immune complexes of purple-red band goat anti-rabbit IgG/ Rabbit IgG gold conjugate, regardless of its T-band. Otherwise, the test results are invalid and another device must be used.