Syphilis is a disease caused by Spirochete bacterium called Treponema pallidum (TP). If untreated, the organisms move throughout the body and can cause damage to many organs, making syphilis a life-threatening disease if not treated early enough.

Screening for syphilis in risk population is important for restriction and prevention of the spread of the disease.

Serological tests for Treponema pallidum include two categories. Non-treponemal tests directing at the lipid antigen, such as VDRL and RPR, treponemal-specific tests such as TPHA and FTA-ABS. The former suffers from lack of specificity and sensitivity generating false positive and false negative results, while to the latter, the lack of reactive antigen can lead to poor presentations of the test.

The progresses in molecular biology, genetics and immunology allowed the developments of enzyme-linked assays which utilize recombinant proteins for detection of TP antibodies. These tests are aiming at different TP antibodies and their use has become a routine in the clinical laboratory practice and blood donor screening. They have also helped to establish alternative methods in replacing the present TP serological diagnostic and screening test