Treponema pallidum is the bacterium that causes lues or syphilis. The infection that causes treponema pallidum is divided into four stages called primary, secondary, latent and tertiary syphilis, these stages depend on the duration of the infection and the immune status of the host. During the primary and secondary stages, there are often no or mild symptoms. After that, symptoms such as fever, muscle aches, headache, sore throat, eye inflammation and an ulcer on or around the genitals may develop. Without treatment, the disease can progress to the tertiary stages and inflammation can develop in various organs. Treponema pallidum invades the skin or mucosa through microlesions, or through blood products or organ transplantation.

Diagnosis of primary syphilis consists of PCR diagnosis of a biopsy of the lesion. Diagnosis for the other forms of syphilis also consists of a PCR diagnosis, in which specific antibodies of treponema pallidum are detected. The antibodies are only detectable in the latent phase. The sample used for diagnosis is a swab of genital ulcer or urine. The sequence detected is the polA gene, this gene encodes DNA polymerase 1. This gene contains 4 unique insertions of 20 to 30 amino acids each that are not seen in other DNA polymerase l enzymes. Due to these features, the polA gene is amplified during PCR diagnosis. The polA gene also has an essential role in the initiation of DNA replication.