How Does Syphilis Avoid Immune Detection?

Treponema pallidum is the bacteria that causes the STD Syphilis. And while Syphilis is well-known, there is no vaccine for it and reinfection is possible. Why is this?

New Research by the University of Washington reveals that Treponema pallidum avoids immune detection by modifying a surface protein, Tprk. The researchers took blood samples stored from one patient who was infected multiple times. They sequenced the full length of the Tprk genes from both samples and found that it didn't match.

"Using deep profiling of the full-length Tprk gene, we found surprisingly that the two isolates did not share any full-length Tprk sequences"

Treponema pallidum mutates the Tprk gene frequently in order to prevent the immune system from detecting it. A new infection will have a very different Tprk surface protein making the immunity built against it less effective.

Surface proteins are essential for our immune system to target and destroy invading bacteria. This new research should help to guide research in developing a vaccine.

Source: doi:10.1371/journal.pntd.0007921