Treponema pallidum is not culturable in standard laboratory media. The serological diagnosis of syphilis uses two types of antibodies. The antigen used in the non-treponemal tests (VDRL/RPR) is:
- A T. pallidum specific outer membrane proteins (OmpA)
- B Cardiolipin-lecithin-cholesterol complex (lipid antigen released from host damaged cells) ✓
- C T. pallidum inner membrane lipoprotein TpN47
- D Flagellar core protein FlaB of T. pallidum
Explanation
VDRL and RPR (non-treponemal tests) use cardiolipin-lecithin-cholesterol (a mitochondrial membrane-derived antigen released from damaged host cells during T. pallidum infection) as the test antigen; antibodies against this lipid antigen (reagin) are produced in syphilis but also in other conditions causing tissue damage (false positives in SLE, pregnancy, malaria, leprosy, viral infections). Treponemal tests (TPHA, FTA-ABS, TPPA) use T. pallidum-specific antigens. TpN47 is a specific treponemal antigen. FlaB is a treponemal flagellar protein used in specific treponemal assays.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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