A novel tp0548 Gene Type of Treponema pallidum identified in Nanjing, China: Case Report and Review of Literature.

BACKGROUND The tp0548 gene, hypothesized to encode for an outer membrane protein(OMP), was originally used in the ECDCT for molecular typing of T. pallidum. It plays an important role in the molecular epidemiology of Treponema, because it is not only an important locus of multiple typing approaches, but also suitable for strain-typing of multiple Treponema subspecies. METHODS A 27-year-old Chinese man attended the Institute of Dermatology, Chinese Academy of Medical Sciences Sexually Transmitted Disease (STD) Clinic in Nanjing, China due to a genital ulcer and inguinal lymphadenopathy for one week. Work-up consisted of microbiological and haematological investigations, and sequences analysis. The aim of this study was to describe a novel tp0548 sequence-type "Qn" of this syphilis strain and to review all previously reported novel tp0548 genotypes. RESULTS we identified a novel tp0548 gene type in a genital ulcer in a primary syphilis patient in Nanjing, China. Using sequence alignment, we further found that this novel sequence was closely similar to "Q". Following the nomenclature used in the enhanced CDC-typing methodology, the letters "Qn" was assigned to the new sequence-type. CONCLUSION The novel tp0548 sequence-type of T. pallidum not only expands the database up to 27 different sequence types but also indicates the substantial genetic diversity of the tp0548 gene sequence.