ABSTRACT
Objective:To establish a new molecular typing method for Treponema pallidum (TP) based on TP0136 protein sequence heterogeneity. Methods:The amino acid sequences of TP0136 open reading frame (ORF) of 9 strains of Treponema pallidum ssp. Pallidum (TPA) , 3 strains of Treponema pallidum ssp. Pertenue (TPE) , 1 unclassified simian strain of Treponema Fribourg-Blanc (FB) and 1 strain of Treponema pallidum ssp. Endemicum (TEN) were searched from Genbank, and multiple sequence comparisons were performed to obtain the molecular typing results of TP0136 protein. The TP0136 protein-based molecular typing method was used to classify 23 TPA clinical isolates, which were collected from Dermatology Hospital of Southern Medical University from January 2015 to December 2018, and the typing results were compared with those by the traditional typing method based on the tp0548/Arp/Tpr genes. Results:TP0136 protein was highly heterogeneous in different TP strains. According to the amino acid sequence of TP0136, TPE, FB and TEN strains were divided into 4 subtypes of Ⅰ- Ⅳ, TPA strains were divided into 6 subtypes of Ⅴ-Ⅹ, and TPA clinical strains were classified into 4 subtypes of Ⅶ, Ⅸ, Ⅹ, Ⅺ. Through the traditional typing method described above, 23 TPA clinical strains could be divided into 5 types (13D/d, 14D/f, 14D/g, 15D/f, 16A/e) . By using the TP0136 protein-based typing method combined with traditional typing method, the above clinical strains could be further subdivided into 10 types, and the 14D/f type could be further divided into 3 subtypes by using the TP0136 protein-based typing method.Conclusion:The TP0136 protein-based molecular typing method can be used to distinguish TP species, which is helpful for further improvement of traditional TPA molecular typing.