Molecular epidemiology of Treponema pallidum in a Frontier region of the Russian Federation (Tuva Republic)

Abstract

This article reports the results of typing 111 T. pallidum subsp. pallidum samples from Tuva Republic in 2013–2016. Samples were evaluated in molecular assays using variable genes arp, tpr (E, G, J), and tp0548 for the typing of Treponema pallidum strains. Seven molecular subtypes of the syphilis causative agent were identified over the whole period. The predominant type was 14 d/f (90.1%), followed by 14 b/f (1.8%), 14 c/f (1.8%), 14 d/g (0.9%) and 14 i/f (0.9%). Molecular subtypes 4 d/f and 9 d/f (0.9% each) identified in 2015, were previously described in Shanghai and northeastern China. In the period of 2015–2016 three cases of simultaneous presence of 2 arp types (9 and 14) in the clinical samples were identified for the first time. The comparison of the typing results with the current data of the syphilis molecular epidemiology allowed to conclude the similiarity of the T. pallidum subsp. population of the Tuva Republic with the Russian population in whole and its diversity from the populations described in the P. R. China and Western Europe.