Human Treponema pallidum 11q/j isolate belongs to subsp. endemicum but contains two loci with a sequence in TP0548 and TP0488 similar to subsp. pertenue and subsp. pallidum,respectively

Background: treponema pallidum subsp. endemicum (ten) is the causative agent of endemic syphilis (bejel). an unusual human ten 11q/j isolate was obtained from a syphilis-like primary genital lesion from a patient that returned to france from pakistan. methodology/principal findings: the ten 11q/j isolate was characterized using nested pcr followed by sanger sequencing and/or direct illumina sequencing. altogether,44 chromosomal regions were analyzed. overall,the 11q/j isolate clustered with ten strains bosnia a and iraq b as expected from previous ten classification of the 11q/j isolate. however,the 11q/j sequence in a 505 bp-long region at the tp0488 locus was similar to treponema pallidum subsp. pallidum (tpa) strains,but not to ten bosnia a and iraq b sequences,suggesting a recombination event at this locus. similarly,the 11q/j sequence in a 613 bp-long region at the tp0548 locus was similar to treponema pallidum subsp. pertenue (tpe) strains,but not to ten sequences. conclusions/significance: a detailed analysis of two recombinant loci found in the 11q/j clinical isolate revealed that the recombination event occurred just once,in the tp0488,with the donor sequence originating from a tpa strain. since ten bosnia a and iraq b were found to contain tpa-like sequences at the tp0548 locus,the recombination at tp0548 took place in a treponeme that was an ancestor to both ten bosnia a and iraq b. the sequence of 11q/j isolate in tp0548 represents an ancestral ten sequence that is similar to yaws-causing treponemes. in addition to the importance of the 11q/j isolate for reconstruction of the ten phylogeny,this case emphasizes the possible role of ten strains in development of syphilis-like lesions. © 2017 mikalová et al.