Identification of positively selected genes in human pathogenic treponemes: Syphilis-, yaws-, and bejel-causing strains differ in sets of genes showing adaptive evolution

Abstract

In the genus Treponema there are several human and animal pathogens that include the causative agent of syphilis (Treponema pallidum ssp. pallidum; TPA), the causative agent of yaws (T. p. ssp. pertenue; TPE), and the causative agent of endemic syphilis (T. p. ssp. endemicum; TEN). T. paraluisleporidarum causes venereal spirochetosis in rabbits. We used whole genome sequences of 11 treponemal strains together with additional 62 draft genomic data to identify genes evolving under positive selection. The identified genes evolving under positive selection partly overlapped with the genes previously reported as recombinant and were found to be different in treponemal subspecies. Since both genetic recombination and positive selection could allow a survival of pathogenic bacteria despite the human immune response, identification of such genes could predict the major antigens recognized by the human immune system and also identify the most suitable components for development of an anti-treponemal vaccine.In the genus Treponema there are several human and animal pathogens that include the causative agent of syphilis (Treponema pallidum ssp. pallidum; TPA), the causative agent of yaws (T. p. ssp. pertenue; TPE), and the causative agent of endemic syphilis (T. p. ssp. endemicum; TEN). T. paraluisleporidarum causes venereal spirochetosis in rabbits. We used whole genome sequences of 11 treponemal strains together with additional 62 draft genomic data to identify genes evolving under positive selection. The identified genes evolving under positive selection partly overlapped with the genes previously reported as recombinant and were found to be different in treponemal subspecies. Since both genetic recombination and positive selection could allow a survival of pathogenic bacteria despite the human immune response, identification of such genes could predict the major antigens recognized by the human immune system and also identify the most suitable components for development of an anti-treponemal vaccine.