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Forum on Immunopathological Diseases and Therapeutics
SJR: 0.309 SNIP: 0.041 CiteScore™: 0.18

ISSN Druckformat: 2151-8017
ISSN Online: 2151-8025

Archives: Volume 1, 2010 to Volume 7, 2016

Forum on Immunopathological Diseases and Therapeutics

DOI: 10.1615/ForumImmunDisTher.2017020184
pages 181-190

Why Are There Two Genetically Distinct Syphilis-Causing Strains?

David Šmajs
Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic
Lenka Mikalova
Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic
Michal Strouhal
Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic
Linda Grillova
Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, Building A6, 625 00 Brno, Czech Republic

ABSTRAKT

Genetic analyses of Treponema pallidum subsp. pallidum (TPA) reference strains and human clinical isolates have revealed that there are two genetically distinct groups of TPA strains, one group related to the reference strain TPA Nichols (Nichols-like strains) and the second to the TPA SS14 strain (SS14-like strains). In general, the diversification of syphilis-causing strains into SS14- and Nichols-like groups is consistent with geographical and population separation of syphilis-infected human societies, such as separation of American and European populations before the 15th century, and this isolation could explain the missing intermediates between the two groups of TPA strains. In addition, whereas SS14-like strains are predominant among contemporary worldwide clinical isolates, a predominance of Nichols-like strains among reference laboratory strains (isolated in the United States during the 1900s) was found. The possible reasons for these discrepancies are discussed, but the ultimate reasons of both the diversification of syphilis-causing strains into SS14- and Nichols-like groups as well as the contemporary worldwide predominance of SS14-like strains in the human population remain unknown.