biostudies-literatureJackson-Litteken CDNational Institute of Allergy and Infectious DiseasesNIAID NIH HHSNational Institute of General Medical SciencesOffice of the Vice Chancellor for Research and InnovationNIGMS NIH HHSArkansas Biosciences Institutee0012348https://www.ebi.ac.uk/biostudies/studies/S-EPMC11293673biostudies-literatureUnknown18(7)Relapsing fever (RF), a vector-borne disease caused by Borrelia spp., is characterized by recurring febrile episodes due to repeated bouts of bacteremia. RF spirochetes can be geographically and phylogenetically divided into two distinct groups; Old World RF Borrelia (found in Africa, Asia, and Europe) and New World RF Borrelia (found in the Americas). While RF is a rarely reported disease in the Americas, RF is prevalent in endemic parts of Africa. Despite phylogenetic differences between Old World and New World RF Borrelia and higher incidence of disease associated with Old World RF spirochete infection, genetic manipulation has only been described in New World RF bacteria. Herein, we report the generation of genetic tools for use in the Old World RF spirochete, Borrelia duttonii. We desPLoS neglected tropical diseasesDevelopment and validation of systems for genetic manipulation of the Old World tick-borne relapsing fever spirochete, Borrelia duttonii.PMC11293673R03 AI151432P20 GM103625P20GM103625P30 GM145393R03AI151432P30GM145393Voth DEHogland BAMcFadden LJackson-Litteken CDBlevins JSGuo WRatliff CTFullerton MSRego ROMfalseDevelopment and validation of systems for genetic manipulation of the Old World tick-borne relapsing fever spirochete, Borrelia duttonii.Relapsing fever (RF), a vector-borne disease caused by Borrelia spp., is characterized by recurring febrile episodes due to repeated bouts of bacteremia. RF spirochetes can be geographically and phylogenetically divided into two distinct groups; Old World RF Borrelia (found in Africa, Asia, and Europe) and New World RF Borrelia (found in the Americas). While RF is a rarely reported disease in the Americas, RF is prevalent in endemic parts of Africa. Despite phylogenetic differences between Old World and New World RF Borrelia and higher incidence of disease associated with Old World RF spirochete infection, genetic manipulation has only been described in New World RF bacteria. Herein, we report the generation of genetic tools for use in the Old World RF spirochete, Borrelia duttonii. We des2024-01-01T00:00:00Z2024 Jul2026-05-02T12:42:31.638Z2025-02-19T02:27:26.648ZS-EPMC112936733903804710.1371/journal.pntd.0012348