Borrelia carolinensissp. nov., a New (14th) Member of theBorrelia burgdorferiSensu Lato Complex from the Southeastern Region of the United States

Approximately 118Borrelia isolates were cultured from a variety of rodents, birds, and ticks collected in the southern United States. In addition to a highly diverse group ofBorrelia bissettii strains and a homogenous group ofBorrelia burgdorferi sensu stricto strains, a group of 16 isolates with unusual characteristics was found. The isolates were cultured from ear biopsy samples of the rodentsPeromyscus gossypinus andNeotoma floridana trapped at five localities in South Carolina. A multilocus sequence analysis of therrf -rrl intergenic spacer, 16S rRNA,fla ,ospA , andp66 genes were used to clarify the taxonomic status of the new group ofB. burgdorferi sensu lato isolates. Thirteen species of theB. burgdorferi sensu lato complex were used as controls. Unique restriction fragment length polymorphism patterns of therrf -rrl intergenic spacer region andfla gene were recognized. Unique signature nucleotides were also found in the 16S rRNA gene. A phylogenetic analysis shows that the 16 new isolates cluster together but separately from the other species in theB. burgdorferi sensu lato complex. Our data strongly support the recognition of the 16 isolates as a newB. burgdorferi sensu lato species. We propose to name this genospecies “Borrelia carolinensis ” with respect to the place of its currently known geographic location.