Phylogenetic Differentiation of Rickettsia parkeri Reveals Broad Dispersal and Distinct Clustering within North American Strains
ORCID
Allerdice: https://orcid.org/0000-0003-2758-3245; Hecht: https://orcid.org/0000-0002-2786-0057; Goddard: https://orcid.org/0000-0002-2617-7141; Karpathy: https://orcid.org/0000-0001-7175-3622
MSU Affiliation
College of Agriculture and Life Sciences; Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology
Creation Date
2026-07-30
Abstract
The tick-borne pathogen Rickettsia parkeri causes a mild rickettsiosis, with cases reported from several countries to its known distribution in the Americas. Molecular analyses have identified a clear distinction between strains of R. parkeri sensu stricto (s. s.) and R. parkeri sensu lato (s. l.) as well as separation between North American and South American R. parkeri s. s. strains. To expand on this previous work, we developed a multilocus sequence typing analysis with two aims: First, to investigate the genetic diversity within strains of North American R. parkeri s. s., and second, to further the understanding of the genetic relationships between R. parkeri s. s. and R. parkeri s. l. Sixty-four R. parkeri isolates and 12 R. parkeri-positive tick lysates were analyzed using a novel typing scheme consisting of four coding regions and two intergenic regions. A concatenated Bayesian phylogeny that identified eight clades was constructed: Three represent the R. parkeri s. l. strains, and five represent the R. parkeri s. s. strains. The clades appear to be generally phylogeographically organized and associated with specific tick vectors. However, while one of the four R. parkeri s. s. North American clades appears to be limited to the southwestern United States, the other North American clades exhibit broad dispersal, most notably seen in the largest group, which includes representative samples extending from northern Mexico to Delaware. This work highlights the increasingly recognized geographic range of R. parkeri in the Americas and suggests a potential public health risk for these areas.
Publication Date
10-13-2021
Publication Title
Microbiology Spectrum
Publisher
American Society for Microbiology
Rights
This is a work of the U.S. Government and is not subject to copyright protection in the United States. Foreign copyrights may apply.
Recommended Citation
Allerdice MEJ,Paddock CD, Hecht JA, Goddard J, Karpathy SE.2021.Phylogenetic Differentiation of Rickettsia parkeri Reveals Broad Dispersal and Distinct Clustering within North American Strains. Microbiol Spectr9:e01417-21.https://doi.org/10.1128/Spectrum.01417-21
