Download Detection of Bacteria Rickettsia rickettsii, Causative Agent of Rocky

Detection of Bacteria Rickettsia rickettsii, Causative Agent of Rocky Mountain Spotted
Fever, in American Dog Ticks Using Polymerase Chain Reaction
Sasse, Michaela, Oaklee Abernathy, Jenna Ball, Yasuhiro Kobayashi
Department of Biological Sciences, Fort Hays State University
Background and Objective
Rocky Mountain Spotted Fever (RMSF) is a bacterial infection caused by the bacteria Rickettsia
rickettsii and transmitted in the American Dog Tick. The prevalence of the RMSF and R.
rickettsii is not well-characterized in Western Kansas. The objective of this study was to
examine the incidence of R. rickettsii in American Dog Ticks using the polymerase chain
reaction.
Method
The DNA was isolated from 50 ticks collected from nine grazing horses during summer 2015
and screened for R. rickettsii using primers for 16s rRNA and genes encoding two outer
membrane proteins (omp) using polymerase chain reaction.
Results
Of the screened ticks, only one sample had positive expression for the RR 16s primer, omp A
primer, and omp B primer. The amplicon for 16s rRNA was detected in 14 samples, but the
corresponding omps were not detected.
Discussion and Conclusions
Presence of the amplicon for the 16s rDNA and corresponding omps suggest the presence of
Rickettsia rickettsii. As the 16s rRNA amplicon was expressed in some samples without
corresponding omps, the species present is not likely Rickettsia rickettsii. Given that all ticks
were collected from horses grazing in the same pasture, the prevalence of some form of
Rickettsia species is relatively high in American Dog Ticks screened in this study.
Grant Support
This project was partially supported by a grant (P20GM103418) from the Kansas IDeA
Networks of Biomedical Research Excellence (K-INBRE) of the National Institutes of Health
(NIH). This project was also supported through the Fort Hays State University Undergraduate
Research Experience program.