Abstract
Strain S, a spotted fever group (SFG) rickettsia isolated from Rhipicephalus sanguineus ticks collected in Armenia, was identified. Microimmunofluorescence, sodium dodecyl sulfate-polyacrylamide gel protein electrophoresis and Western immunoblotting, PCR and then restriction fragment length polymorphism analysis, pulsed-field gel electrophoresis, and 16S rRNA gene sequencing were used to compare strain S with reference isolates. Strain S was found to possess proteinic, antigenic, and genomic patterns which were unique among SFG rickettsiae. Strain S is characterized by its high degree of pathogenicity for experimental animals, but its role as a potential human pathogen should be determined. The role of R. sanguineus ticks in the epidemiology of SFG rickettsiae is discussed.