PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF SPOTTED-FEVER GROUP RICKETTSIAE ISOLATED FROM CATALAN RHIPICEPHALUS-SANGUINEUS TICKS

Eighty-nine Rhipicephalus sanguineus ticks and 21 Rhipicephalus bursa ticks collected in Catalonia were tested by the hemolymph test to esta blish their infection rate with spotted fever group rickettsiae. By Gi menez staining, 11.2% of the R. sanguineus isolates and 0% of the R. b ursa isolates were found to contain rickettsia-like organisms, Six spo tted fever group rickettsial strains (Bar29, Bar31, Gir4, Tar1, Tar2, and Tar3) were isolated from these ticks and were characterized by phe notypic and genotypic analyses, PCR followed by restriction fragment l ength polymorphism analysis showed that the six strains were identical and were characterized by the same restriction profiles as a strain, Mtu5, previously isolated from Rhipicephalus turanicus ticks in the So uth of France, Microimmunofluorescence serotyping, sodium dodecyl sulf ate-polyacrylamide gel electrophoresis of the purified organisms, and Western blot (immunoblot) assay with mouse polyclonal sera confirmed t his observation, Pulsed field gel electrophoresis of the whole genome of three of the strains showed that, although closely related, the pro file of Tar1 was slightly different from that of the Bar strains. Phyl ogenetic analysis showed that this new rickettsial sero- and genotype, which will be named the ''Catalan strain,'' is closely related to Ric kettsia massiliae. This strain shows an unexpected resistance to rifam pin, The epidemiological implications of these findings are considered .