Isolation of Rickettsia helvetica from ticks in Slovakia

Summary. – to date, only three rickettsial species have been found in ticks in Slovakia by serological and/or molecular-biological techniques, namely Rickettsia slovaca , Candidatus rickettsia IrS, and Rickettsia raoultii . recently, we succeeded in isolation of the forth species, Rickettsia helvetica from Ixodes ricinus , the most frequent tick in Slovakia. The isolation, positive for 10% of tested ticks, was performed on Xtc cells by the shell-vial technique, Gimenez staining and light microscopy. The infected cell cultures contained rod-shaped particles morphologically identical to rickettsiae. The isolation was confirmed by direct detection of afragment of the R. helvetica gene for citrate synthase in the positive ticks by Pcr and its subsequent cloning, sequencing and comparison with the database. Keywords: rickettsia helvetica; isolation; Ixodes ricinus; Slovakia * corresponding author: e-mail: didier.raoult@gmail.com; phone: +33-491324630. Abbreviations: SFG = spotted fever group; Xtc =