ASTRAKHAN FEVER RICKETTSIAE - ANTIGENIC AND GENOTYPIC ANALYSIS OF ISOLATES OBTAINED FROM HUMAN AND RHIPICEPHALUS-PUMILIO TICKS

Two spotted fever group rickettsia strains, A-108 and A-167, were isol ated from the hemolymph of Rhipicephalus pumilio ticks collected in th e Astrakhan region of Russia, which is area endemic for Astrakhan feve r. These tick isolates were compared with a strain isolated from a pat ient suffering from Astrakhan fever and with reference spotted fever g roup rickettsiae strains. New tick isolates and the human strain were identical in their serologic, antigenic, and genetic characteristics b y several methods: microimmunofluorescence, protein gel electrophoresi s with immunoblotting, polymerase chain reaction followed by restricti on endonuclease fragment length polymorphism analysis, and pulsed-fiel d gel electrophoresis (PFGE). Astrakhan fever rickettsiae were found t o be serologically and antigenically similar to Israeli spotted fever rickettsiae. Both of them probably belong to a single Rickettsia conor ii pathotype complex. Only PFGE pattern analysis could clearly discrim inate Astrakhan fever rickettsiae from other isolates.