Detection of a new species of Rickettsiae in the ticks of Ixodes persulcatus in Russia

Genetic analyses (polymerase chain reaction and nucleotide sequence test) have been used to describe a new species of Rickettsiae in the ticks Ipersukarus in Russia. This species is named as Rzckettsia tarasevichiae after Academician of the Russian Academy of Medical Sciences Irma Vladimirovna Tarasevich, Head of the Laboratory of Rickettsial Ecology, N.F.Gamaleya Research Institute of Epidemiology and Microbiology. A total of 317 Ipersukatus imagoes were collected in the regions of the Urals, Western Siberia, Eastern Siberia, and Far East in the spring of 2001 and 2002. The authors detected R. tarasevichiae in 25.5 +/- 2.4% (87/317) of the examined I. persulcarus ticks, from 3.8% in the Novosibirsk Region (Western Siberia) to 56.8% in the Primorye Territory (the Far East). This is the first detection of the Rickettsiae in the ticks of the genus Ixodes in Russia. Conceivably, the spread of this Rickettsia species coincides with the area of I. persulcatus that inhabits the biotopes of southern taiga and mixed forests in Eurasia from the western frontier of Russia to the Far East. The nucleotide sequences of the fragments of gene 165 of pRNA and citrate synthctase of this species of Rickettsiae have been declared at the GenBank under numbers AF503168 and AF503167, respectively. Its most phylogenetically close species of Rickettsiae R. canadenss (69% homology in terms of the gene of citrate synthetase and 98% homology in terms of gene 165 of pRNA) which is responsible for cases of acute cerebral vasculitis in Northern America. This requires further studies of a possible role of R. tarasevichiae in the pattern of tick-borne infections recorded in the area of I. persulcatus.