Аңдатпа
Purpose. To study distribution, species diversity and genetic variability of rickettsiae in Dermacentor spp. from the Western Siberia and Northern Kazakhstan. Material and methods. Samples from 571 Dermacentor ticks (406 Dermacentor reticulatus, 136 Dermacentor nuttalli, 21 Dermacentor marginatus, and 8 Dermacentor silvarum) were examined for the presence of Rickettsia spp. DNA using nested PCR. The species of rickettsiae was determined by species-specific PCR and/or sequencing of gltA gene fragments. For a number of R. raoultii samples, the sequences of the ompA (3266 bp) and ompB (4852 bp) gene fragments were additionally determined. Results. DNA of four Rickettsia species and a new genotype Rickettsia spp. Ko-97-Dr, which cannot be assigned to any of known species, were found in examined ticks. All tick species were most commonly infected with R. raoultii; the infection rate varied from 47.0% to 86.8%. Rickettsia sibirica DNA was found in 16.1—45.7% of D. nuttalli at three sites in the Republic of Altai. DNA of Rickettsia aeschlimannii, Rickettsia aeschlimannii-like, «Candidatus Rickettsia tarasevichiae» and a new genotype Rickettsia sp. Ko-97-Dr were found in single D. reticulatus and D. marginatus. Based on the analysis of the gltA gene fragment, seven haplotypes of R. raoultii were identified, four of which corresponded to previously described genotypes. The analysis of long fragments of the ompA and ompB genes of R. raoultii samples showed the presence of three genetic groups corresponding to different genotypes for the gltA gene. Conclusion. In Dermacentor spp., both typical and atypical species of Rickettsia spp. were found. The existence of natural foci of STT in the Altai Republic was shown. Based on the analysis of the variable surface protein genes and conserved gltA, the existence of three genetic groups of R. raoultii was shown.