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Генетическое типирование Rickettsia akari

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Infekciâ i Immunitet: Russian Journal of Infection and Immunity






Rickettsia akari is an obligate intracellular bacterium that causes smallpox rickettsia. Rickettsia akari is an atypical member of the rickettsia spotted fever (SFG) group because it circulates in gamasid mites; however, only limited data are available regarding the degree of genetic diversity of R. akari isolates. We examined 13 isolates of R. akari isolated from humans, rodents, and ticks in the United States, the countries of the former USSR, and the former Yugoslavia for the period from 1946 to 2003 for diversity in the composition of tandem repeats (TR) and intergenic regions (IGR). Using the Tandem Repeat Finder software (http://tandem.bu.edu) to search for tandem repeats Tandem Repeat Finder (http://tandem.bu.edu), the 1.23 Mb genome of the R. akari Hartford CWPP strain was analyzed ; 374 different TRs were found, ranging in size from 1 to 483 bp. and the number of copies TR ranging from 21 to 1.9, respectively. No dimensional polymorphism was found among 11 TRs out of 5 open reading frames and 6 IGRs. Eighteen non-TR IGRs were amplified and sequenced from all isolates totaling 5995 bp. (0.49%) chromosomes of the Hartford CWPP strain. Three point mutations (SNPs) were found in two IGRs, which made it possible to separate five isolates of R. akari from the Ukrainian SSR from eight other isolates. In conclusion, it should be noted that this study is the first description of genetic diversity among R. akari isolates from different geographic regions. Further study of genetic diversity is necessary for a more accurate understanding of the geographical distribution of R. akari and the epidemiology of smallpox rickettsiosis.


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