Real-time PCR validation to estimate the number of rickettsias in the biological material under study.

Using the example of the clinical strain of R. sibirica «Bayevo 105/87», the possibility of quantitative determination of rickettsias in clinical samples from patients with Siberian tick-borne typhus by real-time polymerase chain reaction (PCR-RT) was evaluated. Cultivation was carried out in the yolk sacs of developing chicken embryos, from which a piece of the yolk sac or chorion was taken.

Avidity of IgG to Rickettsia prowazekii and the presence of specific IgM in blood sera for retrospective analysis of the 1998 epidemic typhus outbreak in Russia.

The authors applied a new methodological approach based not only on the study of IgM/IgG to Rickettsia prowazekii in sera, but also on the estimation of the avidity index of specific IgG. The data allowed the authors to draw new conclusions about the 1998 epidemic typhus outbreak in Russia.

[Retrospective serological diagnostics of spotted fever group rickettsioses in high risk areas of Rickettsia conorii subsp. Caspia infection.].

723 blood sera from 537 patients of Regional Infectious Clinical Hospital, Astrakhan were obtained during high activity period of Rhipicephalus ticks (May-September 2015) and retrospectively studied for IgG/IgM to antigen of spotted fever group (SFG) Rickettsia. IgG and/or IgM to Rickettsia conorii were detected in 145 sera from 130 patients, and antibodies to R. sibirica (group-specific) were detected in 143 sera from 145.

New approaches in the systematics of rickettsiae.

The development of a formal order analysis (FOA) allowed constructing a classification of 49 genomes of family representatives. Recently FOA has been extended with new tools-'Map of genes,' 'Matrix of similarity' and 'Locality-sensitive hashing'-for a more in-depth study of the structure of rickettsial genomes. The new classification confirmed and supplemented the previously constructed one by determining the position of str.

Comparison of genomes of strains using formal order analysis.

The  strain NL3262 was isolated during the Q fever outbreak in the Netherlands in 2007-2010. Formal-order analysis (FOA) was used to study the similarity of the genome (chromosome and plasmid) of this strain with the genomes from other strains. Chromosomes from ten strains and eight plasmids were studied with FOA tools such as 'Map of genes' and 'Matrix of similarity.