Development and application of an RT‒PCR assay for the identification of the delta and omicron variants of SARS-COV-2.

The emergence of mutations in the coronavirus genome provides opportunities for occurrence new strains with higher transmissibility, severity and duration of the disease poses. In 2020, a new variant of the coronavirus SARS-COV-2 - Delta was identified in India. This genetic variant has spread rapidly and became dominant in many countries, including Russia. In November 2021, a new outbreak of COVID-19 occurred in Africa driven by a variant SARS-COV-2 named later Omicron. Both variants had increased transmissibility compared to previously encountered variants and quickly, replacing its around the world. To promptly monitor the epidemiological situation in the country, to assess the spread of dominant genetic variants of the virus and to take appropriate measures, we have developed an RT‒PCR reagent kit for the identification of Delta and Omicron by detecting a corresponding combination of major mutations. The minimum set of mutations was chosen which allows to differentiate Delta and Omicron variants, in order to increase the analysis productivity and reduce costs. Primers and LNA-modified probes were selected to detect mutations in the S gene, typical for the Delta and Omicron. Similar approach can be implemented for the rapid development of assays for differentiating important SARS-COV-2 variants or for other viruses genotyping for epidemiological surveillance or for diagnostic use in order to assist in making clinical decisions. It was demonstrated that the results of VOC Delta and Omicron detection and their typical mutations were concordant with genotyping based on WGS results for all 847 samples of SARS-CoV-2 RNA. The kit has high analytical sensitivity (1х103 copies/mL of SARS-CoV-2 RNA) for each of the detected genetic variants and possesses 100% analytic specificity for microorganism panel testing. The diagnostic sensitivity (95% confidence interval) obtained during pivotal trials was 91.1-100% for Omicron and 91.3-100% for Delta, while the diagnostic specificity with a 95% confidence interval was 92.2-100%. The use of a set of reagents in combination with sequencing of SARS-CoV-2 RNA as part of epidemiological monitoring made it possible to quickly track the dynamics of changes in Delta and Omicron prevalence in the Moscow region in the period from December 2021 to July 2022.

[Gene Polymorphism of the c-fms, ITGB3,CCR2, and DBH genes in the populations of old believers of the Tyumen oblast and Russian residents of Novosibirsk].

Old Believers of the Tyumen oblast have been studied compared with a control sample of Russian residents of the city of Novosibirsk. The former are a unique subpopulation, which has been relatively isolated from the rest of Russians in central and northern regions of Russia due to religious reasons since the middle of the 17th century. Polymorphisms in the genes for glycoprotein ITGB3, dopamine-ß-hydroxylase (DBH), and chemokine receptor CCR2 and two mutations in the c-fms gene have been analyzed. The populations are only similar in the c-fms indel. The frequencies of the rare alleles of CCR2, ITGB3, and 3'UTR of c-fms in the Old Believers are lower than in the sample of Novosibirsk Russians, and the rare allele of DBH is more frequent. A significant negative correlation is observed between DBH and CCR2 (r =-0.88; df = 4; P < 0.023). Apparently, these differences are related to the long-term isolation of Old Believers. This assumption is consistent with the fact that the levels of heterozygosity for most loci in Old Believers are lower than in Novosibirsk Russians.