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Gene-specific silencing refers to a phenomenon in which expression of an individual gene can be specifically repressed by different mechanisms on the levels of transcription, RNA splicing, transport, degradation in nuclei or cytoplasm, or blocking of translation. In different species gene-specific silencing was observed by expression or injections of antiparallel double-stranded RNA formed by a fragment of mRNA and antisense RNA. Here we show a potent and specific gene silencing in bacteria by expression of RNA, that is complementary in a parallel orientation to Escherichia coli lon mRNA. Moreover, the expression of parallel RNA is more effective at producing interference than expression of antisense RNA corresponding to the same mRNA region. Both effects of interference mediated either by parallel RNA or antiparallel RNA gradually decrease up to the 40th generation. Together with in vitro nuclease protection studies these results indicate that a parallel RNA duplex might be formed in vivo and both types of duplexes, antiparallel or parallel, can induce gene-specific silencing by similar mechanisms.There has been dramatic recent progress in uncovering the gene-specific silencing in a number of organisms (1-3). Several lines of evidence suggest that dsRNA 1 is the effector molecule responsible for RNA-mediated silencing or co-suppression. dsRNA is formed by mRNA and antisense RNA, that corresponds to the non-coding strand of the same gene. However, in experiments on Caenorhabditis elegans it was demonstrated that injections of gel-purified antisense RNA corresponding to an abundant transcript is less active at producing interference than in vitro annealed dsRNA samples (1). The purification was performed to remove the traces of dsRNA from in vitro synthesized RNA preparations because of the nonspecific activity of RNA polymerases.It was concluded that the observation of co-suppression and RNA interference uncovered the existence of a novel cellular mechanisms for regulation of gene expression (2, 4). The phenomenon has been described in fungi, protozoa, plants, invertebrates, and vertebrates (5-10). This suggests a evolutionary conservation of the physiological mechanisms involved.The mechanisms of RNAi remain largely unknown. It was concluded that RNAi and co-suppression work by an equivalent core mechanism produces decrease or elimination of a target mRNA transcript (2,3,4,6). In experiments on gene silencing ("quelling") in Neurospora crassa it was shown that in the mutant defective in quelling the gene specifying RNA-dependent RNA polymerase was affected (5). The genes involved in RNA degradation also could be connected with RNAi (12). It was considered that RNAi mechanisms might operate at the level of transcription and involve proteins of the polycomb complex (13). But recently it was clearly demonstrated that this transcriptional cosuppression mechanism is distinct from RNAi and involve homology recognition at the DNA level (14). The fact demonstrates that although the phenomenology of gene-specific silenc...

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Relevance. The Sverdlovsk district is a tense natural focus for Lyme borreliosis (LB) with a constantly recorded incidence that exceeds these indicators in the Russian Federation and the Ural Federal region several times. LB is registered on 56 of 59 administrative territories of the district. Currently, the count of LB in the Russian Federation includes both infections caused by Borrelia burgdorferi sensu lato group Borrelia and infections caused by Borrelia miyamotoi sensu lato group Borrelia.Aim. To characterize the epidemic process of LB in the territory of the Sverdlovsk district over a 20-year period (2002–2021).Materials and methods. The paper uses data from federal and regional statistical observations, reporting materials of the Department of Rospotrebnadzor in the Sverdlovsk district for 2002–2021, methods of statistical analysis.Results and discussion. During the follow–up period (2002–2021), the incidence rate of BL in the Sverdlovsk district exceeded the average long-term level in the Russian Federation by almost 3 times, and in the Ural Federal region – by 1.8 times. Among the mechanisms and ways of transmission of LB pathogens, the vector-borne mechanism dominated (84.5%), the share of the unidentified pathway was 15.4%, alimentary (when using raw goat's milk) – 0.1%. The duration of the epidemic season for LB in the district was 10 months (from March to December) with a peak incidence in June. Cases of LB were registered among people of different ages, with a predominance in the group of 60 years and older (39.1%). An analysis of the distribution of people with LB by social composition showed that pensioners prevailed among them – 36.3%, officials made up 27.8%, unemployed – 14.1%. Among the cases, a high proportion of schoolchildren and children under 7 years old were noted. It was found that erythematous and non-erythematous forms of LB are registered in the district, with a predominance of erythematous (64.5%). The main etiological agent of the erythematous form is Borrelia garinii, while the non-erythematous form is Borrelia miyamotoi and B. garinii. In the general structure of morbidity, the number of cases of LB is largely determined by the city inhabitants (92.9%). There were no fatal outcomes in LB in the territory of the district during the studied period.Conclusions. Due to the lack of vaccination of LB worldwide, the only strategy to reduce the incidence of LB is non-specific prevention and timely diagnosis of the disease, including data from epidemiological history, clinical and laboratory diagnostics. The long-term clinical and epidemiological and laboratory studies conducted by us in the Sverdlovsk district allowed us to characterize the main manifestations of the epidemic process of LB and to improve the diagnosis of the disease.

Relevance. Despite the ongoing program of mass vaccination of tick-borne encephalitis (TBE) for more than 20 years in the Sverdlovsk district, the incidence rate of TBE continues to exceed the average in Russia and the Ural Federal region.Aim. To analyze the main indicators of the manifestation of the epidemic process of TBE in the territory of the Sverdlovsk district under the conditions of planned vaccination over a 20-year period (2002–2021).Materials and methods. The article uses data from federal and regional statistical observations, reporting materials of the Department of Rospotrebnadzor in the Sverdlovsk district for 2002-2021, methods of statistical analysis.Results and discussion. During the study period (2002-2021), 3861 cases of TBE were registered in the Sverdlovsk district, while the highest incidence rate was detected in 2005 – 10.1 per 100 thousand population, and the lowest in 2020 – 1.0 per 100 thousand population. The share of the vector-borne mechanism was 78.4%, the unidentified path – 20.1%, alimentary – 1.5%. Analysis of the seasonal distribution of cases of TBE showed that the incidence is recorded from April to November. Cases of TBE were recorded in all age groups, including the child population. Most often, people aged 60 years old and older (24.6%) were ill with TBE. Among the children's population, the largest share fell on children aged 7–14 years (5.4%). Men of working age prevailed among the patients (66.0%). TBE was mainly registered among the unvaccinated population (81.5%) with a predominance of urban (86.1%). Officials predominated among the sick persons – 29.8%, pensioners made up 22.3%, unemployed – 19.8%. Persons whose work is professionally connected with the forest made up only 0.6%. The ongoing program of mass vaccination of TBE has led to a decrease in the proportion of severe and moderate forms of diseases (focal – 9.8% and meningeal – 24.0%) and an increase in the proportion of febrile (33.8%) and atypical forms (32.4%). Deaths during the studied period were recorded mainly among the adult unvaccinated population.Conclusions. The Sverdlovsk district continues to be a tense natural focus of TBE with a constantly recorded incidence among contingents of different age and social groups. In the absence of highly effective etiotropic drugs for the treatment of TBE, the only strategy for reducing the incidence of TBE, the development of severe forms and deaths in the territory of the Sverdlovsk district is mass vaccination of the population.