Peculiarities of Humoral Immunity Formation in Medical Institution Employees Recovered from or Vaccinated against COVID-19 in Irkutsk.

We performed a seroepidemiological survey of the level and structure of population immunity to SARS-CoV-2 among employees of medical institution in the Irkutsk region during the COVID-19 pandemic. Seroprevalence assessment was organized from May 2020 to April 2021. The level of antibodies to SARS-CoV-2 was measured by ELISA. It was found that 139 (46%) of 299 examined workers were seropositive, including 50 (36%) vaccinated against COVID-19, 75 (54%) patients diagnosed with COVID-19, and 14 (10%) asymptomatic cases of SARS-CoV-2. The results obtained should be taken into account when predicting the dynamics of the epidemic process and organizing preventive (antiepidemic) measures, including vaccination.

[CONSTRUCTION OF A TEST-SYSTEM WITH NANOPARTICLES OF COLLOID SILVER FOR DETECTION OF PSEUDOTUBERCULOSIS AND INTESTINAL YERSINIOSIS FOR CAUSATIVE AGENTS IN DOT-IMMUNOASSAY].

AIM: Construction of an immunologic test-system for detection of causative agents of enteropathogenic Yersinia (Yersinia pseudotuberculosis and Y. enterocolitica) by dot-immunoassay. MATERIALS AND METHODS: Nenoparticles of colloid silver sized 5-9 nm were used as a marker of specific antibodies. IgG fraction was isolated from commercial antisera to Y. pseudotuberculosis (Ο:1) and Y. enterocolitica (Ο:3 and Ο:9). Testing of the obtained test-system was carried out on 20 strains of Y.pseudotuberculosis and Y. enterocolitica (10 of each species). RESULTS: Dot-analysis had a specific character and detected enteropathogenic Yersinia at a level of 5-105 - 8.106 CFU/ml (100 - 1000 CFU in sample). Wherein cross-reaction with heterologic studied microorganisms - Escherichia coli, Salmonella typhimurium, Shigella flexneri, Yersina pestis EV - as not observed. A possibility of simultaneous detection and serotyping of Y. enterocolitica is shown, that is necessary for confirmation of their epidemic significance. CONCLUSION: The developed test-systems allow to study micro volumes of the samples under study (1 µ1), are express (1.5 - 2h), highly sensitive and specific, technically simple and do not require the use of high-cost equipment, special training of the staff, may be successfully used in practical healthcar in laboratories with varying equiptment levels.

[PLAGUE IN MANCHURIA (1910-1911) AND EBOLA VIRUS DISEASE IN WEST AFRICA (2014-2015): COMMON PREREQUISITES FOR THE DEVELOPMENT OF EPIDEMICS].

The paper gives the results of a comparative analysis of the prerequisites for the emergence and spread of epidemics of particularly dangerous infections, by using plague in Manchuria (1910-1911) and Ebola virus disease in West Africa (2014-2015) as examples. Analysis of literature and archival data and online information could reveal a number of common factors and conditions, which substantially contributed to the epidemics. Organization of anti-epidemic (preventive) measures in cases of the threatening epidemic spread, of particularly dangerous diseases must be based on the minimization, of the influence of the specific factors and conditions, which facilitate disease transmission in a given area in a given time.

[Epidemiological situation and prophylaxis of zoonotic and natural-focal infectious diseases in Siberia and the Far East].

Analysis of zoonotic and natural-focal infectious disease morbidity in 2009 - 2011 in Siberia and the Far East is presented, and a complex of measures aimed at their prophylaxis is proposed. Analysis is carried out based on the data received by Reference Center of Monitoring of Natural-Focal Infection Causative Agents and Regional Center of Monitoring of I-II Pathogenicity Group Causative Agents at the Irkutsk Research Institute of Plague Control from departments and Centers of Hygiene and Epidemiology of Siberian, Far Eastern, 3 subjects of Urals Federal District and 5 Stations of Plague Control of Federal Service for Control in the Sphere of Protection of Consumers' Rights and Well-Being of Humans. In the morbidity structure in this region "tick-borne" infections were established to predominate--69.4%, among bacterial--yersiniosis dominates. Deterioration of epizootic situation on rabies is observed in the Republics of Tuva and Buryatia.

[Molecular-biological characteristic of Yersinia enterocolitica circulating in various regions of Russian Federation].

AIM: Complex characteristic by phenotype signs and main virulence genes of Yersinia enterocolitica strains circulating in various regions of Russian Federation. MATERIALS AND METHODS: 46 strains of Y. enterocolitica of 2 - 4 biotypes and 401 strains of Y. enterocolitica IA biotype isolated in 15 administrative territories of Russian Federation (Siberian, Far Eastern, Northwestern, Urals Federal Districts) from infected people, rodents, agricultural animals, birds, the environment were studied. Phagotyping was performed in the reference laboratory of the Pasteur Institute (Paris). All the Y. enterocolitica cultures were studied for the presence of ail, ystB and ystA genes by PCR method. Presence of virulence plasmid pYVwas determined by gel electrophoresis by T. Kieser method. RESULTS: 447 strains of Y. enterocolitica biotype 1A and 2 - 4 were studied. Most of the strains belonged to serotypes O:3; O:9; O: 5; O: 6,30; O:6,31; O:7,8. Phagotyping was performed for part of the strains. Phagotypes Xz and Xo were determined in biotype 1A strains. 2 - 4 biotype strains circulating in Siberia and the Far East were characterized by phagotype VIII, X3 that are present in other countries, and phagotype Xz that is spread only in Russia. Phagotypes IXa, IXb, II that are characteristic for strains from Canada, South Africa, Japan were not detected in Russian Federation. All the strains of 2 - 4 biotypes had ail and ystA genes. Most of the recently isolated strains had pYV. The only pathogenicity factor detected in 81.3% of biotype 1A strains including 14 strains from patients was ystB gene. These infections were accompanied by an expressed clinical symptomatology of enteritis and enterocolitis. CONCLUSION: Isolation of 1A biotype strains from patients necessitates execution of diagnostic studies of intestinal yersiniosis in patients with diagnosis "acute intestinal infection of undetermined etiology".

[Molecular genetic monitoring of Yersinia pseudotuberculosis using PCR O-genotyping].

Irkutsk PCR O-genotyping of 117 Yersinia pseudotuberculosis serotype O:1-O:4 strains isolated in Siberia and Far East was performed. These methods allowed both O-genotype and its variants (a, b, c) to be detected. It was demonstrated that three Y. pseudotuberculosis O-genotypes were circulated in Siberia (O:1a, O:1b and 0:3) and six genotypes (O:1a, O:1b, O:1c, O:2a, O:3 and O:4b) were circulated at Far East. Genotype O:1b dominates at both regions (87.8%). PCR-algorithm for identification of Y. pseudotuberculosis O-genotypes having epidemic significance was developed. The identification of the etiological agent O-genotype without bacteriological isolation of the stimulus is possible by PCR analysis of the clinical material.

[Genotyping of Yersinia pseudotuberculosis isolated in Siberia and Far East].

Genotypic characteristics based three main factors of pathogenicity (presence of resident plasmids [pYV, pVM], gene of toxin-superantigen ypm and nine genes for high pathogenicity island [HPI]) of 212 strains of Y. pseudotuberculosis isolated in Siberia and Far East were studied. It was shown that strains of Y. pseudotuberculosis with one of two variants of plasmids 82:47 MDa and 47 MDa (60.8% and 31.6% respectively) are predominated. Gene ypmA was detected in 96.2% of isolated strains. Eight strains had none of the ymp gene variants. HPI were detected in 96.2% of isolated strains. Obtained characteristics of Y. pseudotuberculosis allowed to determine the dominating genogroup pWYV+, ypmA+, HPI- (95.8% of strains) that cause systemic infection.

[Evaluation of the polymerase chain reaction effectiveness in the investigation of out-breaks of pseudotuberculosis]. / Otsenka éffektivnosti polimeraznoi tsepnoi reaktsii pri rassledovanii vspyshek psevdotuberkuleza.

Data on the investigation of pseudotuberculosis epidemic outbreaks with the use of the polymerase chain reaction (PCR), are presented. Specific fragments of Yersinia pseudotuberculosis DNA were detected in 81.25% of patients, in 46.83% of cases confirmed by the isolation of Y. pseudotuberculosis cultures. The study of washings from vegetables and equipment in vegetable stores and kitchens yielded positive results in PCR in 8.52% and the survey of rodents--in 3.85% of cases. In the course of the bacteriological study of these specimens 6 Y. pseudotuberculosis cultures were isolated: 3--from vegetable products, 1--from a Norway rat and 2--from house mice. The coincidence of the data obtained by bacteriological study and PCR showed that the latter method gave objective results, while being capable of ensuring rather rapid analysis. PCR should be regarded as a signal test for the bacteriological search of the definite infective agent in the material under study.

[Impact of Yersinia pseudotuberculosis on the in vitro production of cytokines by whole blood cells of donors]. / Vliianie Yersinia pseudotuberculosis na produktsiiu tsitokinov kletkami tsel'noi krovi donorov in vitro.

The impact of two plasmid (47, 82 MD), single plasmid (47 MD) and non plasmid Y. pseudotuberculosis strains, Y. enterocolitica (47 MD) as well as Y. pseudotuberculosis superantigen (YPM) on the production of interleukin-1 (IL-1), interleukin-6 (IL-6), interferon-alpha (IFN = alpha) and tumor necrosis factor alpha (TNF-alpha) by whole blood cells obtained from donors was studied. All Y. pseudotuberculosis and Y. enterocolitica strains stimulated the production of IFN-alpha, IL-1, IL-6 and TNF-alpha by whole blood cells, but considerably less than Y. pseudotuberculosis lipopolysaccharide and YPM. These data are indicative of the pathogenetic role played by 82 MD plasmid in manifestation of Y. pseudotuberculosis immunosuppressive properties. The maximum stimulation of the production of cytokines was observed under the action of YPM, which confirmed an important role played by this superantigen in the pathogenesis of Y. pseudotuberculosis.

[Mode of sample preparation for pseudotuberculosis laboratory diagnosis by polymer chain reaction method]. / Sposob podgotovki prob dlia laboratornoi diagnostiki psevdotuberkuleza metodom polimeraznoi tsepnoi reaktsii.

A mode of feces sample preparation was developed for polymerase chain reaction (PCR) assay. It was based on alkaline treatment of the material. This treatment killed the most part of indigenous microflora, whereas Yersinia survived, because it was relatively resistant to alkaline. The mode was tested using human feces artificially contaminated with Yersinia pseudotuberculosis. Positive responses in samples containing 10(3)-10(8) microbial cells per ml were obtained by PCR assay with Yersi and Yers2, Invl and Inv2, YP3 and YP4 primers. Diagnostic efficiency of PCR for patients, small mammals, and washings from environmental objects was 4.75, 1.66, and 2.12 times higher than diagnostic efficiency of bacteriological analysis of these samples, respectively. Positive results in PCR were obtained at the day of the material collection and treatment, whereas Y. pseudotuberculosis was isolated only after 8-20 days. Positive samples in PCR and in bacteriological analysis were found to coincide. A brief scheme of the Y. pseudotuberculosis laboratory diagnosis is suggested. According to this scheme, target-oriented bacteriological assay is performed only in those samples, in which preliminary PCR assay after 1-3 days of incubation gave positive results of Y. pseudotuberculosis DNA detection.

[Zoonotic infections in the central and southern ulusy of the Republic of Sakha]. / Zoonoznye infektsii v tsentral'nykh i iuzhnykh ulusakh Respubliki Sakha.

The serological survey of humans, as well as agricultural animals and rodents, for the presence of zoonotic infections, was carried out. Local inhabitants were shown to have contacts with the causative agents of pseudotuberculosis, enteric yersiniosis, tularemia, leptospirosis, Q fever, tick-borne rickettsiosis, chlamydiosis, toxoplasmosis. The immune stratum with respect to enteric yersiniosis was found to have a greater index, while the immune strata with respect to chlamydiosis, Q fever, pseudotuberculosis had the least indices. However, the indices of immune strata perceptibly varied in individual regions. The highest occurrence of antibodies to all above-mentioned zoonotic infections was registered in Megino-Kangalasskii, Amga and Neriungrinskii ulusy [correction of regions]. The probable sources of leptospirosis, toxoplasmosis and Q fever were agricultural animals, while the probable sources of enteric yersiniosis and leptospirosis were rodents.

[The epidemiological patterns of yersiniosis in the Republic of Sakha (Yakutia)]. / Epidemiologicheskie zakonomernosti iersiniozov v Respublike Sakha (Iakutiia).

On the basis of complex studies, carried out over the period of 21 years, the epidemiological characterization of Yersinia infections in the Republic of Sakha (Yakutia) is presented. The average monthly morbidity rate (per 100,000 persons) was 5.8 +/- 0.002 for pseudotuberculosis and 0.61 +/- 0.001 for enteric yersiniosis. In the time course of pseudotuberculosis morbidity 2 periods were established. The first period (1974-1987) was characterized by the prevalence of epidemic outbreaks with a pronounced spring-summer rise in morbidity, mainly among children aged 3-6 years and 7-14 years in closed groups. The reasons of these epidemic outbreaks were established. The second period (1988-1994) was characterized by sporadic morbidity with seasonal winter-spring and summer-autumn rises involving children of all age groups both in closed groups and at home. The main trends in the system of epidemiological surveillance on Yersinia infections were determined, depending on the level and character of morbidity.

[THe characteristics of the epidemic process of pseudotuberculosis infection in the southern and northwestern foci of Irkutsk Province]. / Osobennosti épidemicheskogo protsessa psevdotuberkuleznoi infektsii v iuzhnom i severo-zapadnom ochagakh Irkutskoi oblasti.

A long-term study of pseudotuberculosis epidemiology has revealed two independent foci in the south and northwest of Irkutsk Province, which differ in the level and pattern of morbidity, seasonal features, patients' age distribution, severity of a clinical course. Each focus is characterized by the clonal structure of the pseudotuberculosis bacillus, which is persistent in terms of the plasmid profile. Strains with the two plasmids 47 mD (pYV) and 82 mD (pVM) circulate in the southern focus, while those with one plasmid 47 mD (pYV) in the northwestern focus. The intensity of an epidemic process is not associated with the presence of the plasmid 82 mD (pVM). The presence of the latter statistically significantly determines the severity of the clinical course of pseudotuberculosis infection, which seems to be caused by the immunodepressive action of the plasmid pVM.