Vol 86, No 6 (2009)

Aim. To study pathogenic characteristics of B.pertussis strains isolated from patients during different periods of pertussis infection epidemic process. Materials and methods. Strains of B.pertussis isolated in Moscow during 1967 — 1971, 1980 — 1985, and 2001 — 2005 were studied. Nutrient media: Bordet-Gengou blood agar, casein-charcoal agar. Animals: mice – F1 hybrids (CBA x C57BL6). Pathogenic characteristics of strains were studied by assessment of virulence (LD50), leukocytosisstimulating (LS units) and histamine-sensitizing (HSD50) activities of cultures. Genotyping was performed using standard equipment and reagents for DNA isolation, amplification, sequencing and detection of results. Results. On the sample of 164 strains, pathogenic and genotypic characteristics of B.pertussis populations circulated during 1967 — 1971, 1980 — 1985, and 2001 — 2005. Majority of B.pertussis strains isolated in 1967 — 1971 and strains circulated during current phase of epidemic process were virulent (80.75% and 81.8% respectively) and had significant leukocytosis-stimulating and histamine-sensitizing activity, whereas strains isolated from patients with pertussis in 1980 — 1985 characterized by lower virulence and toxicity. Genotyping showed strains carrying «non-vaccine» allele ptxA1, which emerged in the middle of 1970s, totally displaced strains with «vaccine» alleles ptxA2 and ptxA4. Conclusion. Adaptive changes of B.pertussis driven by increased vaccination coverage involve both ptxA gene and pathogenic characteristics of infectious agent in the range of genotypically homogenous population with domination of strains, which have high levels of virulence and toxicity.

Aim. To analyze prevalence and variability of Legionella strains isolated in town Verkhnaya Pyshma located in Sverdlovsk region during prophylactic surveillance of potentially dangerous water objects in 2007 — 2008. Materials and methods. Sequencing of mip gene was conducted for identification of species of Legionella . Multi-locus sequence typing was used for describing of allelic profiles of Legionella pneumophila strains. Results. Five firstly identified on Russian territory strains of Legionella species were deposited in institute’s collection. Sixty-three strains of L.pneumophila belonging to 28 sequence types were characterized. Relation between strains isolated in industrial building and from water supply system was demonstrated. Conclusion. Observations made on the basis of study of L.pneumophila strains isolated from cooling stacks of industrial plants confirmed potential danger of these objects as a source of dissemination of Legionella infection.

Aim. To assess the consistency of technological process of manufacture of DTP vaccine’s pertussis component on the basis of its immunogenicity using Shewhart’s cards. Materials and methods. Published data of domestic plants belonging to public corporation Mechnikov «Biomed» and Ufa branch of scientific-production organization «Immunopreparat» ingressed in «Microgen» enterprise were used. Immunogenicity of DTP vaccine pertussis component was studied. Results. It was revealed that technological process of manufacturing of DTP vaccine’s pertussis component on production plants was not always in statistically controlled state. Conclusion. Obtained data showed that it is reasonable for quality control departments of manufacturing plants to use Shewhart’s cards and methods of statistical management of technological processes for assessment of state of the latter.

Aim. To study the magnitute of antitoxic immunity against diphtheria in different age groups of Rostov-on-Don city and Rostov region population. Materials and methods. Antitoxic immunity against diphtheria was studied in children 3 — 15 years old (661 persons) and adults 16 — 59 y.o. (893 persons), which were tested during 2003 — 2007 using direct hemagglutination assay manufactured by Mechnikov Scientific Production Association «Biomed» (Moscow). Results. Proportion of children 3 — 15 y.o. seropositive to diphtheria was 98.6±0.5%. Children aged 3 years and 4 — 6 years were identified as a risk group for diphtheria as they had highest proportions of non-immune persons. Proportion of immune to diphtheria in adults was 94.4±0.8%. Maximal level of protection was observed in persons aged 16 — 17 and 18 — 19 years, in which the proportion of seropositive persons was 99.1 — 100%. Persons ≥50 years old formed group of risk because persons with low or moderate titers of antitoxin were identified in this age group mostly. Conclusion. Obtained results provide evidence on enough high level of protection of Rostov-on-Don city and Rostov region population against diphtheria. Group of increased risk comprised of persons aged 3 — 6 years and >50 years.

Aim. To engineer attenuated Bordetella pertussis strain producing non-toxic immunogenic derivative of pertussis toxin (toxoid KT). Materials and methods. Cloning, site-directed mutagenesis, allelic exchange as well as methods for determination of immunobiological characteristics of toxoid KT were used. Results. Attenuated B.pertussis strains 5 and 35 containing mutant operon ptx and gene of resistance to canamycin were engineered. Recombinant bacteria retained marker of resistance to canamycin as well as structure of mutant operon during cultivation on growth media and long-term survival in lung of laboratory mice. Immunobiologic characteristics of attenuated B.pertussis were studied. Conclusion. Intranasal immunization of laboratory animals with live attenuated B.pertussis 5 and 35 provides protection from infection with virulent B.pertussis strain, which is comparable with efficacy of standard whole-cell vaccine.

Aim. To study the effect of Enterobacter cloacae thermolabile enterotoxin (LT-enterotoxin) on different arms of immune system of mice. Materials and methods. Proprietary clinical strain E.cloacae 258 was used and intraperitoneal inoculation of outbred white mice with LT-enterotoxin-producing E.cloacae comprised experimental model. Phagocytic and lysosomal activity of peritoneal macrophages as well as level of APC to sheep erythrocytes were measured, spontaneous and induced NBT tests were also performed. Results. Pleiotropic immunotoxic effect of LT-enterotoxin of studied bacteria was established, which characterized by suppres- sion of antigen-presenting and antigen-processing functions of macrophages, stimulation of mitotic activity of lymphocytes, decrease of activity of hexose monophosphate shunt enzymes in peritoneal macrophages as well as abnormalities in formation of specific B-lymphocytes. Conclusion. Obtained data allowed to reveal separate steps in pathogenesis of infectious process caused by LT-enterotoxinproducing bacteria from Enterobacter genus.

Lypopolysaccharides of gram-negative bacteria can interact with TLR4 with subsequent formation of atheromas. Mutational deletion of TLR4 decreases risk of development of atherosclerosis. Other bacterial ligands, in particular, peptidoglycan as well as endogenous ligands reacting with TLRs and emerging in microorganism under the action of stress factors can contribute to induction of atherosclerosis. It has been concluded, that reactions initiated by interaction of TLRs with exogenous and endogenous ligands lie in the basis of atherosclerosis pathogenesis.