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N M Balaeva

Publications and source records attributed to N M Balaeva.

At least 37 records · Page 2Linked to original sources
PubMed1985

[Antibiotic sensitivity of the erythromycin-resistant strain E of Rickettsia prowazekii cultured in the vector's body].

Experiments on the laboratory cultures of lice infected by Weigl's method revealed that the spontaneous, erythromycin-resistant mutant of R. prowazekii strain E, adapted to the vector's organism, retained its resistance to erythromycin during 50 successive passages without the maintenance concentrations of this antibiotic. The above strain remained sensitive to tetracycline and levomycetin. Its level of sensitivity to the latter antibiotics was similar to that of R. prowazekii strains cultivated in the vector's organism for a long time.

Animals↗
PubMed1985

[Use of the immunofluorescence reaction for evaluating the immunological transformation in those inoculated with a chemical typhus vaccine].

The results of the serological examination of persons immunized with chemical typhus vaccine (CTV) are presented. The examination was carried out by means of the complement fixation test (CFT), the passive hemagglutination test (PHAT), the toxin neutralization test (TNT) and the immunofluorescence test (IFT). The acetone-fixed live culture of Rickettsia prowazekii, strain Breinl, served as antigen in IFT. If persons immunized with CTV showed positive titers in CFT, TNT and PHAT, the results of IFT were highly correlated with the CFT titers. In 6-12 months after immunization with CTV the titers of CFT, TNT and PHAT became negative, while the IFT titers remained positive for several subsequent years.

Antibodies, Bacterial↗
PubMed1982

[Production of the mutant E strain of Rickettsia prowazekii by mutagen exposure].

The possibility of obtaining the mutants of R. prowazekii, strain E, by exposing these organisms to the action of N-methyl-N-nitro-N-nitrosoguanidine was studied; this substance, used in doses of 5-10 micrograms, showed a mutagenic effect on rickettsiae suspended in physiological saline, after their exposure for 10-20 minutes at 37 degrees C. The mutants thus obtained proved to be resistant to erythromycin and rifampicin and were characterized by heterogeneity in the degree and stability of their antibiotic resistance. The effectiveness of selection was increased if mutagen-treated rickettsiae were selected after the first passage in chick embryos. The induced mutants differed from the original rickettsial strain by their lower infectiosity for chick embryos.

Animals↗
PubMed1981

[Luminescent-serologic analysis of the antigenic interrelationship between R. canada and classic representatives of rickettsiae of the typhus group].

The results of studying the antigenic relationships of R. canada, a new Rickettsia species, and classical Rickettsia species of the typhus group are presented. The study was carried out by luminescent serological analysis with the use of corpuscular antigens and the live infectious agent cultures. R. canada and Rickettsiae of the typhus group were similar in their antigenic structures; this, however, could be revealed only in the study of the live cultures of the infectious agents. The study of corpuscular antigens revealed unilateral relationship: R. prowazeki antigen could be detected with homologous and heterologous sera, R. canada antigen with homologous serum only. In the CFT and the agglutination test corpuscular R. canada antigen reacted with homologous and heterologous sera. The study of the live cultures of the infectious agents revealed that different R. prowazeki and R. typhi strains vary in the degree of their similarity to R. canada.

Agglutination Tests↗
PubMed1979

[Rickettsia conorii and prowazekii plaque study in a chick fibroblast cell culture].

The results of the study of plaques formed by R. conorii (strain M 1) and R. prowazeki (strain E and erythromycin-resistant strain E) in chick fibroblast cell culture are presented. In this study the tissue monolayer was inoculated with rickettsiae suspended in various media, and media of different composition were used in the nutrient cover and for cell cultivation. The maximum plaque formation was observed under the following conditions: the monolayer of chick fibroblasts (seeding density was not less than 375,000 cells per 1 sq. cm) was grown in medium 199 with 5-10% of fresh fetal or calf serum and inoculated with rickettsiae suspended in heart-brain infusion; the nutrient cover was prepared on the basis of Seakem agarose (USA) and contained medium 199 (without antibiotics) and 10% of fresh fetal or calf serum. In these conditions R. conorii formed plaques 2 mm in diameter, the first plaques being observed on day 6, and most of them on days 7-9; the both strains of R. prowazeki formed plaques 1 mm in diameter, the first plaques being observed on days 8-9, and most of them on days 10-13.

Animals↗
PubMedDate not supplied

[The need for a review of the procedure for the preventive vaccination of researchers working with Rickettsia prowazekii].

The analysis of the results of prolonged observations on the prophylactic immunization of employees working with R. prowazekii is presented. The necessity of the differentiated approach to the determination of the immunization schedule and the choice of vaccine is shown. The presence of specific antibodies (Ab) and the level of their titers have been found to be related to the degree of anti-infectious protection. The following characteristics indicate the presence of profound immunological transformation in vaccinees: complement-fixing Ab in titers 1:10 and more and/or immunofluorescent Ab in titers not below 1:180, Ab to protein in the hemagglutination test in titers not below 1:1000. These specific Ab and the level of their titers can be registered after the second injection of live combined typhus vaccine E and the third injection of chemical typhus vaccine. Cases of laboratory infection and their relationship to the character of immunization and the intensity of contacts with R. prowazekii virulent strains are discussed. Attention is drawn to the strict observance of professional safety rules.

Academies and Institutes↗
PubMedDate not supplied

[Cloning and expression in Escherichia coli of three Rickettsia prowazekii genes, coding outer membrane proteins].

Rickettsia prowazekii (virulent Breinl strain) random genomic DNA fragments were cloned in the lambda gt11 expression vector by using non-palindromic adaptors. Several immunoreactive clones were selected after screening 20,000 individual recombinant plaques with human convalescent serum. Some recombinants synthesized the complete 60 K protein, and others synthesized beta-galactosidase fusion polypeptides containing epitopes of 134 K protein of the R. prowazekii outer membrane. The amplified genomic library was screened with monospecific antibodies directed against abundant 31 K and 29.5 K outer membrane proteins. Several recombinant clones expressing full or part of 29.5 K polypeptide, and none expressing 31 K polypeptide were revealed. The serum of a patient convalescing from epidemic typhus did not react in western blot with recombinant 29.5 K protein.

Antibodies, Bacterial↗
PubMedDate not supplied

[Characteristics of DNA restriction fragment length polymorphisms of C. burnetti strains, isolated from areas of Russia].

The structural heterogeneity in Coxiella burnetii chromosomal DNA isolated in the European part of Russia from people, agricultural animals, and ticks has been studied. It is compared with the one of the European strains Henzerling and M44, the only genetically characterized strains up to date. The digestion of the total DNA by the restriction endonucleases BamHI, PstI, XhoI resulted in obtaining two types of restriction patterns. The ones for Henzerling and M44 differed from the restriction patterns of the Russian strains, while the latter proved to be identical. The obtained data are in proof of genetical homogeneity in the Russian group of strains. The group is different from the genomic group including Henzerling and M44. The fact is in proof of the genetical heterogeneity of the European population of coxiellae.

Animals↗
PubMedDate not supplied

[Genotypic characteristics of Rickettsia sibirica strains].

Six Rickettsia sibirica strains isolated in Siberia and Far East (Primorje) from various sources (patient, ticks D. nuttali, D. silvarum, H. concinna) at different time (1940-1980) were studied by the RFLP and DNA probe hybridization techniques. All studied strains were found to have the identical profiles of migrating fragments in restrictograms got by using a set of endonucleases (EcoRI, PstI, PvuII, Bg1I, XbaI, HindIII, MspI) and similar zones of hybridization with a DNA probe derived from Rickettsia prowazekii DNA. The obtained data point to a close similarity between the genomes of investigated Rickettsia sibirica strains. Long-term isolation of the genetically similar Rickettsia sibirica strains testifies to their constant circulation, thus apparently determining the stability of epidemiologic manifestation of tick-borne typhus fever of Northern Asia in the central part of its area (Siberia, Far East).

DNA Probes↗
PubMedDate not supplied

[The protective activity of individual proteins and immunogenic fractions isolated from Rickettsia prowazekii].

The immunogenic properties and protective activity of basic protein I and tris-soluble antigens isolated from R. prowazekii were analyzed in comparison with those of chemical typhus vaccine on the model of anti-infectious immunity in guinea pigs. The analysis revealed that purified protein I has protective activity for guinea pigs, which is less pronounced in protein I from strain E with weak pathogenicity than protein I from strains EVir and Breinl. The activity and immunogenic properties of tris-soluble antigens, especially antigen I, are comparable with those of chemical typhus vaccines in the parameters under study.

Animals↗