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Biomedical subjects

N M Balaeva

Publications and source records attributed to N M Balaeva.

15 recordsLinked to original sources
PubMed1991

[Serological demonstration of the detection of tick-borne rickettsial disease in Astrakhan Province].

Starting from 1978, noncontagious febrile diseases of unclear etiology, accompanied by pronounced headache, roseolous-papular eruptions, prolonged convalescence period, are registered in May-September in Astrakhan Province. These diseases can be effectively treated with chrolamphenicol. In 11 out of 12 sera obtained from such patients the complement fixation test with the antigens of rickettsiae causing tick-borne spotted fever, epidemic typhus, as well as Coxiella burnetii antigen, revealed the presence of antibodies (in 8 sera) only to the antigens of rickettsiae causing tick-borne spotted fever (R. akari, R. conorii, R. sibirica), or the titers of antibodies to these antigens were greater (1 serum), equal and lower (2 sera) in comparison with those of the antigens of rickettsiae causing epidemic typhus. The dynamics and values of antibody titers in 7 patients with the antigens of three rickettsial species of the tick-transmitted biotype indicated that the disease was related to tick-borne spotted fever.

Antibodies, Bacterial↗
PubMed1990

Properties in culture and persistence in cotton rats of the Rickettsia prowazekii vaccine strain E and its mutants.

Cultural properties and the capacity for persistence were studied in spontaneous erythromycin-resistant (E errSM), in induced erythromycin-resistant (E errI) mutants and in a virulent revertant (E Vir) of the vaccine strain E, as compared with parent vaccine strain E and standard virulent strain Breinl of Rickettsia prowazekii. Cultural properties of the strains were found to differ in passages in chick embryos (CE) and cultures of FL cells. Multiplication indices in CE of mutant E errI were significantly lower than those of other strains (E, E errSM, E Vir, Breinl). The multiplication rate in FL cells was found to be high in strains E errSM, Breinl, E Vir, being much lower in strains E errI and E. The capacity of the virulent revertant E Vir to persist in cotton rat (CR) was higher as compared with that of standard strain Breinl and significantly higher than that of the parent strain E. Low level carrier state of rickettsia was registered in CR infected with the mutant E errI.

Animals↗
PubMed1990

[Methods of isolation and polypeptide composition of membrane fractions of Rickettsia prowazekii].

The methods of cell lysis by lysozyme in tris-EDTA-sucrose with the consequent disruption of spheroplasts by the osmotic shock were used to obtain the total membranes from the intact or temperature-inactivated Rickettsia prowazekii. Detergents solubilization methods were used for analysis of outer membrane proteins. Sarcosyl insoluble material is shown to contain the main 134, 31, 29.5 and 25 Kd proteins, the minor 78, 60, 42, 17 Kd proteins, while the mixture of both membranes possess a more complex composition. Treatment of total membranes by the 2% octylglycoside results in elimination of the 31 Kd polypeptide. Inactivated Rickettsia can be used for isolation of the outer layer proteins diminishing the risk of working with this pathogenic microorganism.

Bacterial Outer Membrane Proteins↗
PubMed1990

[The rickettsial genome studied by DNA restriction analysis].

The restriction analysis of 6 Rickettsia prowazekii strains with the use of 8 restrictases (Cfr13I, EcoRI, HindIII, MSpI, MvaI, PstI, XhoI, BamHI) has been carried out. In the presence of considerable homology in the restriction pictures of DNA in these strains some differences in 1-2 fragments within the range of 8,000-20,000 nucleotide pairs have been established. The strains under study have been divided into two groups according to the character of differences in their restrictograms: the group of virulent typing strain Breinl (Breinl, G. Anan'ev) and the group of strain E with low pathogenicity (E, EVir, Katsinian). Differences in the restrictograms of DNA do not correlate with the virulence of R. prowazekii strains and the areas of their isolation.

DNA Restriction Enzymes↗
PubMed1989

[Electrophoretic and immunochemical characteristics of proteins of Rickettsia prowazekii strains of various virulence].

PAAG-electrophoresis of the isogenic pair of Rickettsia prowazekii strains E and Evir lysates demonstrate the similarity in polypeptide tracks. The different electrophoretic mobility of the Mr 30 Kd protein from these strains as compared with the mobility of analogous protein from the standard virulent Breinl strain is registered. In immunoblot experiments the specific rabbit antiserums obtained on the 30th day of infection with the Breinl, E or Evir strains demonstrate the presence of the different main antigens 60 Kd or 70 Kd. The difference evidently reflects the specificity of development of two forms of infection by the strains having different virulence. The surface tris-soluble antigens of Rickettsia prowazekii have the similar polypeptide contents and immunochemical properties. The main component of tris-soluble antigens Mr 130 Kd protein is not strain specific having the common thermolabile epitope.

Bacterial Proteins↗
PubMed1989

[Inactivation of concentrated biomasses of Rickettsia prowazekii].

The methods used for the sparing inactivation of highly concentrated R. prowazekii biomass and for the decrease of its infectious activity are described. These methods are recommended for use in experiments in the field of molecular biology, as well as for disinfection of different materials contaminated with rickettsiae. As conditions for complete inactivation, incubation at 50 degrees C for 1 hour without chemical disinfectants, treatment with 0.5% phenol solution at 30 degrees C for 12 hours and with 0.1% formaldehyde solution at 4 degrees C for 24 hours have been selected. Treatment with 0.5% phenol solution at 36 degrees C for 1 hour or incubation at 45 degrees C without the use of disinfectants ensures an essential decrease in the infectivity of the material if the work with viable infective agents is necessary. Ultraviolet irradiation for 1.5 hours and exposure to the action of 0.1-0.5% sodium azide are less effective.

Azides↗
PubMed1989

Methods for purification of Rickettsia prowazekii separated from the host tissue: a step-by-step comparison.

Two methods for purification of Rickettsia prowazekii strains E, E Vir, and Breinl grown in chick embryo yolk sacs are described. These methods combine either differential centrifugation or sucrose mix, centrifugation through sucrose cushion, 10 mmol/l MgCl2 treatment, filtration through a glass filter AP-20 and 2 cycles of verografin discontinuous density gradient centrifugation. The purification procedure including sucrose mix allowed to recover about 38-42% biologically active rickettsiae, a yield which was by 10% higher than that obtained by the method beginning at differential centrifugation. The rickettsiae free of host cell components preserved their infectious activity. The obtained biomass was suitable for immunological and biological characterization of Rickettsia prowazekii and for isolation of its total DNA.

Animals↗
PubMed1989

Restriction endonuclease analysis of the DNA of Rickettsia prowazekii vaccine strain E and its revertant.

The DNA of Rickettsia prowazekii vaccine strain E was analysed by restriction analysis with 17 endonucleases in comparison with its virulent revertant - Evir and the virulent reference strain Breinl. The DNA of cloned and uncloned strains showed identical restriction endonuclease patterns. In spite of stable differences in virulence, strains E and Evir displayed a totally identical DNA cleavage pattern indicating the absence of marked structural differences between their genomes. On the other hand 9 endonucleases showed differences in the restrictograms of the DNA strain Breinl as compared with strains E and Evir.

DNA Restriction Enzymes↗
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

[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↗