[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 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.

[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.

[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.

[The effect of ultrahigh-frequency electromagnetic radiation on learning and memory processes].

Low-intensity electromagnetic field (12.6 cm, 2375 MHz, power density 1 mW/cm2) produced retrograde amnesia in the rat passive avoidance test. No effect was registered of microwave irradiation on the open field behavior and the pain sensitivity.

[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.

[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.

[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.

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 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.

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.

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.

[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.

[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 sensitivity of a number of cell cultures to different strains of Rickettsia prowazekii].

The sensitivity of some cell cultures to different R. prowazekii strains (strain E with low pathogenicity, virulent strain Breinl, strains ERifRI and EVir) has been studied with a view to the selection of an adequate culture for growing these strains and the study of their biological properties. Experiments on titration in cells have revealed that 6- to 7-day primary and secondary irradiated quail fibroblasts and human amnion cells FL show the maximum sensitivity to all strains under study, comparable to that of chick embryos.

[Infectivity and sensitivity to antibiotics of Rickettsia prowazekii mutants of the low-pathogenic strain E cultured in chick embryos].

Selection of mutants of a low pathogenic strain E of R. prowazekii is a trend in genetic investigation of this Rickettsia species and one of the approaches to stabilizing the strain avirulent properties with a purpose of using in vaccine prophylaxis of typhus. The mutants of R.

[Homology between the ribosomal and RNA-polymerase genes of E. coli and vaccine strain E of Rickettsia prowazekii].

The pIB52 plasmid contains the ribosomal rp1A, J, K, L and RNA-polymerase genes rpo C, B of Escherichia coli. No homology has been found between the plasmid used as a molecular probe and the chromosomal DNA from Rickettsia provazekii in the blot hybridization experiments.

[Biological properties of antibiotic-resistant mutants of the mildly pathogenic Rickettsia prowazekii E strain].

The use of R. prowazekii strain E with low pathogenicity as live vaccine against exanthematous typhus is limited by its high specific reactogenicity, which is probably due to the reversion of the virulence of the strain. One of the approaches to the stabilization of the avirulent properties of strain E is obtaining its mutants with stable decreased pathogenic properties.

[The library of Rickettsia prowazekii genes].

The DNA of Rickettsia provazekii strain E was cleaved by PstI restriction endonuclease under the conditions of partial restriction. The fragments were inserted into the PstI site of pBR325 and cloned in this plasmid. E.