PubMed Health⌕ Search

Biomedical subjects

I V Tarasevich

Publications and source records attributed to I V Tarasevich.

At least 19 recordsLinked to original sources
PubMed2001

[New and emerging rickettsial and bartonella infections].

There have been recently reports on over 10 new and resurgent rickettsioses and bartonelloses in different countries, which reflects both socioeconomic processes in society and a higher methodological level of indication and identification of causative agents. In 1991, the author' laboratory, N. F. Gamaleya Research Institute of Experimental Medicine, Russian Academy of Medical Sciences, established the etiology of the new rickettsiosis Astrakhan spotted fever. It separated and studied 2 strains of Rickettsia sp. nov. from patients and 8 ones from the carrier the Ixodes tick Rhipicephalus pumilio. It is suggested that the natural focus has transformed to the anthropurgic one due to technogenic environmental pollution. The annual increase in morbidity rates (2000 cases in 1983 to 2000) and its area are a challenge to public health care and medical science. The paper presents data on the new bartonellosis cat-scratch disease (caused by Bartonella henselae) detected not only in Russia. There is also information on tick-borne rickettsiosis, epidemic typhus, and trench fever as resurgent infections.

Bartonella↗
PubMed2000

[Determination of Ehrlichia genome size by pulse gel electrophoresis].

Ehrlichia infections are more and more common in the USA and Europe. The genetics and genome organization of Ehrlichia are little studied due to great difficulties in cultivating these bacteria. Pulse gel electrophoresis was first used to determine the sizes of a genome of 3 representatives of the genus Ehrlichia. The sizes of a genome was established for E. sennetsu (881 kb), for E. risticii (867 kb), E. chaffeensis (1,236 kb).

DNA Fragmentation↗
PubMed2000

[Distribution of biological particles in two-phase systems of water soluble polymers and salts].

The paper discusses the problems of purification of Provachek's rickettsias used to prepare typhus vaccines and diagnostic kits. The currently available agents contain many admixtures of rickettsias products, more commonly yolk and chick embryo yolk sack cell detritus, which make it impossible to determine the true antigenic properties of rickettsias in the context of protection and diagnosis. By applying the well-known principle of distribution of biological particles in the two-phase systems of water soluble polymers, investigations were made to examine the distribution of rickettsias and their infected biological mass in the system: polyethylene glycol-6600, sodium-500 dextran sulfate, potassium phosphate, sodium chloride in order to prepare agents of pure rickettsias. It has been found that rickettsias are distributed in the polymer-enriched phase, their number and the degree of purity when isolated from the infected biological mass depends on the capacity of an interphase wherein tissue detritus sorption occurs.

Animals↗
PubMed1999

Decreased prevalence of Orientia tsutsugamushi in trombiculid mites and wild rodents in the Primorye region, Far East Russia.

The isolation of Orientia tsutsugamushi was attempted from 249 rodents and approximately 14,000 trombiculid mites captured in the Primorye region, Far East Russia in 1993 and 1994, where high infection rates were recorded in both rodents and mites in the 1960s. However, no rickettsia was isolated from the samples. Low antibody titers against O. tsutsugamushi were detected in 7.1% of the rodents. These results indicate that the prevalence of O. tsutsugamushi in the Primorye region has decreased considerably in the past 30 years.

Animals↗
PubMed1994

Astrakhan fever rickettsiae: antigenic and genotypic analysis of isolates obtained from human and Rhipicephalus pumilio ticks.

Two spotted fever group rickettsia strains, A-108 and A-167, were isolated from the hemolymph of Rhipicephalus pumilio ticks collected in the Astrakhan region of Russia, which is area endemic for Astrakhan fever. These tick isolates were compared with a strain isolated from a patient suffering from Astrakhan fever and with reference spotted fever group rickettsiae strains. New tick isolates and the human strain were identical in their serologic, antigenic, and genetic characteristics by several methods: microimmunofluorescence, protein gel electrophoresis with immunoblotting, polymerase chain reaction followed by restriction endonuclease fragment length polymorphism analysis, and pulsed-field gel electrophoresis (PFGE). Astrakhan fever rickettsiae were found to be serologically and antigenically similar to Israeli spotted fever rickettsiae. Both of them probably belong to a single Rickettsia conorii pathotype complex. Only PFGE pattern analysis could clearly discriminate Astrakhan fever rickettsiae from other isolates.

Animals↗
PubMed1993

[The dynamics of the metabolic and functional activities of the immunocompetent cells in mice following immunization with different vaccines against Q fever].

It was shown that the immunization of mice by the chemical Q fever vaccine prepared with the use of the strain "Coxiella burnetii, Nine Mile", phase I did not markedly activate the oxidative metabolism of the peritoneal exudate cells and did not induce the non-specific cytotoxicity in them. However, it resulted in a significant suppression of the mitogen-induced proliferation of splenocytes on days 3-5. The immunization of mice by the combined (corpuscular/chemical) vaccine prepared with the use of the strain "Apodemus flavicollis-Luga", phase I induced a significant activation of the oxidative metabolism of the peritoneal exudate cells and the development of the nonspecific cytotoxicity in them, whereas no suppression of the mitogen-induced proliferation of splenocytes was observed. The differences are likely associated with the presence of the corpuscular component in the combined vaccine and the strain antigenic specificity.

Animals↗
PubMed1991

Ecological questions concerning rickettsiae.

The past ten years were characterized by the appearance of several "new" transmissible spotted fever group (SFG) rickettsioses, e.g. Israeli, Japanese and Astrakhan fevers. The factors responsible for their establishment probably include the introduction of chemicals from industry, agriculture and the timber industry into natural habitats. Such factors may influence the pathogenicity of these rickettsiae. In this case, in addition to the human influence, the mechanism of the circulation of the agents under natural conditions of both abiotic (climate, etc.) and biotic (flora and fauna) components may play a decisive role. The modern management of breeding domestic animals, indoor and outdoor maintenance, seasonal migrations, new animal foods, stress, etc., can be important factors affecting the biological properties of the Q fever agent. Nonpathogenic rickettsiae, rickettsia-like symbionts and other microorganisms circulating in nature may also influence the pathogenic rickettsiae. Studies on their interrelationships in hosts and vectors may markedly contribute to the understanding of the circulation of pathogenic rickettsiae in nature. Recognition of factors causing the appearance of new rickettsial agents or differences in pathogenicity of rickettsial strains is important not only for the prognosis of rickettsial diseases but also for the prognosis of other infectious diseases.

Animals↗
PubMed1991

Studies of a "new" rickettsiosis "Astrakhan" spotted fever.

The acute febrile disease with characteristic rash seen in Astrakhan region and named as "viral exanthema of unknown etiology" was proved to be a spotted fever group rickettsiosis. Serological examination of humans from endemic areas by complement fixation test revealed antibodies to R. conorii, R. akari and strains Netsvetaev and AR-74 of R. sibirica in titres from 20 to 640 in sera from ill persons. Of 429 sera from healthy persons, 5.1% were serologically positive in a titre of 20-40. The presence of spotted fever group rickettsiae was detected in 8 of 104 Rhipicephalus sanguineus ticks removed from dogs and tested by haemocyte test with Gimenez staining and indirect immunofluorescence technique. Attempts at isolation of rickettsiae in guinea pigs and cell cultures resulted in appearance of specific spotted fever group rickettsiae antibodies in guinea pigs (4 of 8 samples examined were positive) and detection of rickettsiae by immunofluorescence technique in cell cultures (in 2 of 12 samples tested).

Animals↗
PubMed1991

Mixed Rickettsia-virus infection in Dermacentor reticulatus imago.

Electron microscopic examination revealed replication and accumulation of Rickettsia sibirica in the fat body of experimentally infected Dermacentor reticulatus ticks. Rickettsia are released from the fat body cells by budding being surrounded with cytoplasm and plasmalemma of the host cell. Eukaryotic cell structures have been detected consisting of lamella layers whirled around the intact rickettsiae. In addition to rickettsia, microorganisms morphologically resembling Francisella tularensis and an orbivirus were found in tick tissues at morphological examination. The morphology of the virus and stages of its morphogenesis are described. Mixed viral and rickettsial infection has been shown to develop in the same ticks and even in the same fat body cells in a very close association.

Animals↗
PubMed1991

[The ultrastructure of the interaction of Rickettsia sibirica and R. slovaca with the cells of ixodid ticks].

The ultrastructural aspects of the interaction of R. sibirica and R. slovaca with cells of mites of the species Dermacentor reticulatus, D. marginatus and Ixodes ricinus after their parenteral infection, as well as in the organs of D. marginatus infected naturally in the environment, have been studied. Both rickettsial species have similar morphology in different organs of the vector. These rickettsiae not only multiply, their populations are also partly destroyed in phagolysosomes. The natural mixed infection of R. sibirica and orbivirus in cells of D. reticulatus is described. As shown in this study, both associates pass through the complete ontogenetic cycle of development on the level of the host body and also on the level of an individual cell.

Animals↗
PubMed1990

[Monoclonal antibodies to the species-specific and group antigens of Rickettsia prowazekii].

A number of hybridomas to different R. prowazekii determinants were obtained by the hybridization of spleen cells of BALB/c mice immunized with R. prowazekii corpuscular and soluble antigens. Some of the monoclonal antibodies (McAb) reacted with R. prowazekii thermolabile species-specific protein and did not react with R. typhi antigens (McAb of batches B4/4 and A-D3). McAb C5/2 and A3/2 reacted with the group thermostable antigen, common for R. prowazekii and R. typhi. McAb to the species-specific thermolabile antigen belonged to IgG2a. The McAb thus obtained permit the identification of R. prowazekii and R. typhi and the solution of the problem of the intragroup differentiation of rickettsiae belonging to the typhus group.

Animals↗
PubMed1990

[The surface antigens of Rickettsia prowazekii studied with monoclonal antibodies].

R. prowazekii antigens have been tested with the use of monoclonal antibodies (McAb) to different epitopes of the microorganism. As revealed in these tests, McAb B4/4 and A-3/D, active against species-specific thermolabile antigen, interact with protein having a molecular weight of 90-120 KD. McAb C5/2, active against thermostable group antigen common with that of Rickettsia typhi, interact with LPS-like antigen having a molecular weight of 30 KD. Ultrastructural immunochemical studies have revealed that both R. prowazekii antigens are located on surface structures of rickettsiae, such as the microcapsule and cell wall.

Antibodies, Monoclonal↗
PubMed1990

[The detection of Rickettsia prowazekii in the vectors of louse-born typhus Pediculus humanus by using monoclonal antibody-based preparations].

The results of this investigation indicate that preparations obtained on the basis of monoclonal antibodies have proved to be suitable for the detection of R. prowazekii antigens in the natural carrier of typhus when used in all types of the enzyme immunoassay; of these, the assay made by the capture method has been found to possess the highest sensitivity. The testing of the sensitivity limits has shown that this method known as ELISA-mu-capture, i.e. ELISA carried out with the use of antibodies to the mu chain of human immunoglobulin, is capable of detecting the antigen in a dose of 0.5-1 ng. Preparations based on monoclonal antibodies to species-specific R. prowazekii antigen permit the identification of the causative agent of typhus in its natural carrier within 24 hours.

Animals↗