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A V Timofeev

Publications and source records attributed to A V Timofeev.

49 records · Page 3Linked to original sources
PubMed1981

[Effect of a single dose of hydroxyurea on cell division in the esophageal and lingual epithelium of mice].

The mitotic index (MI), labeling index (LI) and the rate of 3H-thymidine nuclear incorporation (TNI) were revealed to decrease within the first hours after a single injection of hydroxyurea (HU) in doses of 100, 250 or 500 Mg/kg bw. After 9-12 hours the LI and MI exceeded the control level, while the TNI returned to normal. The degree of changes in the cell kinetics was found to depend on the dose of HU. The effect of HU on the proliferating cells proves, as a rule, to be temporary and reversible.

Animals↗
PubMed1979

[Cell population kinetics and the cell population mechanisms of the circadian rhythm of proliferative activity in mouse esophageal epithelium].

The dynamics of 3H-thymidine labeled mitosis and diurnal rhythm of proliferative activity was studied. The isotope was injected to BALB/C mice at the peak of diurnal rhythm of DNA synthesis activity of basal layer cells of oesophageus epithelium. It has been established that the increase in the mitotic index during 24 hours depends on the increase in number of cells being in S-period. The data show that the increase of mitotic index at diurnal rhythm occurs at the expense of 75% of new G0-cells which entered into the mitotic cycle, and of 25% of re-entering cells that had divided during the maximal mitotic activity a day before. It is found that the duration of mitotic cycle of cell population which entered into the mitotic cycle synchronously is almost equal to the period of diurnal rhythm of mitotic activity, i.e. 24 hours.

Animals↗
PubMedDate not supplied

[Synthesis, immunogenicity and antigenic characteristics of the glycoprotein E fragments from the tick-borne encephalitis virus].

Six peptide fragments of the envelope protein E of the tick-borne encephalitis virus involving the predicted T-helper epitopes were synthesized. Their ability to induce antibodies without conjugation with any high-molecular-mass carrier was studied in mice of three lines. Five of six synthesized peptides exhibited immunogenic properties, which differed in dependence on the haplotype of immunized mice. The peptide binding to the antiviral antibodies was studied, and two peptides were revealed that demonstrated a high ability to recognize the viral antibodies in the horse and human sera. These peptides are promising for the development of diagnostic agents for the tick-borne encephalitis virus.

Amino Acid Sequence↗
PubMedDate not supplied

[Protective effect of a new antiviral preparation of phosprenyl in experimental tick-borne encephalitis].

Antiviral activity of phosprenyl was studied in BALB/c mice infected with tick-borne encephalitis (TBE) virus. Up to 60% animals infected with TBE virus survived after 1-3 intramuscular injections of phosprenyl. The mortality in the untreated group infected with the virus was 100%. Direct antiviral effect of phosprenyl was studied in sensitive SPEV cells infected with TBE virus. The titer of the virus decreased 10-fold in the cells treated with the drug vs. untreated control cells. Phosprenyl stimulates some interleukins: gamma-interferon, tumor necrosis factor-alpha, and interleukin-6. The stimulating effect of the drug manifests in intact animals and in those infected with TBE virus and treated with phosprenyl. The prospects of further trials of the drug as a therapeutic and prophylactic agent in TBE are discussed.

Animals↗
PubMedDate not supplied

[Protective activity of a bacterial plasmid, bearing the gene for the tick-borne encephalitis virus NS1 nonstructural protein].

Three intramuscular injections (50 micrograms each) with bacterial plasmid pMV45 carrying nonstructural gene of NS1 protein of tick-borne encephalitis (TBE) virus protected 88% Balb/c mice from lethal challenge with the virus. Antibodies to NS1 nonstructural protein were detected in the sera of vaccinated mice after the challenge. Absence of antibodies to E structural protein indicated absence of manifest infectious process in mice vaccinated with plasmid and challenged with a lethal dose of TBE virus.

Animals↗
PubMedDate not supplied

[The process of the pH-dependent fusion of the tick-borne encephalitis virus with artificial membranes].

Fusion of TBE virus with liposomes was distinctly determined at pH 7.0 or lower, the maximum degree of fusion being observed at pH 6.4. Disorders in the native structure of TBE virus envelope protein E prevented virus-membrane fusion. Pre-incubation of viral preparations at pH 6.0 completely inhibited the fusion process, while rupture of disulfide bonds in protein E reduced the degree of fusion approximately 2-fold. Reduction of TBE virus infectivity upon changes in the native conformation of protein E as a consequence of disorders in the process of fusion of virions with cell membranes is discussed.

Encephalitis Viruses, Tick-Borne↗
PubMedDate not supplied

[The purification of tick-borne encephalitis virus preparations of cellular DNA].

According to the WHO requirements, the concentration of cellular DNA in vaccine preparations produced by pooling virus from continuous cell lines is limited to 100 ng/dose. In this study, different methods were used for purification of tick-borne encephalitis virus suspensions grown in continuous cultures of cell line 4647 from cellular DNA. Two approaches are proposed based on treatment with DNAse and promamin sulfate which allow one to reduce cellular DNA concentration in the virus preparation to the acceptable level. Prospects of their use in vaccine production are discussed.

Animals↗
PubMedDate not supplied

[Changes in biological properties of tick-borne encephalitis virus during cleavage of disulfide bonds in protein E].

The study showed the disruption of disulphide bonds in E protein of tick-borne encephalitis virus (TBE) to lead to the loss of antigenicity, infectivity, hemagglutinating and protective activities. The loss of infectivity under the effect of a thiolic reagent appears to be associated with block of the very first stage of virus-cell interaction, virus adsorption on the target cell. An attempt to reestablish the E protein structure and the above-mentioned virus properties after the removal of the thiolic reagent failed. The role of tertiary structure of E protein in the manifestation of TBE virus main biological properties is discussed.

Animals↗
PubMedDate not supplied

[DNA-topoisomerases of animal cells].

The properties and functions of the DNA topoisomerases are reviewed on the basis of the literature and the author's own data. The techniques of isolation and characterization of the covalent complexes of the topoisomerases with DNA are described.

Animals↗
PubMedDate not supplied

[A recombinant adenovirus expressing the NS1 nonstructural protein of tick-borne encephalitis virus: some characteristics of the immunologic basis of antiviral action].

Recombinant adenovirus expressing NS1 nonstructural protein of trick-borne encephalitis (TBE) virus (Rad 51) protected mice from many strains of TBE and Omsk hemorhagic fever (OHF) viruses, but virtually did not protect them from Negishi virus. During combined use of whole-virion inactivated TBE vaccine and Rad 51 the recombinant adenovirus notably potentiated the protective effect of the traditional vaccine. The results of adaptive transfer of immunological material from mice infected with Rad 51 showed that both the vaccinated animals' sera and the pool of T and B cells partially protected the recipient mice from lethal TBE infection. NS1 protein expressed by adenovirus increased the level of the key interleukins (IL) interferon, tumor necrosis factor, IL-1 beta, IL-2, and, probably, IL-4. Vaccination of mice with Rad 51 resulted in the appearance of antibodies to NS1 protein in rather high titers. The prospects of using Rad 51 as a vaccine against TBE are discussed.

Adenoviridae↗
PubMedDate not supplied

[Comparative analysis of tests on in vitro and in vivo quantitative assessment of the immunogenicity of tick-borne encephalitis vaccine].

Many-year routine use of EIA as an in vitro test demonstrated it as a highly reproducible and technological test for assessing the efficacy of vaccine against tick-borne encephalitis and its semiproducts at the intermediate stages of vaccine production. The reproducibility of mouse protection test is notably inferior to that of EIA.

Animals↗