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Biomedical subjects

A F Bobkov

Publications and source records attributed to A F Bobkov.

62 records · Page 4Linked to original sources
PubMedDate not supplied

[Biological and physicochemical properties of Corynebacterium diphtheriae B (Freeman) phages phi 984 and phi 9].

A scheme for preparative isolation of corynephages and their DNA is described. Study of host specificity, toxigenicity, and of cytotoxic effect induced by the phages BF, phi 9, and phi 984 has shown that phage BF has tox- phenotype, and phages phi 9 and phi 984, tox+ phenotype. These phages differ in host specificity and plaque morphology. Electron-microscopic examination of virions showed similarity of phages BF and phi 984 structures, whereas phage phi 9 was markedly different in the size of its head and tail.

Animals↗
PubMedDate not supplied

[Expression of the gene for the gp46 surface glycoprotein from the human T-cell leukemia virus type I (HTLV-I) in bacteria].

A set of recombinant plasmids containing different fragments of HTLV-I env gene has been constructed on the basis of pUR290-pUR292 vectors. The hybrid proteins containing different fragments of ENV predecessor in the C-terminal of beta-galactosidase differed in stability in Escherichia coli cells. The presence of N-terminal of ENV predecessor in recombinant proteins considerably decreases their resistance to proteases of the bacterial cell. Elimination of this fragment led to obtaining of the recombinant plasmid pESG coding for the high level of synthesis of the env-specific hybrid polypeptide (up to 30% of the total cellular protein). This 134 Kda protein is able to interact efficiently with the HTLV-I positive sera and may be used in the diagnostic test-systems for identification of the HTLV-I infected patients.

Cloning, Molecular↗
PubMedDate not supplied

[Expression of the gag-precursor of the human T-cell leukemia virus type I in Escherichia coli: study of the stability and antigenic properties of virus-specific hybrid proteins].

A set of recombinant plasmids containing sequences of HTLV-I viral gag-gene has been constructed on the basis of pUR290-pUR292 vector plasmids. The resulting hybrid proteins containing different fragments of GAG-precursor in the C-end of beta-galactosidase differed to a large extent in stability in Escherichia coli cells. The presence of an N-end fragment of GAG-precursor in the recombinants decreases drastically their resistance to bacterial proteases. Elimination of the fragment resulted in obtaining the recombinant plasmid pGdN coding for high rate synthesis (up to 30% of total cellular protein) of gag-specific hybrid polypeptide in Escherichia coli HB101 cells. This 145 kDa protein efficiently interacts with HTLV-I positive sera. It can be used in diagnostic test-systems for indicating HTLV-I infected persons.

Base Sequence↗
PubMedDate not supplied

[Genotyping and phylogenetic analysis of HIV-1 isolates circulating in Russia].

HIV-1 genetic subtypes were analyzed by the heteroduplex mobility assay (HMA) in 125 samples derived in 1995-1996 from residents of the European part of Russia. The results indicate the prevalence of six subtypes (A, B, C, D, G, and H) in the Russian Federation, with four types (A, B, C, and G) predominating (95%). The viruses belonging to subtypes A, B, and C spread via heterosexual contacts, subtype B mainly through homosexual intercourse. The majority of subtype G isolates are epidemiologically linked with previously reported nosocomial infection of children and their mothers with HIV-1 in Southern Russia. Nucleotide sequence analysis of env encoded region confirmed the results of HMA.

Genotype↗
PubMedDate not supplied

[Comparative analysis of distribution of mutant alleles of the gene coding for the CCR-5 chemokine receptor, among people in Russia, infected and not infected with HIV-1].

Comparative analysis of the distribution of deletion mutations of CC-chemokine receptor 5 (CCR-5) gene among HIV-1 infected and not infected subjects in Russia showed the incidence of the heterozygous genotype to be 17.8% among both HIV-infected and seronegative subjects. The incidence of the homozygous genotype for the deletion among seronegative individuals was 0.6%, but no homozygotes were found among HIV-1 infected patients. Study of the incidence of the mutant CCR-5 allele among patients infected with different HIV-1 subtypes showed that the susceptibility of heterozygotes to HIV-1 infection was not associated with any special genetic subtype.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

[Phenotypic and genetic analysis of a variant of human immunodeficiency virus (HIV-1) subtype B, isolated in Russia].

Human immunodeficiency type 1 virus env subtype B 95RU25B isolated from a Russian citizen is studied. The time course of clinical changes and immunological parameters over 5.5 years is presented. Phenotypical characteristics of the isolate were assessed by culturing in different sensitive cell cultures. Genotyping by the heteroduplex analysis and env gene sequencing were carried out. 95RU25B variant is capable of infecting a wide spectrum of cell cultures and by the type of replication can be classified with the S/L.3 group. The phenotypical properties of the isolate apparently determine the characteristic features in the primary structure of V3 loop.

Adolescent↗
PubMedDate not supplied

[Presence of HTLV-I antibodies in patients with sexually transmitted diseases].

The prevalence of human T-lymphotropic type I virus (HTLV-I) among patients with sexually-transmitted diseases is studied in Russia. Primary screening of antibodies to HTLV-I in the sera was carried out by enzyme immunoassay with recombinant gag and env HTLV-I-specific antigens synthesized in Escherichia coli. For secondary screening, Serodia HTLV-I and Vironostika Microelisa System kits were used. None of the 1271 serum samples collected in the towns of Perm and Ekaterinburg was HTLV-I-positive. This indicates a lower, in comparison with other European countries, level of infection with this virus, at least in this region of Russia. Testing of sera from 79 HIV-infected patients revealed none infected with HTLV-I.

HTLV-I Antibodies↗