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Biomedical subjects

A F Bobkov

Publications and source records attributed to A F Bobkov.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[The use of the vif gene expression product of HIV-1 in bacteria for detecting specific antibodies in the sera of infected persons].

A fragment of the genome of human immunodeficiency virus type 1 (HIV-1) coding for p23 protein, the product of vif gene, was cloned in a plasmid vector pUR291. The resulting recombinant plasmid pLacVif1 was conducive in E. coli cells to the synthesis of a hybrid polypeptide with molecular weight of 136 kDa containing antigenic determinants of p23 protein of HIV-1. The employment of this polypeptide for analysis of HIV-1-positive sera by indirect enzyme immunoassay showed that vif-specific antibodies were found in 53% of the cases and their appearance was not related to the stage of the disease.

Antibody Specificity↗
PubMedDate not supplied

[Effect of home-made narcotics on infectious activity of HIV-1].

The stability of human immunodeficiency virus, type 1 (HIV-1), strain IIIB, was studied in liquid preparations of homemade drugs. The "Vint" preparation (containing Methamphetamine and obtained from Ephedrine) as well as "Khanka" (a liquid surrogate opiate made from poppy straw) were analyzed within the case study. HIV-1/IIIB was shown to maintain its infectious activity in "Khanka" at room temperature for least 7 days. The HIV-1 activity in neutralized "Vint" did not essentially change after a 30-minute incubation at pH 7.0. While an incubation in the acid "Vint" solution entailed a more rapidly decreasing activity. However, the virus infection ability preserved during the entire time period, during which the drug was fit for injections, i.e. for 30 minutes at room temperature or for 20 hours at 4 degrees C. Therefore, the infection virus could well preserve in the "Khanka" and "Vint" solutions after its entry, with infected blood, of large volumes of the discussed drugs. The mentioned big volumes of HIV-1 contaminated drugs, shared later into ready-to-use portions, could be the cause for HIV-1 dissemination among those who practice the parenteral administration of these substances. Besides, "Khanka" was shown to have little or no effect on the virus replication to cell culture MT-4. Its presence brought about an insignificant 1.5-fold increase in the viral stock (observed on days 2 and 3 after contamination) only when 2 x 10(5) MT-4 cells per ml and HIV-1/IIIB TCID 50 0.005 were used.

Anti-HIV Agents↗
PubMedDate not supplied

[Variants of human immunodeficiency virus type 1, detected in Russia among those infected by the sexual route].

We analyzed 52 blood samples obtained independently from among individuals, who had never practiced the intravenous administration of drugs, for the purpose of detecting the subtypes of HIV-1 that circulated during 1999-2002. The study materials were analyzed by the methods of gag/env heteroduplex mobility assay and by env gp120 C2-V3 sequencing. Four viral subtypes (A,B,C and G) and a recombinant gagA/envB were detected in subjects contaminated through heterosexual contacts. Noteworthily, HIV-1 variations of subtype A, which were found in 22 (73.3%) of 30 analyzed samples, were predominant in this risk group. An analysis of nucleotide sequences exposed a high degree of homology between the viruses, detected previously among drug-addicts, and the isolates detected by us in subjects contaminated heterosexually. However, HIV-1, subtype B, detected by us in all 16 studied cases, still continue to circulate among the males infected through homosexual contacts with men.

Adolescent↗
PubMedDate not supplied

[Molecular epidemiology of HIV-infection in drug addicts of Southern Ural].

The analysis of HIV-1 variants circulating among drug addicts in 16 settlements of the Sverdlov, Chelyabinsk and Orenburg regions (72, 90 and 42 patients respectively) was carried out. As shown by the serological analysis, the spread of HIV-1 variant IDU-A among the drug addicts in this area continued in this area and could be detected in 99.5% of the samples (203 out of 204 samples). These data were confirmed by the results of the analysis of 35 samples by the Heteroduplex Mobility Assay for genes env and gag. The analysis of nucleotide sequences of gene env revealed that HIV-1 variants in the Southern Urals, where the greatest outbreak of HIV infection in Russia had been registered, were genetically related to viruses of subtype A, detected earlier in this group of risk in other regions of Russia, as well as in Ukraine, Belarus and other East European countries.

Comorbidity↗
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[The genetic variability of the protease-encoding region in HIV-1 A isolates and in CRF03_AB recombinants as observed in the CIS territory].

Protease-encoding nucleotide sequences of 27 HIV-1 variants isolated in Russia and other CIS countries from seropositive intravenous drug-users were analyzed. None of the above persons did ever take antiretroviral drugs. The nucleotide sequences were shown to belong to subtypes A and to be have a high degree of genetic homogeneity (0.00-3.23; mean--1.38 +/- 0.79). No isolates contained any primary mutations of resistance to protease inhibitors. At the same time, above one half of the isolates bore the V771 substitution, which, according to published data, is the secondary mutation of resistance that conditions a higher resistance to Nelfinavir. Moreover, the substitution was associated with 2 synonymous mutations in triplets 31 and 78, which denotes a single origin for all V771 variants.

Adolescent↗
PubMedDate not supplied

[Development of microchips for the detection of mutations of HIV-1 variability to protease inhibitors and the usage results].

An original biochip was constructed for the detection of 34 mutations of HIV-1 resistance to protease. A technology was worked out, which is based on the hybridization of a fluorescence-labeled amplified fragment of the pol gene of the HIV-1 provirus DNA with a set of specific oligonucleotides immobilized in 3-D hydrogel pads of the biological microchip. The biochip was used to analyze 115 samples of the subtype-1 provirus HIV-1 DNA isolated from untreated IDUs and their sexual partners in 15 regions of former USSR countries. Substitution of Val/IIe in position 77 of protease (V771) is known as secondary mutation of resistance to Nelfinavir detected in 55 (47.8%) of 115 HIV-1 variations. Its first appearance was registered in a patient with HIV in April 1997 in Tver, where its carrying variant caused an HIV outbreak. It is demonstrated that the V771-substitution variant, that dominates in Moscow, caused outbreaks in Irkutsk and Yekaterinburg and spread into separate districts of Perm and Perm Region. At the same time, no V771 HIV-1 was detected in any of the HIV studied cases diagnosed before 1998 in Moldova, Ukraine and Rostov Region.

Amino Acid Substitution↗
PubMedDate not supplied

[Biological properties of HIV-1 variants circulating among drug users in Russia].

Human immunodeficiency virus type 1 variants belonging to subtype A, as well as recombinant gaga/engvB variants, derived from HIV-infected patients living in the Moscow and Perm Regions, were isolated and characterized. Intravenous administration of psychoactive drugs was a major risk factor of the infection for all the patients. All the examined isolates of HIV-1 types A and A/B were shown to be characterized by a low virus-specific activity and to be used as secondary CCR5 and CXCR4 protein receptors. The findings suggest that the domination of subtype A variant in this risk group is unassociated with fundamental differences in biological properties between the isolates of this subtype and recombinant viruses.

Amino Acid Sequence↗
PubMedDate not supplied

[Anti-CD4 autoimmunity in HIV-infected persons in Russia].

The frequency of anti-CD4 antibodies was determined in the sera or plasma derived from the patients infected with HIV-1 belonging to different genetic subgroups. The anti-CD4-antibodies in a dilution of > or = 1:1000 were found in 14% of the patients infected with the gagA/envA virus characteristic for injectable drug users in East Europe. The frequency of autoimmune antibodies among the HIV-infected patients with envB virus was substantially less (4.4%). Competitive ELISA using monoclonal antibodies to different CD4 domains demonstrated that irrespective of the viral genotype, the autoimmune epitope is located within the D4 or D3/D4 domains of CD4 receptor.

Amino Acid Sequence↗
PubMedDate not supplied

[Protease and reverse transcriptase genetic polymorphism in HIV type 1 subtype A variants predominating in cis countries].

To define frequencies of drug resistance mutations among HIV-1 variants circulating within the territory of Russia, subtype A HIV-1 nucleotide sequences encoding protease and reverse transcriptase were analyzed. The analysis was carried out in 141 antiretroviral-naive individuals. Low frequency (less than 1%) of primary drug resistance mutations was shown. However, high frequencies of secondary mutations V77I in protease and A62V in RT (67% H 63%, respectively) linked to each other in most cases were observed. The HIV-1 isolates bearing both substitutions (MutV77I/A62V) were also characterized by the presence of several synonymous mutations, suggesting common origin for these viruses. HIV Biochip Hybridization microarray and/or Restriction fragment-length polymorphism analyses were performed to characterize gene pol polymorphism in additional 178 subtype A HIV-1 isolates. Among total 319 samples studied, Mutv77IA62V variant accounted for 56%, and was found to predominate in Russia in terms of both its geographical distribution and number of cases caused. Moreover, these viruses were prevalent in the regions known to have highest incidence of HIV-1 infection (Irkutsk, Samara, and Moscow regions). In addition, three other variants were found: viruses not containing the substitutions V77I or A62V, and variants bearing only one of them. Evolutional relationships between all four HIV-1 variants, as well as potential impact of the gene pol polymorphism on HIV-1 replicative fitness and drug resistance development are discussed.

Amino Acid Substitution↗
PubMedDate not supplied

[Molecular and epidemiological characterization of HIV-infection in the Altai Territory].

The genetic analysis of the variants of HIV, type 1, circulating in the Altai Territory was made. The results obtained with the use of the serological analysis and the method of the comparative evaluation of the electrophoretic mobility of heteroduplexes demonstrated that almost all analyzed samples (98.3%) belonged to subtype A. Genetic differences between these viruses did not exceed 9.20%. Moreover, 86.8% of them contained mutation V771 in the protease-coding area. Thus, HIV of subtype A, characteristic of CIS countries and containing mutation V771, may be regarded as the dominating viruses in the Altai Territory and not the viruses of subtypes B, C or A/E, typical of comparatively less remote China.

HIV Infections↗
PubMedDate not supplied

[The expression of a fragment of the HIV-1 Nef gene in Escherichia coli bacteria].

The presence of antibodies to p27, the product of gene Nef, may be an important diagnostic sign since some sera from subjects of the risk groups negative to HIV-1 structural proteins may contain antibody to p27. The study resulted in construction of a hybrid plasmid determining in E coli bacteria the synthesis of a hybrid protein the N-terminus part of which is represented by full-size beta-galactosidase and the C-terminus by a part of protein p27 with the main immunoreactive epitopes. The resulting polypeptide specifically interacts with sera of the infected subjects and may be used for detection of antibodies to the protein Nef in the blood of virus-carriers.

Epitopes↗
PubMedDate not supplied

[The expression of a fragment of the HIV-1 env gene in the cells of Escherichia coli bacteria].

A recombinant plasmid pEK6 determining the synthesis of a hybrid protein the N-terminus of which was represented by full-size beta-galactosidase and C-terminus by HIV-1 gene env virus-specific sequence was constructed. The analysis of lysates of E. coli HB101/pEK6 bacteria in 6% PAAGE revealed additional proteins with molecular weights from 185 to 130 kDa. These proteins interacted with blood serum antibodies of a virus carrier but formed no specific bands with sera from normal donors. Densitometric analysis of polyacrylamide gels stained with Coomassi R250 demonstrated that the level of production of recombinant protein was at least 15% of the total cell protein. Hybrid polypeptides formed poorly soluble inclusion bodies in the bacterial cells. Study of the immunological properties of the recombinant polypeptides showed that immunization of rabbits with these proteins induced antibodies specifically reacting with viral polypeptides with molecular weights of about 82 and 140 kDa. Such features as a high level of synthesis, technologically feasible purification of inclusion bodies, and adequate antigenic properties recommend this preparation for use in the development of diagnostic test systems.

Amino Acid Sequence↗
PubMedDate not supplied

[The properties of HIV protease synthesized in E. coli cells].

A hybrid plasmid pPR6 was constructed containing BgII-EcoRI fragment of the pol region of HIV (strain IIIB) genome which determined the synthesis of virus-specific protease. Extracts of E. coli DN5/pPR6 bacteria provided for specific hydrolysis of hybrid protein p165 (the N-terminus of which is presented by complete beta-galactosidase and the C-terminus by duplicated area of virus-specific precursor p55 containing a site for virus-specific protease located at the border of proteins p17 and p24) with formation of products having molecular weights of 19, 42, 28, 23, and 19 kD. Polypeptides 119K, 23K, and 19K are products of complete hydrolysis, and 42K a result of partial cleavage. The kinetics of hydrolysis in relation to pH values of the reaction mixture was analysed. It is suggested that the reported system of HIV protease activity determination be used for screening of potential inhibitors of this enzyme.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

[Effectiveness of Soviet derivatives of phosphonic acid and their combination with interferon inducers in cell cultures and in a model of herpetic meningoencephalitis in mice].

Nationally synthesized chemopreparations: phosphonoacetic (PAA), phosphonoformic (PFA) acids and acycloguanosine (Acg) exhibit a marked antiherpetic effect in cell cultures and marked protective effect in herpes meningoencephalitis in mice induced by intraperitoneal inoculation of herpes simplex virus type 1 (HSV-1) (43% PFA, 33% PAA, 25% Acg). Both in vitro and in vivo (mouse meningoencephalitis), PFA (its trisodium salt) on the whole proved to be less toxic than PAA but exerted a higher or similar antiherpetic effect. The combined use of pyrophosphate analogues (PAA, PFA) with Acg is more effective that their use separately both in vitro and in herpes meningoencephalitis in mice an produces an additive effect or one similar to it. Systemic inoculation of interferon inducers, lafarine or ridostine, is effective in herpes meningoencephalitis in mice induced by intraperitoneal inoculation of HSV-1 (the protective effect 33% and 26%, respectively). The combined use of ridostine and PAA in herpes meningoencephalitis in mice led to synergistic effect.

Acyclovir↗
PubMedDate not supplied

[Use of an immunoperoxidase method in situ for detecting recombinant clones of vaccinia virus containing an expressed gene of influenza viral hemagglutinins].

The vaccine L-IVP strain of vaccinia virus (VV) was used to construct the recombinant viral clones containing the influenza A hemagglutinin gene. The recombinant T plasmid was obtained with HA gene inserted in the vector pGS-20 (B. Moss) under the 7.5 K promoter of VV. A homologous recombination technique was used to insert the gene with the flanking TK sequences into vaccinia virus genome. The recombinant clones were selected by dot-hybridization with [32P]-labeled HA-probe. These recombinants were analysed for HA gene expression by the indirect immunoperoxidase method in situ using the peroxidase conjugate of the staphylococcal A-protein. This technique allows to obtain stable stained preparation and analyse the protein behavior at the ultrastructural level.

Clone Cells↗
PubMedDate not supplied

[Restriction analysis of the DNA of the toxigenic corynephages BF, phi 984, phi 9 and C].

The results of restriction analysis of toxigenic corynephages BF, phi 984, phi 9, and C are presented. Phage BF was shown to be a deletion derivative of phage beta vir, phage phi 984 to be omega-like. Toxigenic corynephages phi 9 and C belong to a new group of corynephages designated phi. DNA of phages phi 9 and C as well as chromosomal DNA of the indicator strains was not hydrolysed by specific Hind III endonuclease, that is likely to be associated with the presence of a modification system in host strains.

Bacteriophages↗