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Biomedical subjects

A N Burkov

Publications and source records attributed to A N Burkov.

17 recordsLinked to original sources
PubMed2002

Characterization of monoclonal antibodies and epitope mapping of the NS4 protein of hepatitis C virus.

Recombinant DNA containing sequences of HCV NS4 protein was expressed in Escherichia coli cells. Six hybridoma clones producing monoclonal antibodies (MAB) to recombinant NS4 protein (rNS4), aa 1677-1756, were developed. Mapping with a panel of 33 peptides and reciprocal competitive EIA have shown that MAB obtained revealed five antigen determinants, not described earlier: MAB 3F11 and 3F12-one genotype-independent epitope of NS4A (aa 1700-1707) common for genotypes 1, 2 and 3; MAB 1D11-genotype-independent epitope (aa 1713-1728) and MAB 1D3-genotype (subtype 1b)-specific epitope of NS4B (aa 1711-1731); MAB 6B11 and C1-two conformation-dependent determinants in 5-1-1 region. These data indicate that the 5-1-1 region of NS4 protein has a complex antigenic structure and contains at least eight epitopes, including five, revealed in the present work. MAB obtained recognized native viral protein in the cytoplasm of liver cells of patients with chronic hepatitis C. The positive rates of the immunostaining for NS4 antigen using MAB 6B11, 1D11 and 3F12 were 64, 59 and 50%, respectively. It was found that 6B11 MAB to a conformation-dependent epitope much more actively interacts with native NS4 than with the recombinant protein to which MAB was developed. The epitope recognized by 6B11 MAB is highly immunogenic since it induces the B-cell response in all patients investigated with identified anti-NS4 antibodies in blood serum. The MAB panel obtained in this study may become a useful tool for the diagnostic purposes, for the investigation of NS4B function and for the host-viral interactions at the cell level.

Animals↗
PubMed1992

Hepatitis C virus in the etiology of chronic hepatitis and liver cirrhosis: possibility of mixed viral infections due to parenteral transmission.

Sera obtained from 381 patients with chronic liver disease from four cities within the USSR were studied for HBV, HDV, and HCV markers of infection. Anti-HCV activity was detected in 41.2% of non-A, non-B cases. The etiological distribution of chronic hepatitis in Moscow and Dushanbe was similar with an approximate 20% prevalence for HBV, HDV, and HCV infections, whereas in Yakutsk 40% of cases were caused by HDV infections. The etiology of disease remained unrecognized in approximately 40% of patients with chronic liver disease in Moscow and Dushanbe and in 15% in Yakutsk. Anti-HCV activity was detected in 18.8% of patients with chronic HBV infections and in 8.3% of patients with chronic HDV infections. Anti-HCV activity was detected in 41% of patients without markers of HBV or HDV infections. The reasons for the observed differences in HCV prevalence among patients chronically infected with HDV are discussed.

Hepacivirus↗
PubMed1992

[The clinical picture and outcome of acute delta infection].

A total of 60 patients were observed with acute hepatitis delta defined at examination of 200 adult subjects with acute HBsAg-positive hepatitis. Moderate and severe forms of the disease occurred more frequently, lethality reached 13.3%. An unfavorable prognosis was related to a short-term prejaundice period with intoxication (high body temperature, head ache, vertigo, recurrent vomiting, IgM antibodies presence in the serum at the height of the disease). No patients achieved cure within 9 months following the discharge from hospital. The process acquired the form of long-term convalescence with transformation into chronic hepatitis delta.

Acute Disease↗
PubMedDate not supplied

[Characterization of a panel of monoclonal antibodies to hepatitis C NS3 recombinant protein ].

Recombinant protein rNS3 imitating helicase region (1356-1459 amino acid residues) of hepatitis C virus (HCV) was expressed in E. coli cells and used for BALB/c mice immunization. Seven hybrydoma clones producing monoclonal antibodies (MAbs) to rHS3 were obtained. All MAbs reacted in ELISA with NS3 protein from Murex anti-HCV Version III and in immunoblotting from RIBA 3. These MAbs detect 5 individual epitopes, 4 of which were conformational and 1 discontinuous. All MAbs could compete for rNS3 binding with serum antibodies from patients with chronic hepatitis C, which suggests that these MAbs can recognize the natural HCV NS3 protein.

Animals↗
PubMedDate not supplied

[TT (TTV) Virus].

Characterization of TT virus (TTV), the history of its discovery, taxonomy and identification are reviewed as update on the diagnostics of TTV infection with PCR. The variability of the virus and resulting difficulties in the selection of a TTV DNA fragment for amplification are described. Data on the virus prevalence, replication and persistence are given. The pathogenetic importance of TTV is discussed with the account of different concepts.

Blood-Borne Pathogens↗
PubMedDate not supplied

[Use of recombinant HBcore antigen for development of the diagnostic test-system].

The plasmid construction expressing recombinant HBc antigen (HbcAg) in Escherichia coli cells under the control of the PL promoter of phage I, was obtained. The specific activity of the antigen thus obtained was controlled by the enzyme immunoassay (EIA) method and compared with the reference system "AxSYM CORE assay" ("Abbott", USA) with four panels of sera (altogether 111 samples). The coincidence of the results of the compared test system with the reference was 96.4%, which made it possible to recommend this genetic construction of recombinant HBcAg for the production of EIA systems.

Bacteriophage lambda↗
PubMedDate not supplied

[Theoretical prediction of the antigenic epitopes of severe acute respiratory syndrome (SARS-CoV) proteins and evaluation of their diagnostic value].

Analysis of the sequence of a number of proteins of the virus causing severe acute respiratory syndrome (SARS-CoV) was used to theoretically predict antigenic epitopes. Nine sequences, encoding for the predicted epitopes in spike, nucleocapside, and membranous SARS CoV proteins, were synthesized by polymyrase chain reaction and cloned into the pGEX 4-T2 vector. The resultant plasmids were expressed in the E. coil cells and purified by glutathione-Sepharose affinity chromatography.

Amino Acid Sequence↗
PubMedDate not supplied

[Impact of the heterogenicity of amino acid sequence on the immunoreactivity of an antigenic epitopic complex localized within amino acids 1192-1456 of protein NS3 protein of hepatitis C virus].

Recombinant proteins were used to study the effect of heterogenicity of the primary structure of NS3 protein of hepatitis C (HCV) on the immunoreactivity of a complex of antigenic epitopes located within the amino acid sequences 1192-1456. Six genes encoding for the above fragment NS3 from different genotypes were collected from synthetic oligonucleotides and expressed in E. coli cells, by using the polymerase chain reaction. The homology of amino acid sequences of antigens ranged from 78.4 to 92.2%. All the antigens showed a higher coefficient of their reactivity with antibodies in the sera samples from patients infected by HCV of a respective genotype; however, there was no strong genotype-specific immunoreactivity. The findings lead to the conclusion that the primary structure of antigens has an impact on their immunoreactivity. Selection of variants of the primary structures of antigens is essential in developing a diagnostic test.

Antibody Specificity↗
PubMedDate not supplied

[Comparison of the diagnostic value of recombinant antigens and synthetic peptides that mimic the immunogenic epitopes of the envelop protein gp41 in the enzyme immunodetection of HIV-1 antibodies].

The study was undertaken to comparatively examine the efficiency of HIV antibody detection by enzyme immunoassay using recombinant antigens and synthetic peptides containing the most immunodominant region of the human immunodeficiency virus envelop protein gp41-cytotoxic T-lymphocytic (CTL) epitope. The application of the synthetic peptides that mimic this region has been to be inadequately effective. The recombinant proteins that contain the CTL epitope may be successfully used for the diagnosis of HIV-1, by using enzyme immunoassay as they show a higher sensitivity in detecting antibodies than do the synthetic peptises.

Epitopes, T-Lymphocyte↗