[Seroconversion to various hepatitis C virus antigens in patients with hepatitis C from various sources].

A total of 136 patients with acute icteric hepatitis C, including patients with known outcome, were examined. Therefore, 46 serological samples, obtained from 13 patients with subsequent remission, and 63 samples, obtained from 13 patients, who subsequently developed the chronic disease stage, were analyzed. The serum of known outcome patients were examined, by using the immune-enzyme analysis method, to the antibodies of both class IgG, and IgM.

[Detection of type specific antibodies to hepatitis C virus NS4 protein in hepatitis C patients by enzyme immunoassay].

A multi-enzyme immmune-assay test system was designed for serotyping of genotypes hepatitis C virus (HCV) and a method of such typing of the serum of patients with hepatitis C was worked out. The above test-system was worked out on the basis of a study of 10 type-specific peptides modeling different fragments from NS4-protein variable region of HCV. The designed test system was evaluated by using a set of 42 serum samples obtained at random from patients with chronic hepatitis C, which had been preliminarily genotyped by polymerase chain reaction.

[Test for specific antibodies to virus hepatitis delta based on synthetic peptides].

Solid-phase synthesis of three linear peptides overlapping the major immunodominant epitope of HDAg, which located within amino acid (aa) segment 53-108, and peptide aa 167-179 was carried out. The structure of the peptides corresponded to the sequences of isolates HDV type I. Their antigen reactivity was studied by indirect enzyme immunoassay with sera from patients with hepatitis D and from asymptomatic carriers of anti-delta antibodies.

[Spectrum of antibodies to HCV antigens in patients with different clinical patterns of chronic HCV infection].

Correlations between the spectra of antibodies to HCV proteins represented by various antigenic determinants and clinical variants of chronic HCV infection were studied. Synthetic peptides core-16, NS4-20, and NS5-23 simulating the immunodominant regions of the core, NS4 and NS5 proteins and recombinant proteins core-114 and NS4-86 were used as antigens. The results indicate that if the serum of an HCV patients contains no IgG to both antigenic determinants of NS4 or to NS5 in combination with any core antigenic determinant, a clinical and biochemical remission is highly probable.

[Diagnostic significance of antibody detection to various hepatitis C virus antigens in patients with acute and chronic HCV-infection].

Aim: To examine diagnostic value of antibodies to various HCV antigens in patients with acute and chronic HCV-infection.

Material And Methods: Enzyme immunoassay has tested blood sera from 136 patients with icteric acute hepatitis C (AHC) and 45 patients with chronic HCV infection for IgG antibodies to antigens of proteins core, NS4, NS5, HCV. Synthetic peptides core-16, NS4-20, NS5-23 were used as antigens.

[Determination of type-specific synthetic peptide antibodies to hepatitis delta virus ].

Nine peptides from immunodominant (53-68 and 65-80 aa) and hypervariable (201-213 aa) regions derived from delta antigen sequences corresponding to 3 HDV genotypes were synthesized. Type specificity of antibodies to the resultant peptides was evaluated by indirect enzyme immunoassay with sera from patients with hepatitis D and asymptomatic carriers of anti-delta antibodies. Analysis of the results showed that HDV circulating in the Central Volga region belongs to type I in the majority of cases.

[Type-specific antibodies to hepatitis C virus in sera from patients with various hematologic diseases].

The reactivity of 100 sera taken from patients with different blood diseases and donors with respect to synthesized peptides in the variable area of protein NS4 of hepatitis C virus was studied. The presence of type-specific antibodies in the blood sera of patients with hepatitis C was shown. Two antigenic determinant corresponding to 1683-1705 and 1711-1732 amino acid residues in the protein area under study were detected.

[Detection of antibodies to the nucleocapsid protein of Hepatitis C virus by immunoenzyme analysis using synthetic peptides of nucleocapsid N-terminal part].

Solid-phase synthesis of 7 linear peptides overlapping the immunodominant N-terminal region of hepatitis C virus (HCV) core protein (aa 7-75) was carried out. Their antigen reactivity was studied by non-competitive ELISA with sera from patients with chronic HCV infection. Three B-epitopes located within aa 7-19, 20-34, and 39-75 appeared to be the most immunoreactive.

[Serological study of hepatitis C virus NS5 protein epitopes and their clinical and diagnostic significance].

Three peptides corresponding to the 2295-2317 aa NS5 HCV region and individual parts of this region were synthesized. Antigenic properties of these peptides were investigated. The 2295-2317 aa region contains at least two epitopes of different nature.

[Antigenic specificity of recombinant polypeptides, containing fragments of hepatitis E virus proteins].

Antigenic specificity of recombinant polypeptides HE40 and HE60 containing fragments of gene ORF2 and ORF3 protein products of hepatitis E, strain Burma, produced in E. coli cells, is analyzed. Blood sera from patients with acute hepatitis from an endemic region in Uzbekistan were tested for IgG to recombinant antigens by solid-phase enzyme immunoassay with a protein fragment coded by PRF3 gene, a synthetic peptide previously characterized in a commercial test system, as the positive control.

[Antigenic activity of delta-antigen peptides corresponding to three genotypes of the delta hepatitis virus].

Six synthetic peptides from immunodominant region 65-80 aa derived from the sequences of delta-antigen corresponding to 3 HDV genotypes were obtained. Their antigenic activities were assessed by indirect enzyme immunoassay with sera of patients with hepatitis D and of asymptomatic carriers of anti-delta antibodies. Differences in antigenic characteristics of full-size 65-80 and truncated 71-80 aa peptides corresponding to three HDV genotypes were revealed.

[Use of synthetic peptides as additional antigens for detecting antibodies to hepatitis C virus].

Peptide fragments of hepatitis C virus (HCV) nonstructural protein NS4 capable of reacting with anti-HCV in enzyme immunoassay are synthesized. Addition of synthetic peptides to recombinant nucleocapsid HCV antigen absorbed on solid phase notably improves the efficacy of detection of antibodies to HCV in the sera of patients with hepatitis C.

[Analysis of the organization of immunodominant epitopes of hepatitis virus E orf2 and orf3 proteins using synthetic peptides].

A set of synthetic peptides of different length derived from proteins encoded by open reading frames (ORF) 1, 2, and 3 of hepatitis E virus (HEV) genome was synthesized and tested for antigenicity in indirect enzyme immunoassay. Peptides 414-433 (ORF2 protein) and 99-119 (ORF3) specifically react with antiHEV-positive sera collected during outbreaks in the Central Asian areas of the former USSR. The antigenic structure of the Central Asian variants and the Burmese types of HEV was found similar.

[Expression of HIV-1 epitopes included in particles formed by human hepatitis B virus nucleocapsid protein].

Hybrids of the core protein of hepatitis B virus (HBcAg) have been designed which carry N-terminal insertions of B- and T-cell epitopes of HIV-1 an immunodominant B-epitope from gp41, a T-cell epitope from p34 pol, and a cluster of B- and T-cell epitopes from p17 gag. The hybrids have been synthesized using two expression systems-one based on the thermoinducible PR promoter of bacteriophage lambda and the other one based on phi 10 promoter of bacteriophage T7 with 3-5% and 7-14% yields, respectively. The hybrids have dual HBV and HIV-1 immunospecificity and are assembled into particles similar to those formed by the protein carrier HBcAg.

[Synthesis and antigenic activity of peptides from the ORF3 protein sequence of hepatitis E virus].

The hepatitis E virus (HEV) is an infection agent (detected recently) responsible for an enterically transmitted non-A, non-B hepatitis [1,2]. Hepatitis E is a big problem in many developing countries, including the Central Asian areas of the former Soviet Union [2]. By cloning followed by sequence analysis of the HEV genome, three open reading frames (ORF) have been identified, among them ORF3 encoding a protein containing 123 amino acid residues, the function of this protein being unknown.

[Heterologous epitopes in the central part of the hepatitis B virus core protein].

A set of plasmids was constructed determining synthesis of hybrid proteins with insertions of antigenic determinants of preS1 and preS2 regions of HBV in the middle part of HBcAg. The polypeptides containing the 31-36 or monomeric 94-105 preS1 epitopes were water-soluble and formed particles similar to the 27-nm ones of native HBcAg, possessing antigenic properties of both HBcAg and the inserted epitope, while the hybrids containing 133-143 of preS2 or a trimeric form of the 94-105 preS1 epitope became membrane-bound. Another hybrid encoded by plasmid pPS2M31 contained two regions of HBcAg modification: insertion of amino acids 133-143 a.

[Introduction of heterologous epitopes at the N-terminal part of the hepatitis B core protein].

For investigation of proteins possessing assigned immunological properties, plasmids pPS31-42, pPS1-5, pPS2-17, and pPS1P-30 were constructed encoding the hepatitis B core protein (HBcAg) with N-terminally inserted immunodominant epitopes of preS regions (amino acids 31-36 or 94-105 of preS1, or 133-143 of preS2). Analysis of the hybrid proteins with the use of ELISA and immunoelectron microscopy showed that the insertions did not prevent specific aggregation of the protein molecules, the inserted sequences being exposed on the surface of the particles obtained, and both HBcAg and the corresponding preS determinants were antigenically active.

[Localization of the immunodominant site in the hepatitis B virus core antigen using synthetic peptides].

Based on theoretical analysis of secondary structure and hydrophilicity data, the region (residues 73-89) of the HBV core-antigen presumably containing the antigenic determinant has been revealed. The epitope mapping of this region with the use of synthetic peptides, obtained by the pin technology and solid phase method, was carried out. Peptides were synthesized in two variants with different amino acids residues in the position 80 (Ala, Ile).

[Synthesis and comparative analysis of antigenic activity of peptides from hypervariable region V3 of human immunodeficiency virus I gp120 surface glycoprotein].

A set of peptides (amino acid positions 10-23) corresponding to seven most widely spread variants of the gp120 V3 domain in the HIV-infected population of South Russia were prepared by the solid-phase synthesis. A laboratory variant of the indirect enzyme-linked immunosorbent assay (ELISA) was developed for the determination of V3 specific antibodies with use of the peptides synthesized. The analysis of the V3-specific antibodies in HIV-infected using the elaborated test-system revealed a correlation between the V3 variants distribution and the occurrence of antibodies against these variants.

[Expression in Escherichia coli of hepatitis B virus polymerase and its functional domains].

The plasmids have been constructed permitting expression of hepatitis B viral polymerase and its functional domains, the catalytic and end ones, as hybrid proteins containing 12 alien amino acids in the N-terminal. Immunoblotting with the rabbit antisera to N- and C-terminals of hepatitis B polymerase amino acid sequence has demonstrated that constructed plasmids determine the synthesis of the corresponding proteins in bacterial cells. HBV polymerase is processed in Escherichia coli cells.