DESIGN OF HEPATITIS E VIRUS GENOTYPE 1 RECOMBINANT CAPSID PROTEIN: CLONING, EXPRESSION, PURIFICATION, EVALUATION OF THE ANTIGENIC PROPERTIES

[Line immunoassay for detection of IgG antibodies to hepatitis E virus (Hepeviridae, Orthohepevirus, Orthohepevirus A)]

INTRODUCTION

The diagnostic efficacy of methods for hepatitis E serodiagnostic varies over a wide range; therefore, the combined use of tests of various formats is recommended. The aim of the research was to develop a test system for the detection of IgG antibodies to hepatitis E virus (HEV) in human serum by linear immunoassay (LIA).

MATERIAL AND METHODS

Serum samples from patients with hepatitis and healthy individuals were tested using commercial enzyme-linked immunosorbent assay systems for the presence of IgG antibodies to viral agents causing hepatitis and other infections associated with liver pathology. Recombinant antigens ORF2 and ORF3 of HEV genotypes 1 and 3 were used. The "RecomLine HEV IgG/IgM" reagent kit (Mikrogen GmbH, Germany) was used as a comparison test system.

RESULTS

The first Russian diagnostic kit "Blot-HEV", designed to detect IgG antibodies to individual HEV proteins in human serum using LIA, was developed. The antigenic base is represented by strips of a nitrocellulose membrane with immobilized recombinant antigens ORF2 (aa 406-660) and ORF3 (aa 1-113) of HEV genotypes 1 and 3, and control antigens in the form of discrete lines. The conjugate was mouse monoclonal antibodies to human class G immunoglobulins labeled with horseradish peroxidase. The chromogen solution contained the 3,3',5,5'-tetramethylbenzidine. A visual and digital recording of results was provided. The analytical sensitivity of the test kit was 0.625 IU/ml for ORF2 antigens and 2.5 IU/ml for ORF3 antigens. The absence of the influence of endogenous interfering substances on the results of the analysis and the absence of cross-reactions with antibodies to hepatitis pathogens of the other etiologies had been shown. The sensitivity of the test system compared to the "RecomLine HEV IgG/IgM" kit was 92%, specificity 97%. Shelf life in condition of storage was determined to be 12 months.

CONCLUSIONS

The developed test can be used to confirm the results of ELISA in laboratory diagnosis of hepatitis E.

DEVELOPMENT OF HEPATITIS E 3 GENOTYPE RECOMBINANT PROTEIN CAPSID OF: CLONING, EXPRESSION, PURIFICATION, EVALUATION OF THE ANTIGENIC PROPERTIES

Aim. The development of the hepatitis E virus (HEV) genotype 3 recombinant capsid protein.Materials and methods. E.coli strains, plasmid vectors, serological and clinical samples, ELISA reagent kits, molecular biological, bioinformatic, biotechnological, biochemical and serological methods.Results. Using viruscontaining material from pigs of Belgorod region (Russian Federation) we made E.coli strains producing recombinant capsid protein, containing C-terminal of viral ORF2 protein fragment fused to E.coli β-galactosidase. Recombinant protein ORF2 had been isolated from the bacterial inclusion bodies and purified by size exclusion chromatography. Antigenic specificity of the recombinant polypeptide was confirmed by ELISA and Western blotting with sera of hepatitis E patients and reference groups (healthy donors, patients with hepatitis A, B, C, infectious mononucleosis, cytomegalovirus infection and HIV-infected patients). Conclusion. HEV genotype 3 ORF2 recombinant antigen had been developed, and the possibility to use it in diagnostic tests had been experimentally shown.