Detection of antibodies to Epstein-Barr virus with ELISA based on fusion capsid protein

Abstract

Listen

Translate article

Objective To develop enzyme-linked immunosorbent assay (ELISA) for detecting antibody to viral capsid antigen (VCA) of Epstein-Barr virus (EBV) by using fusion capsid protein of p23 and p18 as antigen and evaluate its diagnostic implication. Methods Full-length p23 (amino acids 1-162) and carboxy half of p18 (105-176) gene fragment were connected by a (Gly4Ser)3 linker using overlap extension PCR method. The prokaryotic expressed fusion protein of p23-p18 was purified by nickel-chelating sepharose resin affinity chromatography and used as the antigens for ELISA detection of IgG and IgM antibodies to VCA. Western blot was used to detect its antigenicity and specificity. The serum samples from 60 patients with infectious mononucleosis (IM), fifty-six chronic renal dysfunction patients on hemodialysis and 326 serum samples from healthy blood donors were examined for the presence of VCA-specific IgG and IgM by fusion protein ELISA and indirect immunoflurorescene assay (IFA) simultaneously. The specificity, sensitivity and accuracy of ELISA were detected. Results (1) Identification of the fusion protein : p23-p18 fusion gene was constructed correctly and expressed successfully in the prokaryotic expression vector. The fusion protein showed good reactivity with 10 cases of VCA IgM and 10 cases of IgG positive sera in Western blot, while no reactive bands were found with 8 cases of VCA IgM and IgG negative sera. (2)Clinical tests: IFA and ELISA with fusion proteins were used to detect VCA IgG and IgM in 442 serum samples listed above. As compared with IFA, the sensitivity, specificity and accuracy of the recombinant protein IgG ELISA were 97.3% (392/403), 97.4% (38/39) and 97.3% (430/442), respectively,and those of IgM ELISA were 94.2% (65/69), 99.5% (371/373 ), and 98.6% (436/442), respectively. Conclusion The ELISA based on fusion viral capsid proteins is sensitive, specific and accurate method for determining antibodies to VCA of EBV for both clinical diagnosis and epidemiology studies. Key words: Herpesvirus 4; human; Antigens; viral; Capsid proteins; Recombinant fusion proteins; Enzyme-linked immunosorbont assay