Study on immunogenicity of B cell epitopes of Epstein-Barr virus latent membrane protein-2 / 中华传染病杂志

ABSTRACT

Objective To analyze the immunogenicity of selected B-cell epitopes of Epstein-Barr virus (EBV) latent membrane protein-2 (LMP2). Methods Three potential dominant B-cell epitopes of LMP2199-209, LMP2318-322 and LMP2381-391 from EBV LMP2 had been predicted using bioinformaties methods. The gene fragments of three epitopes were cloned respectively into pET32a(+) vector and transformed into E. coli strain BL21 (DE3). After identification by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting, the expression products were purified by Ni-NTA agarose affinity chromatography. BALB/c mice in immunized groups were immunized by multi-point intracutaneous injection with the three purified epitope proteins,respectively; and mice in control groups were injected with pET32a (+) protein or phosphate buffered saline(PBS), respectively. The sera from mice at week O, week 3 and week 6 of injection were collected for determination of epitope-specific antibody IgG by enzyme linked immunosorbent assay (ELISA) using epitope proteins as coating antigens. The ability of serum antibody recognizing nature EBV antigen was determined at week 6 of immunization. Results Three epitope proteins of LMP2199-209 ,LMP2318-322 and LMP2381-391 were successfully expressed in prokaryotic system. Epitopespecific antibodies IgG could be detected respectively in the sera of all immunized mice, and the levels of antibodies increased with immunized time increasing. The antibody levels in LMP2318-322 immunized group at week 3 and week 6 were significantly higher than that of pET32a (+) protein control group (F= 493.85 and 773.99, respectively; both P＜0. 05), and the antibody levels in LMP2381-391 immunized group at week 3 and week 6 were also significantly higher than that of pET32a (+) protein control group (F= 926.33 and 309.14, respectively; both P＜0.05). Antibody level in LMP2199-209 immunized group at week 6 was significantly higher than that of pET32a ( + ) protein control group (F=87.27, P＜0.05). The antibody IgG in serum from immunized mice with three epitope proteins could all recognize nature EBV antigens, especially LMP2199-209 and LMP2381-391 immunized groups.Conclusions Three possible dominant epitopes of LMP2199-209, LMP2318-322 and LMP2381-391 from EBV LMP2 are prepared by prokaryotic expression system and exhibit obvious immunogenicity, which could be used for further research of EBV infection and related tumor vaccine.