The Immunogenicity Of Glycoprotein E DNA Vaccine Against Varicella-Zoster Virus

The Varicella-Zoster virus (VZV) genome is a linear double stranded molecule and approximately 125 kb pairs in size. Sixty-nine unique open reading frames (ORFs) have been identified within the VZV genome. VZV encodes at least six groups of glycoproteins with molecular weights ranging from 20x103 to 118 x103, named VZV gE, gB, gH, gl, gC and gL. Glycoprotein E (gE) is the product of VZV ORF 68 and the primary translation product of 73 ×103 is processed to the mature glycosylated form of 88xl03-98xl03. gE is the most abundant VZV glycoprotein on the surface of virus infected cells. VZV gE induces both neutralizing antibodies and T helper cell responses and contains epitopes recognized by CD4+ and CD8+ cells.Varicella-zoster virus manifests as chickenpox (varicella) and shingles (zoster) caused by primary and reactivated infection, respectively, mfection with varicella is of particular concern in neonates, adults and immunocom-promised patients, while zoster is frequently associated with postherpetic neuralgia.Currently, the only vaccine available is a live attenuated form (Oka strain), which can become latent and cause recurrent infection. As a result, efforts to develop alternative vaccines are underway. DNA based immunization has provided protection against viral, bacterial and parasitic diseases in experimental systems and offers numerous advantages over conventional protein based preparations.Our work has focused on the construction and characterization of a plasmid containing the VZV gE gene and evaluating its antigenicity using nucleic acid immunization technology. We obtained DNA encoding VZV glycoprotein E by using PCR; the prokaryotic plasmid encoding VZV glycoprotein E was constructed (named pGEX-VZVgE). Recombinant VZV glycoprotein E was purified and identified. We also construct eukaryon plasmid encoding VZV glycoprotein E (pcDNA-VZVgE), the eukaryon plasmid was transferred into cultured COS7 cells. The expression products were determined by means of immunohistochemistry. Then, the two plasmids (pcDNA-VZVgE and the control pcDNA3.1) were injected into BALB/c mice intramuscularly.Immunogenicity and protective immunity were detected after immunization. All mice injected pcDNA-VZVgE elicited higher antibody titres than that for mice injected pcDNA3.1. Lymphocytes obtained from the spleen of pcDNA-VZVgE immunized mice exhibited higher lymphocyte proliferative response cytotoxic activity than that for pcDNA3.1 immunized mice. The protective efficacy was also higher for pcDNA-VZVgE immunized mice than that for pcDNA3.1 immunized mice. In conclusion, these results provided a new method for improving the efficacy of DNA vaccine against varicella and zoster.