Immunogenicity of a recombinant varicella-zoster virus gE–IE63 fusion protein, a putative vaccine candidate against primary infection and zoster reactivation

Abstract

The varicella-zoster virus (VZV) envelope glycoprotein E (gE) and immediate early protein 63 (IE63) are well known targets for specific humoral and cell-mediated immune responses during VZV infection and latency, respectively. The present study evaluated the immunogenicity of an engineered chimeric recombinant gE–IE63 (recgE–IE63) protein secreted from CHO cells, wherein a soluble form of gE, deleted of its anchor and cytoplasmic domains was fused to IE63. Guinea pig vaccinations with adjuvanted recgE–IE63 elicited a strong and specific humoral immune response directed to each counterpart. Sera from recgE–IE63-immunized animals neutralized cell-free VZV. This neutralizing capacity was dependent only on the recgE moiety as serum depletions on recgE-immobilized sepharose totally abolished VZV neutralization. The cell-mediated immune response induced by recgE–IE63 was evaluated in lymphoproliferation assays. An antigen-specific proliferative response was demonstrated after lymphocyte stimulation with recIE63 but not with recgE. We conclude that recombinant chimeric recgE–IE63 induced both humoral and cell-mediated immune responses and thus could constitute a putative subunit vaccine candidate against VZV primary infection and zoster reactivation.