Purified Herpes Simplex Type 1 Glycoprotein D (gD) Genetically Fused with the Type 16 Human Papillomavirus E7 Oncoprotein Enhances Antigen-Specific CD8⁺ T Cell Responses and Confers Protective Antitumor Immunity

Abstract

Type 1 herpes virus (HSV-1) glycoprotein D (gD) enhances antigen-specific immune responses, particularly CD8(+) T cell responses, in mice immunized with DNA vaccines encoding hybrid proteins genetically fused with the target antigen at a site near the C-terminal end. These effects are attributed to the interaction of gD with the herpes virus entry mediator (HVEM) and the concomitant blockade of a coinhibitory mechanism mediated by the B- and T-lymphocyte attenuator (BTLA). However, questions concerning the requirement for endogenous synthesis of the antigen or the adjuvant/antigen fusion itself have not been addressed so far. In the present study, we investigated these points using purified recombinant gDs, genetically fused or not with type 16 papilloma virus (HPV-16) E7 oncoprotein. Soluble recombinant gDs, but not denatured forms, retained the ability to bind surface-exposed cellular receptors of HVEM-expressing U937 cells. In addition, in vivo administration of the recombinant proteins, particularly gD genetically fused with E7 (gDE7), promoted the activation of dendritic cells (DC) and antigen-specific cytotoxic CD8(+) T cells. More relevantly, mice immunized with the gDE7 protein developed complete preventive and partial therapeutic antitumor protection, as measured in mice following the implantation of TC-1 cells expressing HPV-16 oncoproteins. Collectively, these results demonstrate that the T cell adjuvant effects of the HSV-1 gD protein did not require endogenous synthesis and could be demonstrated in mice immunized with purified recombinant proteins.

Bicistronic DNA Vaccines Simultaneously Encoding HIV, HSV and HPV Antigens Promote CD8+ T Cell Responses and Protective Immunity

“…Previous results, based both on DNA vaccines and adenovirus vectors, have demonstrated that the fusion of heterologous sequences at the C-terminus of gD target the protein to the outer face of the cytoplasmic membrane where the binding to HVEM occurs, leading to the enhanced activation of CD8 + T cell responses to the heterologous antigen [13], [15], [32], [36]. Similar but less significant results have also been obtained with recombinant purified proteins [14], further suggesting that endogenous expression and membrane localization contributes to the gD-mediated CD8 + T cell adjuvant effects.…”

Herpes Simplex Virus Glycoprotein D Targets a Specific Dendritic Cell Subset and Improves the Performance of Vaccines to Human Papillomavirus-Associated Tumors

“…The gD, gDE7, and E7 recombinant proteins were expressed and purified as previously described (12). The concentration and the integrity of the antigens were routinely checked by PAGE and the molecular weights corresponded to those predicted in silico.…”

“…In this scenario, our group has developed two therapeutic vaccine strategies to control HPV-16-associated tumors based either on naked DNA (11) or on purified recombinant protein (12). Both strategies are based on the expression of a hybrid protein generated after the genetic fusion of HSV-1 gD with HPV-16 E7 oncoprotein (gDE7).…”

“…Regarding the vaccine formulation based on the purified recombinant protein, our previous observations demonstrated that repeated immunizations with the non-adjuvanted gDE7 protein conferred partial therapeutic antitumor protection to mice transplanted with tumors cells expressing the HPV-16 E6 and E7 oncoproteins (TC-1; ref. 12). The therapeutic antitumor protection mediated by vaccination was linked to the adjuvant properties of the gD protein.…”

Transcatheter Arterial Chemoembolization Treatment for Vulvar Cancer: A Case Report

“…In addition, herpes simplex virus infection may be an independent risk factor for vulvar cancer. Some studies have found that patients with vulvar cancer have a high positive rate of herpes simplex virus II in serum and genital herpes infection [7].…”