More than 90% of cervical cancers have been associated with human papillomaviruses (HPVs). Two HPV oncogenic proteins, E6 and E7, are important in the induction and maintenance of cellular transformation and are co-expressed in most HPV-containing cervical cancers. Therefore, vaccines or immunotherapies targeting E6 and E7 proteins will provide an opportunity to prevent and treat HPV-associated cervical malignancies. The destruction of tumor cells will most likely require induction of a tumor specific cytotoxic T lymphocyte (CTL) response as well as potentially a tumor specific T helper (Th) response. Studies in vitro indicate that T cell responses as well as potentially a tumor specific T helper (Th) response. Studies in vitro indicate that T cell responses vary qualitatively and quantitatively depending on two parameter: 1) the density of peptide-MHC complexes on the surface of antigen presenting cells, and 2) the nature of co-stimulatory signals delivered to the T cell in conjunction with T cell receptor engagement. Based on this improved understanding, we have identified potential strategies to optimize T cell activation by modifying both parameters in vivo. These strategies will utilize a vaccinia vector and E7 as the targeted tumor specific antigen. We will initially use E7 as the targeted tumor specific antigen because E7 is well characterized and is more abundant than E6. The broad objective of this proposal is to develop strategies to enhance E7 specific T cell responses by optimizing the activation of E7-specific T cells and to evaluate the potency of the vaccines in generating antitumor immunity against tumors expressing E6 and E7. Since the failure of the immune system to reject tumors is frequently attributed to insufficient CD4+ T help, we will focus on strategies that enhance CD4+ helper T cell responses. Specifically, we plan to (1) Construct recombinant vaccinia which increase the density of E7-peptide-MHC class II complexes by delivering E7 into the MHC class II pathway and engineer double recombinant vaccines that will enable the co-expression of E7 or Sig E7 LAMP-1 along with molecules capable of providing co-stimulatory signals to responding T cells. (2). Utilize in vivo protection and cure assays with the E7 expressing tumor to determine the most potent recombinant vaccinia and optimize parameters of vaccination. (3). Characterize the standard immunologic parameters of E7-specific responses generated by optimized recombinant vaccinia vaccines. (4) Perform head-to-head comparison of various E7vaccines in antitumor immunity using E7 expressing murine model tumors. (5) Evaluate potential synergies between different vaccine for their potency in protection and treatment of established E7 expressing murine tumors.
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