Project 4

HUMAN IMMUNOLOGICAL RESPONSES

TO CHIMERIC L1/L2-E2-E7 VLP

Description

High risk genotype Human Papillomavirus (HPV), most frequently genotype 16, is the primary etiologic agent of cervical cancer and a common infection. Thus our overall goal is to develop a prophylactic vaccine that both prevents HPV16 infection and eliminates pre-existing or breakthrough infections. Immunization with virus-like particles (VLP) comprising only the major capsid protein L1 induces high titer neutralizing IgG that protects animals from experimental challenge. However L1 VLP vaccination does not clear pre-existing papillomavirus infection in animal models, most likely because L1 is not expressed in infected basal epithelia. Therefore, chimeric VLP (cVLP) comprising L1 and minor structural protein L2 fused with non-structural, early viral proteins, E2 and E7 have been developed. In pre-clinical studies, immunization with cVLP induces both neutralizing antibody and HPV-specific tumor immunity. These data suggest that cVLP may represent a more effective vaccine than L1 VLP, by acting both to prevent new infection and clear pre-existing infection. Thus Phase I/II clinical trials of cVLP will be performed at Hopkins. Protective antibody must neutralize HPV at the genital mucosa. However, the menstrual cycle dramatically influences transudation of IgG to the mucosa. Hypothesis I: Patients vaccinated with chimeric VLP generate neutralizing antibodies at cervical mucosa, but the titers vary significantly across the menstrual cycle due to changes in transudation. Specific aim 1: Collect serum and cervical secretions across the menstrual cycle of cVLP vaccines and determine neutralizing titers and antibody on rate. Pre-clinical studies suggest that vaccination with E2 or E7 but not L1/L2 VLP can induce papilloma regression, and demonstrate E7-specific CD8+ T lymphocyte-mediated regression of a model tumor induced by cVLP vaccination . Hypothesis II: Vaccination with L1/L2-E2-E7 cVLP induces E7-specific CD8+ cytotoxic T-lymphocytes. Specific Aim 2: Assay the E7-specific CD8+ T-lymphocytes in the peripheral blood of HLA-A2 restricted patients vaccinated with cVLP. Hypothesis III: Vaccination with L1/L2-E2-E7 cVLP induces E2-specific CD8+ cytotoxic T-lymphocytes. Specific Aim 3: Assay the E2-specific CD8+ T-lymphocytes in the peripheral blood of HLA-A2 restricted patients vaccinated with cVLP.