HUMAN PAPILLOMAVIRUS EXPRESSION AND ANTIGENICITY

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Our overall goal is to characterize the immune response to HPV infection for two distinct purposes: first, to identify serological markers that are correlated with a) HPV infection; b) protection in preventing the development or spread of anogenital cancers; or c) that are prognostic indicators of invasion or metastasis; and second, to understand the immune response to HPV to design immunotherapeutic strategies. We developed a first generation of reagents and techniques that allowed the initial identification of antibodies to a variety of HPV 6 and 16 proteins in human sera. The use of bacterially expressed fusion proteins in Western blot assays was particularly informative in studying antibodies to the E7 protein. We have also used yeast-expressed E7 in an ELISA and will continue to study responses to that tumor associated antigen. Recently we produced HPV capsids using vaccinia recombinants and have shown that the major capsid protein, L1, with or without L2, self-assembles to form capsids that are structurally identical to authentic virions. We have developed a sandwich ELISA using monoclonal antibodies to L1 to capture the capsid particles, and have detected antibodies in human sera that recognize a conformational epitope(s) on the native HPV particle. Most interestingly these antibodies correlate significantly with a history of HPV infection. An important goal will be to determine whether capsid antibodies are related to anogenital cancers. We have established collaborations to begin to examine the cell mediated immune response to HPV infection and the role of the host HLA genotype in the immune response. The goals of this funding period are to continue to examine the relationship between serological markers and the development of anogenital malignancies, and to expand our studies to look for T cell responses and to characterize the HLA type in our populations.