Using an organotypic culture model of the HPV18 life cycle we will investigate how E6-PDZ interactions contribute to the viral life cycle and to the initial stages of HPV-induced neoplasia. This will be done by generating mutations within the E6-PDZ binding domain, which are known to leave all of E6 s other functions intact, thereby allowing very specific questions to be addressed. This will be combined with studies to investigate the specific importance of known, and potentially newly identif ied, PDZ substrates of E6 in contributing to different aspects of the infectious cycle, with a particular emphasis being placed on understanding how these interactions help to maintain the viral episome. This is particularly relevant for understanding viral persistence and how viral integration might initiate during a normal infection, a feature that appears to play a major role in oncogenic transformation by the virus. These virological studies will be combined with cell biological analyses o f the functions of a subset of E6-PDZ substrate proteins in human keratinocytes. The main focus here will be to understand how E6 targeting of a class of proteins involved in the control of cell polarity and proliferation can directly contribute to E6 s ability to induce human malignancies.