This project was planned to investigate the role of naturally occurring mutations in the zinc finger region of JC virus regulatory protein, T antigen. JC virus is the cause of the fatal CNS disease, progressive multifocal leukoencehpalopathy, occurring some AIDS patients. This project has been suspended due to the departure of the investigator, Dr. Chi N.(Tom)Ng. Aspects of this project will be subsumed in that of Dr. Jian C. Wang who recently joined the Neurotoxicology Section.