Support for a workshop on pathogenesis by non-acute retroviruses is requested. Viruses that cause cancer, immunodeficiencies, and neuropathology will be considered. Viruses to be considered include murine leukemia viruses, avian leukosis virus, feline leukemia virus, murine mammary tumor virus, HTLV-I, bovine leukemia virus, MAIDS virus, and non-human lentiviruses. These viruses provide important model systems for disease processes that are relevant to analogous human diseases. Significant progress has been made in the last year, which supports an in-depth work-shop. Projected attendance is 150 people.