This project will test for the presence of five viral antibodies in adult and juvenile Macacas on Cayo Santiago, Puerto Rico. There have been no new Macacas introduced into this colony since 1938 at which time testing indicated the presence of antibody in the colony to SV 40, herpes, measles and CMV. The fifth antigen, simian retrovirus D, was added this year. The objective will be to see if at this time this closed colony has lost antibody to the four previously studied antigens and would, therefore, provide an animal population useful for the testing of related strains of viruses. If this colony is shown to be negative for simian retrovirus, it would be very useful in the study of simian AIDS. To date four of the five troups of monkeys on Cayo Santiago have been trapped and bled. The remaining troup will be trapped, bled and all serological analysis completed by late 1986, at which point statistical analysis of the data will begin.