This proposal focuses on the development of non-radioisotopic in situ hybridization assay to detect LAV/HTLV-III infected cells, and to develop a method for recovery of AIDS virus from infected sources using a T4+ cell line that expresses the transactivating translational gene (tat) of LAV/HTLV-III as the basis of a virus detection/culture system. The offeror emphasize that in situ hybridization offers advantages over immunologic methods of detecting virus infected cells since it is able to detect infected cells which are not expressing viral proteins. Their method for in situ hybridization uses non-isotopic detection which allows easy visualization of infected cells by standard microscopy within one working day. The objectives of the current proposal are to simplify the method so that it can be adapted for clinical use, and to improve the detection to the point where a single copy of virus DNA or RNA can be detected.