Primer pairs have been developed that allow the detection and discrimination of HIV-1 and HIV-2 by PCR. When used singly, these primers and probes permit detection of between 1-10 copies of viral DNA. Greater than 90% sensitivity was seen in clinical samples for the HIV-2 primers and sensitivity was greater in samples from persons with CD4 counts less than 700. These primers can also be used in a co- amplification format with good sensitivity. These primers have been used to study the presence of HIV and related viruses in diseases of unknown etiology such as Idiopathic CD4+ T-Lymphocytopenia and Kaposi's Sarcoma. A sensitive method for amplification of RNA in the presence of UNG was developed. By this method, all steps of the PCR procedure are performed in a single tube a minimizing carryover contamination. A procedure for amplification of HIV DNA and RNA is being developed for in situ amplification and detection by PCR. This procedure is being modified for non-isotopic detection systems. These detection methods are being used to detect and quantitate virus in saliva and plasma and in infected cells from patients.