Our colleagues have developed a technique for rapidly and quantitatively detecting antibody responses in sera to a variety of antigens using recombinant proteins. We would like to apply this technique to develop an assay for detecting antibodies to HHV- 8 (KSHV, the etiologic agent of Kaposi s sarcoma, an AIDS-defining condition). In addition we would like to potentially measure antibody responses to HIV, other infectious agents, and human antigens, to see if antibodies (or high antibody titers) to these antigens are associated with Kaposi s sarcoma or HIV infection. We initially plan to examine samples from patients with Kaposi s sarcoma, since all those patients are almost certainly infected with HHV-8. We would subsequently plan to examine samples from HIV positive and HIV negative patients without known Kaposi s sarcoma. We are thus requesting permission to use samples from patients with and without previously diagnosed Kaposi's Sarcoma. In addition to antibody testing, we would also like to examine these samples for evidence of infection with other infectious agents, such as newly identified or unknown viruses, using techniques such as PCR or deep