Dr. Burbelo and colleagues have developed a technique for rapidly and quantitatively detecting antibody responses in sera to a variety of pathogens using recombinant proteins. We would like to apply this technique to develop an assay for detecting antibodies to HHV-8 (KSHV, the etiologic agents of Kaposi's sarcoma, an AIDS-defining condition). We initially plan to examine samples from patients with Kaposi's sarcoma, since all those patients are almost certainly infected with HHV-8. We are thus using samples from patients with previously diagnosed Kaposi's sarcoma. The samples in question are stored at the NCI FCRF repository operated by SAIC Frederick or in Rockville, MD.