Abstract: This invention relates to polynucleotides encoding Glycoprotein B from the RFHV/KSHV subfamily of gamma herpes viruses, three members of which are characterized in detail. DNA extracts were obtained from Macaque nemestrina and Macaque mulatta monkeys affected with retroperitoneal fibromatosis (RF), and human AIDS patients affected with Kaposi's sarcoma (KS). The extracts were amplified using consensus-degenerate oligonucleotide probes designed from known protein and DNA sequences of gamma herpes viruses. The nucleotide sequences of a 319 base pair fragment are about 76% identical between RFHV1 and KSHV, and about 60-63% identical with the closest related gamma herpes viruses outside the RFHV/KSHV subfamily. Protein sequences encoded within these fragments are are about 91% identical between RFHV1 and KSHV, and <.about.65% identical to that of other gamma herpes viruses.