To date, virus-encoded homologs of G protein-coupled receptors (GPCRs) have been discovered only in members of the poxvirus and herpesvirus families. The herpesvirus members have been more extensively characterized than the poxvirus members, but all were initially discovered by database searches of predicted open reading frame sequences deduced during DNA sequencing studies of the various viral DNA genomes. Unlike the herpesvirus examples (e.g. Kaposi's sarcoma-associated GPCR), the poxvirus GPRC homologs have not yet been analyzed for biological activity.