A fifteen-amino-acid TVB peptide serves as a minimal soluble receptor for subgroup B avian leukosis and sarcoma viruses.

The TVB receptor for subgroup B, D, and E avian sarcoma and leukosis viruses (ASLVs) is a tumor necrosis factor receptor-related protein that is most closely related to the TRAIL receptors. Here we show that the major subgroup B viral interaction determinants of TVB are contained within a linear 15-amino-acid peptide derived from the N-terminal region of the receptor. Moreover, this peptide was sufficient not only for binding to ASLV-B but also for activating viral entry into mammalian cells that lacked the cognate viral receptor. Peptide-dependent viral entry was blocked in the presence of bafilomycin A1, indicating that virions can be trafficked to an acidic endosomal fusion compartment without the need for physical attachment of the viral receptor to a cellular membrane.