Abstract: Polypeptide sequences for PERV-A receptors found on primate cells, including human, and the polynucleotides encoding those polypeptide receptor sequences are disclosed along with processes for using the PERV-A receptors in both in vitro and in vivo screening assays and models for agents that block viral infection. Also disclosed are processes for detecting the presence of PERV receptors in a tissue, blocking virus binding to receptors and protection of an animal, such as a human patient, from PERV infection. Antibodies that react with PERV receptors, vectors comprising the polynucleotides encoding such receptors and recombinant cells that express these receptors are also described.