We show that a cellular virus receptor functions in the envelope of a virus, allowing selective infection of cells displaying the receptor ligand. A G-deficient rabies virus (RV) pseudotyped with CD4- and CXCR4-derived proteins selectively infected cells expressing HIV-1 envelope protein. Envelope protein or CD4 antibodies blocked virus entry. Pseudotype virus formation was most efficient with chimeric receptor proteins possessing the cytoplasmic tail of the RV G spike protein (CXCR4-RV and CD4-RV). While CXCR4-RV was incorporated when expressed alone, CD4-RV incorporation required CXCR4-RV as a carrier protein, indicating a mechanism by which oligomeric surface proteins are sorted into the RV envelope. Viral vectors bearing virus receptors in their envelope may be useful reagents for targeting virus-infected cells in vivo.