THE POLIOVIRUS RECEPTOR - IDENTIFICATION OF DOMAINS AND AMINO-ACID-RESIDUES CRITICAL FOR VIRUS BINDING

The N-terminal domain 1 of the human poliovirus receptor (hPVR), a thr ee-domain, immunoglobulin-like molecule, was previously shown to be ne cessary and sufficient to confer poliovirus (PV) susceptibility to mou se cells. However, studies with truncated versions of hPVR suggested t hat the C-terminal hPVR domains may contribute to receptor function. W e describe sets of hybrid receptors, constructed between hPVR and hlCA M-1 (human intercellular adhesion molecule-1) that were tested in mous e cells for hPVR functionality. Whereas the context in which hPVR is e xpressed is of minor importance, all three domains of hPVR are require d to reach wild-type function. Single and multiple amino acid exchange s were introduced into the first hPVR domain in order to localize regi ons that were involved in virus-receptor interaction. The mutations we re analyzed for their ability to bind PV1 (Mahoney) or monoclonal anti bodies as well as their ability to support viral replication in either the hPVR alpha or hybrid hPVR-hlCAM-1 receptor context. When placed i nto a model of the V domain of hPVR, the effect of the mutations indic ated that the C'C''D as well as the DE region harbored amino acids tha t contacted the PV1(M) surface in the process of receptor-virus comple x formation. The binding of the virus to the receptor and subsequent u ptake into the cells were linked; no hPVR mutants were observed that b ound the virus but blocked infection. N-glycosylation of the four site s in domains 1 and 2 is not required for hPVR function, but glycosylat ion in domain 1 has a greater effect on receptor function than that of domain 2. (C) 1994 Academic Press, Inc.