POLIOVIRUS RECEPTOR AND INTERACTIONS WITH POLIOVIRUS

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Molecular parameters of the interaction between the human receptor for poliovirus (hPVR), a 80 kD Ig-like, cell-surface glycoprotein with a general domain structure V-C2-C2, and the poliovirion will e studied. This will involve specific changes of hPVR polypeptide by site-directed mutagenesis, and genetic analyses of viral mutants. Receptor variants will be expressed in mouse cells for functional studies. In addition, receptor variants will be over-expressed in CHO cells to produce large quantities of purified protein suitable for crystallization and X-ray analysis, and for cryoelectron microscopic studies of the receptor/virus complex. These structural studies will be a collaboration with M.G. Rossmann. An enigma in research of poliovirus infection of animals is the apparent widespread expression of receptor mRNA and polypeptides contrasted with a limited set of target tissues. To identify genetic elements responsible for expression, the promoter of the hPVR gene will be dissected and studied in tissue culture cell with the objective to isolate cis-acting sequences and trans-acting factors. Moreover, expression regulated by the hPVR promoter will be studied by germline transformation of mice and the gene for lacZ linked to different segments of the hPVR gene promoter. To determine possible interactions of hPVR with intracellular proteins via the cytoplasmic domains, a genetic screen employing the two-hybrid system in yeast will be employed. These studies will include possible interactions between hPVR and the lymphocyte homing receptor CD44. Finally, the genetic determinants of mouse neurovirulence of PV1(LS-a), a strain of poliovirus, will be studied with attention to genomic sequences outside the coding sequence for the capsid protein.