INTERACTION BETWEEN PSEUDORABIES VIRUS AND HEPARIN HEPARAN SULFATE - PSEUDORABIES VIRUS MUTANTS DIFFER IN THEIR INTERACTION WITH HEPARIN/HEPARAN SULFATE WHEN ALTERED FOR SPECIFIC GLYCOPROTEIN-C HEPARIN-BINDINGDOMAIN/

Cell surface heparan sulfate serves as an initial receptor for a numbe r of herpesviruses including pseudorabies virus (PrV). It has been dem onstrated that the heparan sulfate-binding domain of PrV glycoprotein C is composed of three discrete clusters of basic residues correspondi ng to amino acids 76-RRKPPR-81, 96-HGRKR-100, and 133-RFYRRGRFR-141, r espectively, and that these clusters are functionally redundant, i.e. each of them could independently support PrV attachment to cells (Flyn n, S. J., and Ryan, P. (1996) J. Virol. 70, 1355-1364). To evaluate th e functional significance of each of these clusters we have used PrV m utants in which, owing to specific alterations in glycoprotein C, the heparan sulfate-binding site is dominated by a single specific cluster . These mutants exhibited different patterns of susceptibility to sele ctively N-, 2-O-, and 6-O-desulfated heparin preparations in virus att achment/infectivity assay. Moreover PrV mutants differed as regard to efficiency of their attachment to and infection of cells pretreated wi th relatively low amounts of heparan sulfate-degrading enzymes. Furthe rmore glycoprotein C species, purified from respective mutants, bound heparin oligosaccharide fragments of different minimum size. These dif ferences suggest that specific clusters of basic amino acids of the he paran sulfate-binding domain of glycoprotein C may support PrV binding to different structural features/stretches within the heparan sulfate chain.