Interactions of bovine viral diarrhoea virus glycoprotein E-rns with cell surface glycosaminoglycans

Recombinant E-rns glycoprotein of bovine viral diarrhoea virus (BVDV) has b een tagged with a marker epitope or linked to an immunoglobulin Fc tail and expressed in insect and mammalian cell lines. The product was shown to be functional, both having ribonuclease activity and binding to a variety of c ells that were permissive and non-permissive for replication of BVDV. Addit ion of soluble E-rns to the medium blocked replication of BVDV in permissiv e cells. Binding of epitope-tagged E-rns to permissive calf testes (CTe) ce lls was abolished and virus infection was reduced when cells were treated w ith heparinases I or III. E-rns failed to bind to mutant Chinese hamster ov ary (CHO) cells that lacked glycosaminoglycans (pgsA-745 cells) or heparan sulphate (pgsD-677 cells) but bound to normal CHO cells. E-rns also bound t o heparin immobilized on agarose and could be eluted by heparin and by a hi gh concentration of salt. Flow cytometric analysis of E-rns binding to CTe cell cultures showed that glycosaminoglycans such as heparin, fucoidan and dermatan sulphate all inhibit binding but dextran sulphate, keratan sulphat e, chondroitin sulphate and mannan fail to inhibit binding. The low molecul ar mass polysulphonated inhibitor suramin also inhibited binding to CTe cel ls but poly-L-lysine did not. Furthermore, suramin, the suramin analogue CP D14, fucoidan and pentosan polysulphate inhibited the infectivity of virus. It is proposed that binding of E-rns to cells is through an interaction wi th glycosaminoglycans and that BVDV may bind to cells initially through thi s interaction.