Internalization of virus binding proteins during entry of reovirus into K562 erythroleukemia cells

Virus overlay protein blot assays of cell membranes of mouse L929 fibroblasts have revealed multiple reovirus binding proteins with molecular masses ranging from approximately 26 to 200 kDa. To determine whether this observation is unique to L cells, membranes of human K562 erythroleukemia cells and human A431 epidermoid cells were subjected to virus overlay protein blot assays. The profiles of reovirus binding proteins of these cells are similar to that of L cells and reovirus is capable of binding to at least 30 membrane proteins. To determine the fate of reovirus binding proteins during viral entry into K562 cells which are infectible by reovirus, cell surface proteins were derivatized with biotin. During viral entry, biotinylated cell surface proteins with molecular masses of 55, 74, 78, 80, 90, 94, 98, and 115 kDa became internalized. The 90- and 115-kDa proteins also bound reovirus, indicating that they are likely to be reovirus receptors. Thus many virus binding proteins are present at the surface of host cells but very few are internalized during entry of reovirus. K562 cells also express glycophorin A which is the putative reovirus receptor on erythrocytes. However, during entry of reovirus into K562 cells, glycophorin A did not appear to become internalized. Reovirus could be shown to attach to erythrocytes but viral entry into these cells could not be demonstrated.