RECEPTOR UTILIZATION BY REOVIRUS TYPE-3 - DISTINCT BINDING-SITES ON THYMOMA AND FIBROBLAST CELL-LINES RESULT IN DIFFERENTIAL COMPARTMENTALIZATION OF VIRIONS

Reovirus type 3/D infects cells following binding to specific cell-surface receptors. The characteristics of these receptors may play an important role in determining post-binding events critical to the viral life cycle. Some cell lines, i.e. L-cells, appear to bind reovirus type 3/D utilizing sialylated proteins as specific receptors for viral adsorption. Such binding results in productive infection. Other cell lines, i.e. R1.1 thymoma cells, bind reovirus type 3/D in a sialic acid independent manner which does not result in productive infection. Yet, a peptide analogue of the viral binding site is capable of inhibiting binding of reovirus type 3 to both cell types, suggesting the same viral epitope interacts with both cellular receptors. When binding of reovirus is studied by electron microscopy, the virus particles enter the L cells via coated pits, and are later seen in large accumulations in endocytic vesicles near the transGolgi network. In contrast, R1.1 cells appear to divert the reovirus particles to a cell membrane elaboration, with reovirus remaining bound to the cell membrane. At later time points with R1.1 cells, there are no apparent intracellular accumulations. These studies demonstrate that viruses can attach to different cells utilizing distinct receptors, and this may play a role in the ability of the virions to productively infect the cells. The capacity of virus to be adsorbed to cellular receptors which do not lead to internalization may be an important mechanism for the sequestration and clearance of virus. These observations have implications for the tissue tropism demonstrated by reovirus type 3/D and other viruses. © 1992.