A cell surface glycoprotein virus inhibitor that is not interferon

The possible relationship between a newly isolated glycoprotein virus inhibitor and interferon was assessed. Comparisons of the cell surface glycopeptide, obtained from mouse cerebral cortex, and interferon included antiviral activity, radioimmune assays, and the ability of antibodies raised against the brain cell surface glycoprotein (BCSG) and against mouse L cell interferon to precipitate the biological activity. BCSG was able to inhibit virus replication but only in a transient fashion. Although anti-BCSG precipitated a major portion of the radiolabelled inhibitor in a double antibody assay, anti-mouse interferon did not. Over 90% of the inhibitory activity was removed with anti-BCSG and $\text{Staphylococcus}$ protein A while anti-mouse interferon removed little, or none, of the activity under similar reaction conditions. Other properties of the BCSG that distinguish it from interferon are presented.