The measles virus hemagglutinin downregulates the cellular receptor SLAM (CD150)

Signaling lymphocyte activation molecule (SLAM), a cellular receptor for measles virus, was downregulated from the surface of cells infected with either the Edmonston or wild-type KA strain of measles virus. Transfection of the expression plasmid encoding the Edmonston or KA hemagglutinin, but not the fusion protein, induced downregulation of SLAM in not only cells expressing the envelope protein on the surface, but those not expressing it. After cocultivation with cells expressing the hemagglutinin, SLAM-expressing cells also exhibited downregulation of SLAM. Thus, the measles virus hemagglutinin can induce downregulation of SLAM in cells either expressing or coming in contact with it.