[摘　　要]：

A method for separating a component from a mixture of antigens is described. The component, which may be a virus or subfraction of a virus, is isolated by driving the mixture by electrophoresis through a gel containing precipitating antibodies directed against the unwanted components. The method is illustrated by the isolation of hepatitis B antigen from whole serum and by the separation of wild cucumber mosaic virus from a strain of tobacco mosaic virus.