A method in which the recognition specificity of a virus for a receptor
sugar chain can be easily determined with a simple instrument or
apparatus is provided. In a method for determining the recognition
specificity of a virus for a receptor sugar chain or for determining the
change in a host infected in accordance with the mutation of virus
comprising, a sample of the virus is brought into contact with a support
having a polymer with sialo-oligosaccharide immobilized on the surface
thereof; and the degree of binding therein is assayed to determine the
recognition specificity of said virus for said receptor sugar chain and
to determine the change in a host range. The method is suitable for the
surveillance of virus.