[Host range of influenza viruses and their receptor binding specificities]

Host-range of influenza viruses are established by many factors in nature such as the quantitative, qualitative aspects of the viral receptor, the permissive and non permissive states of host-cell condition, and also the antibody and inhibitor pressure present in the host. Influenza virus hemagglutinin recognizes specific sialyl-sugar chains of the host cell membranes. In this paper, the structure and function of sialyl-sugar chains as influenza virus receptors are described in relation to the variation of influenza viruses and the molecular evolution of influenza virus hemagglutinin.