On the receptor of influenza viruses. 1. Artificial receptor for influenza virus.

It is only for the myxoviruses that the chemistry of the cellular receptors has been elucidated, at least to some extent. From studies with soluble glycopro­ teins which can inhibit hemagglutination, it has been shown that the receptor site is ./V-acetylneuraminic acid (NANA), which is located on the terminal position of the oligosaccharide side chains. The soluble inhibitory glycoproteins and the cellular re­ ceptors are regarded as chemical analoges, com­ peting for and serving as substrates for the neur­ aminidase of myxoviruses. Thus virus adsorption has been regarded as an enzyme-substrate linkage (for ref. see1). Recently this view has been revised, since it has been shown that myxoviruses could attach to cell surfaces even if virus neuraminidase had been inhibited by specific antibodies2> 3, or other inhibitors 4’ 5. In addition, neuraminidase-free hemagglutinin has been isolated which adsorbs to red cells 6> 7, therefore, can be assumed, that both the neuraminidase and the hemagglutinin react with the cellular receptor. Tiffany and Blough 8 recently demonstrated that fetuin-containing artificial membranes exclusively bind myxoviruses; the receptor function was lost, if NANA had been removed from the substrate. In order to elucidate further the functional significance of NANA, as the dominating compound of the myxovirus receptor, red blood cells were coated with NANA-containing glycoproteins of different structures and their virus binding capacities were tested. It was tried to define, whether neuraminidase or the hemagglutinating component of the virus surface are responsible for the attachment of in­ fluenza viruses.