The nature of the virus receptors of red cells; evidence on the chemical nature of the virus receptors of red cells and of the existence of a closely analogous substance in normal serum.

THE INFLUENZA VIRUS RECEPTORS OF FOWL RED CELLS AND THE INFLUENZA VIRUS INHIBITOR OF NORMAL RABBIT SERUM HAVE THE FOLLOWING ATTRIBUTES IN COMMON: They are stable at high temperatures and in solutions of pH as high as 10.0. They both resist destruction by a number of oxidizing agents but are readily destroyed by sodium periodate, trypsin, and influenza virus. These facts suggest that the red cell receptor and the normal serum inhibitor are either the same or analogous substances and that they may belong to the mucoprotein class of compounds.