β-Inhibitor, Its Biological and Physicochemical Properties with Particular Emphasis on the Differences from α-Inhibitor, Immune Serum and Properdin

Biological and physicochemical properties of the β-inhibitor was studied in order to differentiate this inhibitor from the α-inhibitor, antiviral immune serum and properdin. The substance is fairly heat-labile and susceptible to trypsin action, indicating the protein nature. However these characteristics are quite different from that of specific immune serum. The fl-inhibitor is resistant to the action of both RDE and KIO4, thus distinguishing it from the α-inhibitor. Though the adsorption to zymosan has been proved with this agent as has been already proved with properdin, the participation of complement for the action of the β-inhibitor is not necessary at all. Further, biological activity of the β-inhibitor is limited just to the mouse nonadapted type A influenza viruses. The richest source of β-inhibiror was ox serum, but it was also detected in the serum of the rabbit and mouse. The purification of the β-inhibitor was performed from ox serum and after precipitation with ammonium sulfate, adsorption to and elution from zymosan was particularly effective to remove the other entities contained in ox serum. Though the 240 times purification was achieved in the sense of HAI activity per mg. of nitrogen, the heat lability increased when the purification advanced. From this reason, the purification study is still going on.