ON THE MECHANISM OF INVASION

In Paper I (1) a scheme was presented to illustrate the interplay of various enzymes in processes of invasion and defense. An enzyme was described, antinvasin I, which had been found in plasma and which, by destroying hyaluronidase, acted as an antiinvasion catalyst. In the course of t,his investigation a second enzyme was observed in the culture medium of certain bacteria and in snake venoms. This enzyme, proinvasin I, is produced by the pathogenic organism simultaneously with hyaluronidase and acts by destroying antinvasin I, the defensive enzyme in plasma. Hyaluronidase, although normally inactivated by antinvasin I, is then left intact, since it is accompanied and protected by proinvasin I in amounts sufficiently large to cause destruction of antinvasin I. It can be assumed that proinvasin I will materially enhance the invasion of bacteria and venoms because, by eliminating antinvasin I, it permits the action of hyaluronidase to proceed unhindered. In the present study the distribution of proinvasin I and its propert,ies have been investigated. The reaction of the enzyme with ant,invasin I in plasma of various species has been studied and an analytical test procedure devised for the quantitative determination of proinvasin I. The preparation of the test substances, as well as the viscometric methnd t,ha,t is used for the determination of hyaluronidase and of antinvasin I, wa.s described previously (1). The assay for proinvasin I essentially consists of measuring the amount of antinvasin I that has been inactivated by proinvasin I in the following system: