IONIC FACTORS REGULATING THE INTERACTION OF GARDNERELLA-VAGINALIS HEMOLYSIN WITH RED-BLOOD-CELLS

We have studied the hemolytic properties of an exotoxin released by Ga rdnerella vaginalis (Gvh). We found that hemolysis induced by Gvh is m odulated by the composition of the isotonic buffer in which the red ce lls are suspended. In particular, low pH enhances its lytic activity, whereas low ionic strength and divalent cations diminish it. The inhib itory effects of reduced salt concentration and divalent cations occur despite normal binding of the toxin to the cells. This suggests that some post-binding step is impaired. The toxin is also able to damage c holesterol-containing lipid vesicles, and even on these model membrane s it is more active at low pH. From this point of view, Gvh has some s imilarity to Clostridium perfringens B-toxin, a membrane-damaging toxi n belonging to the family of 'thiol-activated' cytolysins produced by Gram-positive bacteria.