Isolation and characterization of a toxic intracellular protein from Vibrio parahaemolyticus.

A toxic factor released from disrupted cells of Vibrio parahaemolyticus was partially purified by gel filtration after precipitation with (NH4)2SO4 at 40% saturation. The factor, which was a thermostable protein of 63 kDa, lysed human erythrocytes at a concentration of 0.15 μg ml(-1). Its LD50 by intravenous injection into mice was 6.4 μg. Fluid accumulated in suckling mice force-fed with the toxic material (1 to 25 μg). Haemolytic activity, which occurred maximall at 37°C and pH 7.0 was enhanced by Ca(2+), Cu(2+) and Zn(2+), each at 1 mM. Anti-toxic-factor serum agglutinated V. parahaemolyticus cells. The factor may play a role in the pathogenesis of V. parahaemolyticus infections and in the host's defence mechanisms against infection by the microorganism.