In vitro production of choleragen and vascular permeability factor by Vibrio cholerae.

The in vitro production of significant amounts of extracellular choleragen and vascular permeability factor (PF) by Vibrio cholerae strain VC-12 (Ogawa) in a basal peptone medium required forced aeration, low incubation temperature, and a low initial pH. Filtrates of alkaline peptone cultures of VC-12 grown at 37 C contained an ion translocase inhibitory activity but neither choleragen nor PF activity, Sterile filtrates of pH 6.5 peptone cultures of VC-12 grown at 29 C contained no ion translocase inhibitory activity but possessed choleragen activity (lethality for the suckling rabbit) and PF activity to the extent that the intradermal inoculation of 0.1 ml of a 1:12,288 dilution of such a filtrate gave rise to a vascular permeability reaction (8 by 8 mm in diameter) in the guinea pig. PF excretion occurred during the late logarithmic phase of growth but did not appear to be the consequence of cell lysis. The PF activities of strains VC-12 and 569B (Inaba) were neutralized to the same extent by anticholeragen antiserum prepared against crude 569B choleragen.