CHOLERA TOXINS: QUANTITATION OF THE FROG SKIN REACTION AND ITS RELATION TO EXPERIMENTAL ENTERIC TOXICITY

Characterization of surface properties of Vibrio cholerae

A number of isolates of Vibrio cholerae were examined with respect to their (i) surface hydrophobicity as measured by hydrophobic interaction chromatography, (ii) capacity to agglutinate erythrocytes, and (iii) ability to bind to an ion-exchange matrix. V. cholerae isolates, cultured under a variety of growth conditions, were conspicuously hydrophobic. The hydrophobicity was accentuated when these strains were (i) cultivated in a chemically defined synthetic medium, (ii) harvested at the exponential phase of growth, and (iii) cultured at a lower temperature. Rough strains were more hydrophobic than smooth strains. Of the various surface components examined, the outer membrane proteins were conspicuously hydrophobic. The cell-bound hemagglutinating activity of V. cholerae strains was increased when these strains were cultured in synthetic medium and harvested at the stationary phase of growth. This property was unaffected by the growth temperature. Only D-mannose, at a high concentration, inhibited hemagglutination of 80% of the isolates examined. L-Fucose did not inhibit the hemagglutinating activity. V. cholerae strains adhered strongly to the anion-exchange matrix DEAE-cellulose. The surface charge density was accentuated when these strains were grown in synthetic medium. These results suggest that the V. cholerae surface contains both specific (hemagglutinating) and nonspecific (hydrophobic and ionic) factors which may influence its eventual adherence to the host cell surface.

Intestinal absorption, exocrine pancreatic function and response to Vibrio cholerae infection in protein deficient Patas monkeys (Erythrocebus patas)

Six patas monkeys (Erythrocebus patas) were fed a protein-free diet. Sixteen animals of the same species received a standard monkey diet. The protein-depleted patas showed reduced absorption of folic acid but not D-xylose, and 5 out of 6 had a decrease in the exocrine pancreatic function. Animals with reduced folic acid absorption and pancreatic enzyme production developed a longer lasting diarrhoea and excreted the microorganisms for a longer time when challenged with Vibrio cholerae.

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.