Soluble haemagglutinin of classical vibrios: isolation and protection against cholera by its antibodies.

Soluble haemagglutinin was isolated from a late culture supernatant of classical Vibrio cholerae grown in casein-peptone broth with aeration by saturated ammonium sulphate precipitation in the cold, followed by gel filtration, electrophoresis, ether extraction and electrophoresis respectively. The antigen was found to consist of three protein fractions with different electrophoretic mobilities. Antibodies to these fractions afforded low but significant protection against oral challenges with homologous classical V. cholerae in the infant mouse cholera model.