Protection afforded by anti-hemolysin against V. cholerae El Tor infection in experimental cholera.

Specific antisera to V. cholerae El Tor hemolysin were prepared. The sera exhibited the following characteristics: formed a single precipitin band in immunoelectrophoresis against the crude preparation of hemolysin, had no passive hemagglutinating antibodies against V. cholerae LPS sensitized cells, possessed neutralizing property to the homologous hemolysin, and afforded some small degree of protection to oral challenge of V. cholerae El Tor in experimental animals.