EXPERIMENTAL VIBRIO INFECTIONS OF DEVELOPING CHICK EMBRYOS.

Developing chick embryos are highly susceptible to infection with strains on V. cholerae representing Gardner and Venkatraman's 6 groups and the types Inaba and Ogawa. There is a moderate decrease in susceptibility with advancing age of the embryo. The influence of dosage on survival rates is not marked, probably because a minimal dose, consisting of a very few organisms, is sufficient to produce death rapidly. Passive protection of a low order is conferred on the embryos by the introduction of inactivated specific immune serum at the time of inoculation of vibrios. This protective influence is enormously enhanced by the previous or simultaneous administration of guinea pig complement. The antigens of group I organisms which give rise to embryo-protective and bacteriolytic antibodies are dual in character. One antigen is shared by all members of the group and is productive of antibodies which will protect against infections with all strains of the group, of whatever type. The other antigen is type-specific, and its antibodies are protective and lytic only for organisms of the homologous type.