Cross-protective antigens of Neisseria meningitidis obtained from Slaterus group Y.

An extraction of the cells of Neisseria meningitidis serogroup Y with an aqueous solution of calcium choride (0.9 m) has been shown to solubilize a number of antigens. By immunodiffusion, this mixture of antigens has been shown to react with its group-specific antiserum and also to cross-react with a number of other group-specific antisera. The cross-reacting antigen appears to be an antigen common to a number of other serogroups of meningococci, and there is some evidence that it is protein in nature. It has been demonstrated further that the calcium chloride extract contains a strong cross-protective antigen, as shown by its ability to provide good, active immunity in mice to both the homologous and heterologous serogroups of meningococci.