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Two Neisseria meningitidis vaccines consisting principally of outer membrane protein (lot 138I-0) or outer membrane protein plus group C polysaccharide (lot 138I-M1) were prepared from the group C type 2 strain 138I. Lipopolysaccharide and lipid were removed by gel filtration in the presence of sodium deoxycholate. The vaccines were found to be nontoxic and nonpyrogenic in animals. They provided active protection in mice against mucin-enhanced killing by group B type 2 meningococci and induced good titers of type-specific bactericidal and hemagglutinating antibodies in rabbits. In five volunteers the vaccines were well tolerated and induced significant increases in serum bactericidal activity against both group C and group B strains. Three of five volunteers had a two- to fourfold increase in antibodies to the outer membrane proteins, but these antibodies did not appear to have bactericidal activity. The bactericidal antibodies to both group B and group C strains were directed against the capsular polysaccharides.

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Purified and crystalline type A botulinal toxin has been reported to possess hemagglutinating activity (Lamanna: Proc. Soc. Exptl. Biol. Med., 69, 332, 1948). This property has also been observed with culture supernatants from type B and E organisms, but not with the type C strains tested. The hemagglutination caused by type A material has now been studied more thoroughly and appears to be due to a component separable from the toxin. The toxicity of type A culture supernatants, though more susceptible to inactivation by heat and by formalin than is hemagglutination, is less sensitive to acid at pH values of 4, 3, and 2. Commercially available type B antitoxin is capable of neutralizing the hemagglutinating activity but not the toxicity of type A culture filtrates, partially purified, and crystalline toxin preparations. Type C antitoxin is entirely inactive. Type A antitoxin neutralizes hemagglutination and toxicity disproportionately (table 1). That the type A organism produces a type-specific toxin but not a type-specific hemagglutinin is also indicated by the neutralization by type A antitoxin of hemagglutination but not toxicity caused by culture supernatants of the type B "okra" strain of Clostridium botulinum. These results would be explicable if hemagglutination and toxicity were attributes of separate entities. Fortunately we have in the Oudin serum-agar technique a direct and definitive means of determining the minimum number of antigen-antibody systems in a preparation (Oudin: Compt. rend., 222, 115, 1946; Munoz and Becker: J. Immunol., 65, 47, 1950). The application of this technique reveals the formation of two separate bands of precipitate upon diffusion of type A toxin preparations across an interface into type A antitoxin, and only one band with type B antitoxin. A rabbit antiserum prepared against crystalline type A toxin also gives two bands with crystalline toxin. By repeated exposure to red blood cells, toxin preparations can be freed from hemagglutinating activity. Such toxin preparations yield only a single band of precipitate with type A antitoxin, and no precipitate with type B antitoxin in the Oudin technique. Concomitantly the capacity of these toxin preparations to form precipitates with normal sera at low temperatures is lost (Lamanna and Doak: J. Immunol., 59, 231, 1948). From the red cells exposed to toxin at lower temperatures and then eluted at 37 C, it is possible to isolate a protein hemagglutinin that gives one band of precipitate with both type A and type B antitoxin in the Oudin procedure, and that will form precipitates with normal serum at icebox temperatures.

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