Yeast Protects Against Bacterial Infection

Since 1940 when we began a study of sensitization in laboratory animals treated with pertussis vaccine we have emphasized the role of the bacterial protein in this phenomenon. Considerable information has been accumulated which indicates that vaccination with Hemnophilus pertussis, while increasing resistance against infection by the same organism will, at the same time, produce hypersensitivity to the Hen?ophilus pertussis antigen. Such sensitivity, however, is not specific for pertussis but crosses with several other species of gram negative bacteria.1 28 Furthermore, mice immunized against pertussis are much more susceptible to infection by other gram negative bacteria than are their normal litter mates. Apparently, specific immunization can produce a non-specific lowering of resistance which predisposes the host to unrelated infections"5 and this may well be listed as another untoward effect of bacterial allergy. Because bacterial protein has been shown to play a part in hypersensitivity and, from the above observation, is implicated in the etiology of infections, the search for an appropriate protein for desensitization was undertaken. The obvious selection was protein associated with the nucleic acid of the bacterial cell from the specific Henmophilus organism. Injection of this material reinforced the resistance of sensitized animals. However, since hypersensitivity is not species specific, the possibility of another source of comparable material was apparent and it was found that a commercial preparation of yeast sodium nucleate would not only reduce the hypersensitivity of vaccinated animals to the same pertussis antigen, but would make them refractory to gram negative bacteria. This logically lead to the possibility of protection for normal animals against similar infection. Our numerous experiments prove that normal mice after injection with sodium nucleate are protected against infection by Proteus, Pasteurella, Brucella and E. coli organisms. Subsequent studies indicated that different brands of sodium nucleate were variable in potency; some were even inactive. Furthermore, the protective dosage of the active preparations ran as high as 100 mg./mouse. In search of the active principle we looked to the