| abstract |
A bacterial vaccine against Salmonella fevers, typhoid and paratyphoid fevers is obtained by fermentation, extraction and purification, vaccinating membrane antigens being extracted by putting the bacterial residue, obtained by centrifuging, in contact with a solvent of the tris (hydroxyalkyl) aminoalkane class, with stirring, at lowered temperature, pH adjusted between 8.4 and 8.6 for a period of at least some 60 hours, then, separated by decanting, followed by purifying the antigens and fractionating by ultrafiltration, and then freeze-drying the vaccinating antigen fraction. Such vaccinating antigen fraction has a molecular weight greater than 50,000, preferably 300,000, and is used to vaccinate humans and animals. |