THE ANTIGENIC RELATIONSHIP BETWEEN BACILLUS PROTEUS X-19 AND RICKETTSIAE

Abstract

When crude extracts, obtained from Proteus X-19 are submitted to fractional precipitation by alcohol, 2 active substances, both giving polysaccharide reactions, were obtained, which proved to be immunologically different. The 1st precipitate, after addition of 2 to 4 volumes of alcohol, contains the so-called "X factor" responsible for the cross reactions between Proteus X-19 and Rickettsia. This factor has the property of being stable when heated in an alkaline reaction. The 2nd precipitate, which is obtained after the addition of an excess of alcohol, contains substances which react only with Proteus X-19 anti-serum. This substance, the so-called "P factor," is rapidly destroyed by heat in an alkaline reaction. Absorption of antityphus serum, or typhus convalescent serum, by each of these 2 substances proves that the P factor has no effect on the sera, while the X factor removes the property of producing the Weil-Felix reaction.