FRACTIONATION ON CROSS-LINKED DEXTRAN, SEPHADEX G-25, OF SERA FROM SHEEP INFECTED WITH JOHNE'S BACILLI. PRELIMINARY REPORT.

Ten sera collected during the winter months from six sheep infected with Johne's bacilli were fractionated on Sephadex G-25 columns, and all fractions tested for complement-fixing antibody, anticomplementary properties and for supplementing and inhibitory activities when added to complement-fixation tests of a heterologous antigen-antibody system: bovine or ovine antiserum with Brucella abortus antigen. Serum from a normal sheep was similarly fractionated and examined. The complement-fixing activity with a carbohydrate fraction of Johne's bacilli was confined principally to supernatant fractions of the earlier eluates containing the greater part of the serum proteins. Some of the unheated earlier and later fractions displayed a limited degree of supplementing effect. Inhibitory activity was demonstrated by certain of the earlier and later eluates after they had been heated, particularly those of antisera with initially low complement-fixing antibody titer.