Studies on Cross-Reactivity between M. tuberculosis AOYAMA B and C. equi Ko-85

Abstract

Previously, it was repoted that a definite cross-reaction was observed in the serological reaction between M. tuberculosis (AOYAMA) and C. diphtheriae (P.W. 8).
In order to obtain further evidence for the existence of cross-reacting antigen between M. tuberculosis (AOYAMA B) and C. equi (Ko-85), experiments were carrid out by means of passive hemagglutination, conditioned hemolysis, Ouchterlony technique, and skin test with fractions TA₂ and CP, which were Presumed to be protein in nature, as antigens. Fraction TA₂ was prepared from old tuberculin, and fraction CP from C. equi (Ko-85) by a similar technique.
The absorption test was performed with anti-M. tuberculosis and anti-C. equi rabbit sera with results similar to those reported previously.
The Ouchterlony double diffution technique was carried out with anti-M. tuberculosis and anti-C. equi rabbit sera and with fractions TA₂ and CP as antigens. It gave rise to a clear reaction of identity in each case. Guinea pigs immunized with cells of M. tuberculosis or C. equi showed a clear cross-reaction in the Arthus reaction induced by bacterial antigen. These results may indicate the presence of antigens causing a cross-reaction between fractions TA₂ and CP.