Micropolyspora faeni antigens of three commercial extracts.

The protein composition of three commercial extracts of Micropolyspora faeni, produced in U.S.A., England and Italy has been evaluated by agarose gel electrophoresis. By crossed immunoelectrophoresis, 'tandem'-crossed immunoelectrophoresis and by a modification of this last technique, the antigenic composition and the common antigens of the extracts have been investigated. Hyperimmune rabbit serum and a pool of five human sera with precipitins to Micropolyspora faeni have been used as source of antibody. Different quantity and quality of protein content was observed in the available batches. Different antigenic composition was also observed, not directly related to the different proteins contained therein; three antigens were definitely common to all extracts and two of them represented the major antigens of each extract. Despite the total protein content, the major and common antigens were found in similar concentrations in all three products examined. Therefore, the discrepancies observed in the precipitin reactions using the three commercial Micropolyspora faeni extracts are due to differences in the minor antigen composition of the extracts.