SYSTEMIC ANTIBODY-RESPONSES OF CALVES TO LOW-MOLECULAR-WEIGHT COOPERIA-ONCOPHORA ANTIGENS

The systemic antibody responses to adult Cooperia oncophora antigen we re studied using sera obtained from calves during a 6-week period foll owing a single oral infection with either 20 000 or 100 000 third-stag e C. oncophora larvae. Dose dependent increasing titres of IgG binding complete adult Cooperia antigen were found in the sera of Cooperia-in fected calves. SDS-gel electrophoresis under reducing conditions, foll owed by Western blotting, revealed that the increase of IgG binding Co operia antigens could be attributed mainly to specific binding of IgG to a complex of 12-15 kDa protein fragments of Cooperia adult antigen. This protein may represent a Cooperia oncophora-specific component th at can be used for serodiagnosis.