Antigen specificity in experimental bovine tuberculosis

This report describes the kinetics of T-cell responses to a panel of mycoba cterial antigens (PPD-M, PPD-A, ESAT-6, Ag85, 38kD, MPB64, MPB70, MPB83, hs p16.1, hsp65, and hsp70) following experimental infection of cattle with My cobacterium bovis. Increased antigen-specific lymphocyte proliferation, gam ma interferon, and interleukin-2 responses were observed in all calves foll owing infection. Positive lymphocyte proliferation and cytokine responses t o PPD-M and ESAT-6 were observed throughout the infection period studied. I n contrast, responses to all other antigens were more variable and were not constantly present, suggesting that antigen cocktails rather than individu al antigens should be used for immunodiagnosis. The detection of cytokine r esponses in the absence of lymphocyte proliferation, particularly during th e early stages of infection, suggests a role for antigen-specific cytokine readout systems in the early identification of M. bovis infection in cattle .