Mycobacterium avium Mino grows well in the lung,spleen or liver of susceptible mice,such as C57BL/6,C57BL/10,and B10 congenics.Infection with Mino inhibited the induction of delayed-type hypersensitivity(DTH)to BCG in the mouse receiving subcutaneous injection of BCG 2 weeks later.Post-infection with Mino did not affect DTH to BCG already established.Preceding infection with avirulent strains of atypical mycobacteria weakly suppressed the induction of DTH by BCG.On the other hand,Mino infection

more »

... did not affect DTH to SRBC.DTH to Mino and DTH to BCG detected by PPD-I and PPDs hardly showed cross-reactivity.These results suggest that tuberculin skin reaction after BCG vaccination could be suppressed by the infection with atypical mycobacteria in humans,especially where these bacterial infections are prevailing.