PROTECTIVE RESPONSE IN GUINEA-PIGS EXPOSED TO MYCOBACTERIUM-AVIUM-INTRACELLULARE MYCOBACTERIUM-SCROFULACEUM, BCG AND SOUTH INDIAN ISOLATES OF MYCOBACTERIUM-TUBERCULOSIS

The protective immunity resulting from exposure to nontuberculous myco bacteria (NTM), BCG and virulent mycobacteria in different sequences w as studied in the guineapig model employing strains prevalent in the s outh Indian BCG trial area and time kinetics to observe the immuno-mod ulation. The findings suggest that during the early course of challeng e infection in guineapigs there was no interference with the immunity due to BCG, by prior exposure to NTM. In the animals sensitised with M .avium intracellulare before immunisation, the challenge infection was localised and confined to the site of inoculation, and only a few org anisms reached the spleen. However, at the later stages of the infecti on, as seen by the spleen viable counts at 12 wk, it appeared that the barrier at the localised site of infection may not be intact in the a nimals with prior exposure to NTM, and a few organisms disseminate to the spleen.