ON THE NATURE OF GENETIC RESISTANCE TO TUBERCULOSIS IN THE LIGHT OF THE HOST-PARASITE RELATIONSHIPS IN NATIVELY RESISTANT AND SUSCEPTIBLE RABBITS

Abstract

These workers have found that the virulence of the individual cells of tubercle bacilli of human origin from an aerosol of H37Rv which penetrates the lungs of natively resistant and susceptible rabbits was not a significant factor in the genesis of the number of primary pulmonary tubercles which was characteristic for each race. The bacillary population changed in the lungs of rabbits after quantitative inhalation of H37Rv; these changes resembled those of bacteria growing in an artificial medium. There was a lag phase in bacillary accumulation, a period of logarithmic growth, and one of decline. The lung of the resistant rabbit is a poorer medium for the proliferation of the bacilli than the lung of a susceptible animal. The greater initial inhibition of growth in the resistant animal was due to inherent nonspecific constitutional factors rather than to a more rapid development of acquired resistance. It was found that many of the tubercle bacilli that reach the lungs of the rabbits remained alive for a considerable time without either dying or proliferating. The tubercle bacilli were transported from the primary pulmonary foci to the draining nodes in greater numbers in the resistant than in the susceptible rabbits.