FACTORS INFLUENCING THE IN-VITRO GROWTH OF MYCOBACTERIUM-LEPRAE - EFFECT OF INOCULUM

Factors responsible for the in vitro growth of Mycobacterium leprae in Dhople-Hanks (DH) medium, and also to improve the technique devised e arlier, and the source of the M. leprae used as inoculum, were investi gated. M. leprae were obtained from armadillos and nude mice, both ino culated earlier with human- or armadillo-derived M. leprae. The growth of M. leprae in DH medium was monitored using two biochemical indicat ors. Normal growth was obtained when inocula were from livers and sple ens of M, leprae-infected armadillos. The M. leprae harvested from the footpads of nude mice failed to multiply in the same medium. Using in ocula from livers and spleens of infected armadillos, a gradual decrea se in inoculum size resulted in a proportionately slower multiplicatio n of M. leprae. When the DH medium was supplemented with whole M. lepr ae, or cell-free extracts of M. leprae, from irradiated livers and spl eens of infected armadillos, nude mouse-derived;M. leprae exhibited gr owth in the DH medium in accord with that obtained using armadillo-der ived M. leprae. Similar results were obtained with cell-free extracts of M. leprae harvested,from non-irradiated livers and spleens of infec ted armadillos, but no growth was obtained when the medium was supplem ented with extracts from livers or spleens of normal armadillos. These results indicate the possible existence of a growth factor in armadil lo-derived M. leprae.