Axenic cultivation of amastigotes of Leishmania donovani and Leishmania major and their infectivity.

Two clones of promastigotes, one of Leishmania donovani and one of L. major, and an uncloned stock of L. major were axenically transformed to heat-shock amastigotes, at 35 and 37 degrees C, respectively. Of the four different culture media tested, a relatively cheap, liquid medium, RBLM, was found to be the best, both for the transformation of the promastigotes and the serial, axenic cultivation of the amastigotes. In an experiment of 30 days duration, serial cultivation, in an atmosphere with 5% CO2, was possible by subculturing every three days. There were significant differences in virulence in BALB/c mice between axenically-cultured amastigotes and promastigotes, both in terms of the weights, lengths and parasite burdens of the spleens of mice infected intraperitoneally (ip) with L. donovani or L. major and of the appearance, type and size of the cutaneous lesions which developed in mice given L. major by intradermal inoculation.