The effect of tunicamycin on Leishmania braziliensis cell growth, cell morphology and ultrastructure.

The effect of tunicamycin (TM) on Leishmania braziliensis promastigotes in culture has been studied. TM at different concentrations (2, 4, 6 micrograms/ml) inhibits promastigote growth as the mean generation time of control cells, 36 hr, is changed to 41, 46 and 55 hr, respectively. Cells remain viable after long exposure to 2 micrograms/ml of TM and can be cultured in the presence of the drug for several generations. Under these conditions cells tend to round up and many "ruffle"-like structures appear at the parasite cell surface. At the ultrastructural level, cell coat disappears and the rough endoplasmic reticulum appears distended. Other structures remain unaltered by the drug treatment. The changes in cell morphology are discussed in relation to changes in cell surface morphology. The possible use of these TM-transformed cells as experimental systems for host-parasite studies is also considered.