Tumour necrosis factor-alpha induces preferential expression of stress proteins in virulent promastigotes of Leishmania donovani.

Intracellular replication of Leishmania donovani inside macrophages is essential for production of disease and development of the parasite. Tumour necrosis factor-alpha (TNF) plays an integral role in host response to Leishmania. The effect of TNF on expression of heat-shock proteins (Hsp) was examined in promastigotes of L. donovani. TNF treatment led to an increased expression of Hsp83, Hsp70 and Hsp65 in virulent, but not avirulent, parasites. In response to stress by H2O2 or sodium arsenite, an increased expression of Hsp60 was observed in the virulent, but not avirulent, parasites. The virulent promastigotes were found to be more resistant to the toxic effects of TNF and other stresses. The data indicated that Hsp expressed in response to stress encountered in macrophages may confer protection to parasites and play a crucial role in their survival in the mammalian host.