Differential expression of stress proteins in virulent and attenuated promastigotes of Leishmania donovani.

Induction of stress proteins in response to heat shock and/or pH shock was compared in virulent and attenuated promastigotes of Leishmania donovani. The virulent strain showed increased expression of heat shock proteins (HSPs) of 110, 83, 70, 65, 40 and 12 kDa on heat shock (37 degrees C), while the attenuated form showed increased expression of HSPs 83, 70 and 65 only. In response to a low pH (4.5), the virulent promastigotes showed a significantly greater increase in the relative synthesis of HSP83 and HSP 70 as compared to the attenuated promastigotes. A combination of heat shock and pH shock led to an increase in the synthesis of HSP 83 and HSP 70 in the virulent parasites, while the attenuated strain showed marked increase in HSP 70 only. These results point to an important role of HSPs in the differentiation and/or virulence of L. donovani.