Leishmanial differentiation in vitro: induction of heat shock proteins.

During temperature-induced in vitro differentiation from the promastigote to the amastigote form of the parasitic protozoan Leishmania mexicana, seven actively synthesized proteins were identified. These proteins corresponded precisely in molecular weight to the well-known heat shock proteins seen in species such as Drosophila. The minimal DNA synthesis observed in the differentiating parasites indicated that little cell division occurs during this process. The absence of RNA synthesis during early temperature-induced differentiation suggests that the leishmanial heat shock proteins are post-transcriptionally regulated. Heat shock proteins may play an adaptive role in the transition of Leishmania from arthropod to mammalian host.