Two heat-induced proteins are associated with transformation of Schistosoma mansoni cercariae to schistosomula.

Infection with Schistosoma mansoni, a parasitic fluke, is acquired when cercariae found in freshwater bodies at ambient temperature penetrate human skin. In this study the response of S. mansoni cercariae to change in temperature from ambient to that of mammalian hosts was compared to the response of other stages that do not experience such dramatic temperature shifts. In cercariae, temperature increases from 23 degrees C to either 37 degrees C or 42 degrees C primarily induced the synthesis of two proteins unique to this stage, of Mr 60,000 and 58,000. Neither protein could be induced by similar treatment in the other two stages of the parasite found in mammalian hosts. Instead, these stages predominantly synthesized a Mr 70,000 protein that crossreacted with monoclonal and polyclonal antibodies against the Mr 70,000 heat shock protein of Drosophila and chicken. No crossreactive material was detected in cercariae, suggesting that a protein homologous to the highly conserved heat shock protein of Mr 70,000 is absent or induced to very low levels by temperature increase at this stage. The induction of the Mr 60,000 and 58,000 proteins was confined to the initial 3-hr period during cercarial transformation to the schistosomula stage.