The expression of small heat shock proteins in the microfilaria of Brugia pahangi and their possible role in development.

Development of the microfilariae of Brugia pahangi in the mammalian host is blocked until uptake by a mosquito vector when the developmental cycle is re-initiated. Comparison of the profile of polypeptides labelled in microfilariae cultured at mammalian temperature (37 degrees C) or mosquito temperature (28 degrees C) revealed a complex of low-molecular-weight proteins (18 kDa and 22-24 kDa) synthesized only in microfilariae at 37 degrees C. The synthesis of these proteins was also induced by transfer of microfilariae to 41 degrees C (i.e., heat shock conditions), suggesting that these are heat shock proteins. The expression of the small heat shock proteins in the Brugia life cycle is developmentally regulated, as they are not observed in the mature adult female. Their synthesis is strictly temperature dependent and is repressed upon transfer of the microfilariae to 28 degrees C.