An evaluation of different methods for labelling the surface of the filarial nematode Brugia pahangi with 125iodine.

The specificity of a range of 125I labelling techniques (Chloramine T, Iodogen, Bolton and Hunter reagent, lactoperoxidase and iodosulfanilic acid) to the surface of the filarial nematode Brugia pahangi was evaluated by autoradiography of sections of labelled worms and of dried SDS-polyacrylamide gels following electrophoresis of homogenised worm extracts. It was concluded that Bolton and Hunter reagent was not surface specific but labelled proteins throughout the body of the worm. At the light microscope level autoradiography of worms labelled using Chloramine T, Iodogen, lactoperoxidase and iodosulfanilic acid demonstrated that the 125I labelling was restricted to the worm surface. Electrophoresis and autoradiography showed that each method produced a different pattern of labelled polypeptide. A polypeptide of molecular weight 30 kDa was labelled using each method except Bolton and Hunter reagent, and appears to be a major surface component.