Distribution of iodinated proteins in Dipetalonema viteae after surface labelling

Adult females of the filarial parasite Dipetalonema viteae were radiolabelled using chloroglycoluril and different concentrations of iodine with and without carrier iodide. A detailed quantitative analysis of the distribution of the labelled proteins were carried out using sodium dodecylsulfate and beta-mercaptoethanol to isolate the cuticle after different iodination periods. The highest specific activity was found in the pellet, which comprised the cuticular cortical zone with the highly insoluble epicuticle. However, 50% of the radiolabelled proteins were recovered in the extracts, which contained solubilized material from the somatic compartments and the basal and median zones of the cuticle. The data indicate that the isolation of surface-iodinated antigens of filariae is hampered by the presence of a detergent-insoluble epicuticle. Radiolabelled antigens solubilized by detergents are either proteins from internal somatic or cuticular regions or proteins adsorbed onto the epicuticle.