Onchocerca volvulus: immunohistochemical and immunoelectron microscopical distribution of a polyamine oxidizing enzyme.

We studied the distribution of a polyamine oxidizing enzyme (PAO) in Onchocerca volvulus and other nematode parasites by immunohistochemistry and electron microscopy with immunogold technique using a polyclonal antiserum raised against purified PAO from Ascaris suum. In adult O. volvulus the protein was localized in the outer zone and the area of the basal labyrinth of the hypodermis and occasionally in the outer zone of the uterine epithelium. Further, the fluid in the body cavity was strongly stained. No specific labelling was observed in the cuticle, muscles, epithelia of intestine, ovaries, testis and vas deferens or in sperm, oocytes and embryos. Third-stage larvae of O. volvulus in Simulium soubrense showed strong staining; the same was observed in Anisakis sp. larvae, where the inner and outer zone of the hypodermis were strongly labelled. All mature, intact and dead microfilariae in nodules, skin and lymph nodes were well stained and it was possible to show that the cytoplasm of the hypodermal cells, but not the mitochondria, nuclei or other organelles of muscle cells, was preferentially labelled by immunogold particles. Investigation of adult A. suum presented specific labelling of the hypodermis, but the basal labyrinth was more strongly marked than the outer zone.