title: Onchocerca volvulus: expression and immunolocalization of a nematode cathepsin D-like lysosomal aspartic protease.
abstract: The N-terminal region of the cathepsin D-like aspartic protease from the human filarial parasite Onchocerca volvulus was expressed as His-tag fusion protein. Light and electron microscopic immunohistology using antibodies against the recombinant protein showed labeling of lysosomes in the hypodermis and epithelia of the intestine and the reproductive organs of Onchocerca. While developing oocytes were negative, mature oocytes and early morulae showed strong labeling. In older embryos and mature microfilariae, stained lysosomes were only found in a few cells. Cell death in degenerating microfilariae of patients untreated and treated with microfilaricidal drugs was associated with strong expression of aspartic protease. IgG1, IgG4, and IgE antibodies reactive with the recombinant protein were demonstrated in sera from onchocerciasis patients indicating exposure and recognition of the enzyme by the host's defence system. The aspartic protease of O. volvulus appears to function in intestinal digestion and tissue degradation of the filaria.
authors.affiliation: Tropical Medicine Section, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse, 74, 20359 Hamburg, Germany.
authors.forename: Abbas
authors.initials: A
authors.lastname: Jolodar
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.forename: Dietrich W
authors.initials: DW
authors.lastname: Büttner
authors.forename: David J
authors.initials: DJ
authors.lastname: Miller
authors.forename: Christel
authors.initials: C
authors.lastname: Schmetz
authors.forename: Norbert W
authors.initials: NW
authors.lastname: Brattig
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood / Q000276:immunology; D000918:Antibody Specificity; D016282:Aspartic Acid Endopeptidases / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007150:Immunohistochemistry; D008842:Microfilariae / Q000201:enzymology; D016253:Microscopy, Immunoelectron; D017181:Onchocerca volvulus / Q000201:enzymology* / Q000235:genetics / Q000276:immunology / Q000648:ultrastructure; D009855:Onchocerciasis / Q000276:immunology / Q000469:parasitology; D016133:Polymerase Chain Reaction; D011817:Rabbits
chemical_list: D000909:Antibodies, Helminth; D007106:Immune Sera; D016282:Aspartic Acid Endopeptidases