Onchocerca volvulus: expression and immunolocalization of a nematode cathepsin D-like lysosomal aspartic protease

Exp Parasitol. Jul-Aug 2004;107(3-4):145-56. doi: 10.1016/j.exppara.2004.06.006.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Helminth / blood
  • Antibodies, Helminth / immunology
  • Antibody Specificity
  • Aspartic Acid Endopeptidases / analysis
  • Aspartic Acid Endopeptidases / biosynthesis*
  • Aspartic Acid Endopeptidases / genetics
  • Aspartic Acid Endopeptidases / immunology
  • Female
  • Gene Expression Regulation, Enzymologic
  • Humans
  • Immune Sera / immunology
  • Immunohistochemistry
  • Microfilariae / enzymology
  • Microscopy, Immunoelectron
  • Onchocerca volvulus / enzymology*
  • Onchocerca volvulus / genetics
  • Onchocerca volvulus / immunology
  • Onchocerca volvulus / ultrastructure
  • Onchocerciasis / immunology
  • Onchocerciasis / parasitology
  • Polymerase Chain Reaction
  • Rabbits

Substances

  • Antibodies, Helminth
  • Immune Sera
  • Aspartic Acid Endopeptidases