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Extracellular proteases of Onchocerca.
A Lackey1, E R James, J A Sakanari
1Department of Pathology, University of California, San Francisco 94143-0506.
Experimental Parasitology
|February 1, 1989
Summary
Onchocerca parasites secrete enzymes to aid larval migration through skin. A serine elastase from L3 larvae facilitates movement, while microfilariae also produce proteases contributing to tissue damage.
Area of Science:
- Parasitology
- Molecular Biology
- Biochemistry
Background:
- Onchocerca parasites cause significant human and animal diseases.
- Larval stages of Onchocerca undergo tissue migration, crucial for infection establishment.
- Proteolytic enzymes are hypothesized to facilitate helminth larval migration.
Purpose of the Study:
- To investigate the role of proteolytic enzymes in Onchocerca larval migration.
- To identify specific proteases secreted by different Onchocerca life stages.
- To compare protease activity between Onchocerca and a free-living nematode.
Main Methods:
- Assaying neutral protease activity against a model extracellular matrix.
- Utilizing substrate gel electrophoresis to identify secreted proteases.
- Comparing protease secretion in Onchocerca L3 larvae and microfilariae with Caenorhabditis elegans.
Main Results:
- Onchocerca lienalis L3 larvae secreted a 43-kDa serine elastase that degraded extracellular matrix.
- Microfilariae of O. cervicalis and O. cervipedis produced serine and metalloproteases at lower levels.
- No neutral protease activity was detected in free-living C. elegans or adult Onchocerca.
- Protease expression was stage-specific, with differences observed between uterine and skin microfilariae.
Conclusions:
- A serine elastase secreted by Onchocerca L3 larvae is critical for migration from the bite site.
- Microfilarial proteases, though less potent individually, may contribute to skin pathology in heavy infections.
- Protease secretion is a key parasitic strategy for Onchocerca tissue invasion and development.