Onchocerca volvulus: microfilariae secrete elastinolytic and males nonelastinolytic matrix-degrading serine and metalloproteases.

Host tissue penetration by parasitic nematodes may be mediated by both mechanical processes and proteolytic enzymes released by the parasites. Analysis of excretory-secretory (ES) products of Onchocerca volvulus microfilariae and adult stages on substrate gels demonstrated that they contain several distinct proteolytic enzymes. The analysis of the ES products of the microfilariae revealed one low and two high molecular weight proteolytic bands that degraded gelatin in substrate gels. The low molecular weight protein was found to be an elastinolytic protease cleaving soluble and insoluble elastin. ES products of males contained several high molecular weight proteases in the range of >/= 100-kDa degrading gelatin but lacked the low elastinolytic protease. The ES proteases of both developmental stages degraded the extracellular matrix proteins fibronectin, laminin, and collagen type IV, but not intact immunoglobulin G. The optimal protease activity for each of the proteases was found to be at a neutral pH. Inhibitor studies demonstrated their classification as serine and metalloproteases. Female and male extracts were able to hydrolyze azocasein but not gelatin in substrate gels. Protease activity could not be detected in ES products of females and microfilariae extract.