DEVELOPMENTALLY-REGULATED ZINC METALLOPROTEINASES FROM 3RD-STAGE AND 4TH-STAGE LARVAE OF THE OVINE NEMATODE HAEMONCHUS-CONTORTUS

Parasitic third-stage larvae of the sheep abomasal nematode Haemonchus contortus develop and molt in vitro to the fourth stage (L4) in 48-72 hr, at which time they begin feeding. Coincident with the third molt, larvae begin to secrete significant amounts of protein into culture f luids, including a zinc metalloproteinase. This culture-derived zinc m etalloproteinase differs from a previously described metalloproteinase from infective third-stage larvae (L3[2M]), which mediates the ecdysi s process. These differences include time of expression, molecular mas s, and substrate specificity. The purified proteinase, from cultures o f L4, has a molecular weight of approximately 46 kDa, functions as an endopeptidase, and digests several native proteins of host origin incl uding fibrinogen and fibronectin.