Developmentally regulated zinc metalloproteinases from third- and fourth-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 fluids, including a zinc metalloproteinase. This culture-derived zinc metalloproteinase differs from a previously described metalloproteinase from infective third-stage larvae (L3[2M]), which mediates the ecdysis process. These differences include time of expression, molecular mass, and substrate specificity. The purified proteinase, from cultures of L4, has a molecular weight of approximately 46 kDa, functions as an endopeptidase, and digests several native proteins of host origin including fibrinogen and fibronectin.