PROTEINASES RELEASED IN-VITRO BY THE PARASITIC STAGES OF TELADORSAGIA-CIRCUMCINCTA, AN OVINE ABOMASAL NEMATODE

Proteinases released during in vitro maintenance of third (L3) and fou rth larval stage (L4) and adult Teladorsagia circumcincta (formerly Os tertagia circumcincta), an ovine abomasal nematode parasite, were char acterized on the basis of pH optima, molecular size and specific prote inase inhibitor sensitivity. Enzyme activity was maximal at alkaline p H and stage-specific release was demonstrated. Proteinases released by the adult parasite degraded a variety of protein substrates including plasminogen, albumin and haemoglobin, in a pH-dependent manner. At al kaline pH fibrinogen degradation was restricted to the alpha and beta peptide chains although the gamma peptide chain was also degraded at a cidic pH. Inhibitor sensitivity studies indicated that degradation was predominantly due to metalloproteinases although aspartyl proteinase activity was indicated at acidic pH.