PARTIAL CHARACTERIZATION OF PROTEOLYTIC-ENZYMES IN DIFFERENT DEVELOPMENTAL STAGES OF OSTERTAGIA-OSTERTAGI

Proteolytic enzymes present in extracts of third (L3) and fourth (L4) stage larvae and adults Of the cattle nematode Ostertagia ostertagi we re defined on the basis of pH optima and proteinase inhibitor sensitiv ity in spectrophotometric assays using azocasein and elastin-orcein as protein substrates. Evidence that different classes of proteinases ar e expressed in a stage specific manner was provided by the contrasting pH optima and inhibitor sensitivities shown by the enzymes in the dif ferent parasite stages. Stage specificity was confirmed by gelatin-sub strate analysis. In addition, proteolytic activity was sought in the e xcretory/secretory products (ES) of the LA following simple in vitro c ulture. Contrasting pH and inhibitor sensitivities as well as gelatin- substrate analysis showed that different proteinases were present in s omatic L4 extracts and L4 ES products. The secreted proteinases may be useful targets for serodiagnosis or vaccination.