Characterization of proteinases in different isolates of adult Haemonchus contortus

Abstract

A high degree of intra- and inter-geographical variation has been demonstrated previously in the excretory/secretory proteinases released by adult Haemonchus contortus. Proteinase activity has also been associated with host-protective 'hidden' antigens isolated from the gut of adult H. contortus. If similar geographical strain variation also exists within the gut-associated proteinases, this will have important implications for the development of a globally effective vaccine. The proteinases active in integral-membrane protein extracts from 3 different strains of adult H. contortus were characterized on the basis of their pH optima and molecular size. Although enzyme activity was detected over a wide pH range, the majority of proteinase activity was detected at acidic pH. Differences in specific activity and size of enzymes were observed between the 3 different parasite strains at different pH values. A high degree of conservation in reactive peptides was observed when protein extracts were probed with antisera raised to the protective hidden gut-antigen complexes isolated from the Moredun strain of H. contortus, or to bacterially expressed subcomponents thereof. Therefore, despite the observed differences in membrane-bound proteinase profiles, the similarity of the immunogenic response against these hidden antigens may be sufficient to prove protective against different geographical isolates of H. contortus.

Molecular characterization of a novel serine proteinase from Trichinella spiralis and its participation in larval invasion of gut epithelium

“…Moreover, the proteolytic activity of rTsSPc was assayed by using azocasein (Sigma). The effect of pH on rTsSPc enzymatic activity to degrade azocasein was measured at pH 5.5–10.5 [ 53 ]. Briefly, 2 μg rTsSPc proteins were mixed with 25 μl buffer and 20 μl azocasein substrate (10 mg/ml) and incubated for at 37°C 16 h. Then, the assay was stopped using 50 μl 12% trichloroacetic acid at room temperature for 15 min and centrifuged at 12 000 × g for 20 min.…”