Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: Characterization of HC58cDNA, a putative cysteine protease from the parasite Haemonchus contortus | J. Vet. Set. 2006 7 3 249-255 JOURNAL OF Veterinary Science Characterization of HC58cDNA a putative cysteine protease from the parasite Haemonchus contortus Charles I. Miileke Yan Ruofeng Xu Lixin Sun Yanming Li Xiangrui College of Veterinary Medicine Nanjing Agricultural University Jiangsu 210095 PR China Because of the complexity of the cathepsin B-like CBL family an information on the biological and biochemical characteristics of individual CBL genes is lacking. In this study we investigated the degradative effects of the recombinant HC58 protein isolated from Haemonchus contortus parasites on protein substrates over a broad pH range in vitro. This protein which hydrolyzed the synthetic peptide substrates Z-FR-AMC and Z-RR-AMC had characteristics of the cysteine protease class of proteins. In the acidic pH range the isolated protein actively degraded hemoglobin Hb the heavy chain of goat immunoglobulin G and azocasein. By contrast it degraded fibrinogen in the alkaline pH range. These activities were strongly inhibited in the presence of the cysteine protease inhibitor E-64. While the protein digested Hb it did not induce the agglutination of erythrocytes from its natural host. These results suggest that the HC58 protein may play a role in the nutrition of this parasite. Key words cysteine protease activity Haemonchus contor-tus recombinant HC58 protein synthetic peptide substrates Introduction Haemonchus contortus is a highly pathogenic parasite affecting sheep goats and cattle. The adult parasite causes severe anemia weight loss and death especially in young animals 12 The adult nematode located in the abomasum of ruminants derives nutrients through bloodfeeding and the ingestion of tissue debris. After the proteolytic anticoagulants of Ảncylostomum hookworms were first described 6 a considerable amount of interest arose in the role of proteinases in the maintenance of bloodfeeding parasitic helminthes 20 . The digestive proteases of schistosomes were .
