ABSTRACT
The sonicated egg extracts and hatching fluid taken at different developmental stages of T. canis embryonated eggs and the excretory-secretory products of cultivated infective larvae were studied for their proteinase activity. It was found that the enzyme activity was elevated at 18 days of embryonation and reached the maximum at 32 days in the sonicated extracts and hatching fluid. This clarified the role of the enzyme in hatching process. Again, a definite proteinase activity in the excretory-secretory products of cultivated infective larvae was proved in this study. This activity varies with different pH and temperature and reached a maximum at pH 8 and 55C. This biological activity helps the larvae to live and migrate for long periods in a wide variety of tissues with different environmental conditions. The proteolytic activity of the hatching fluid and excretory-secretory products were inhibited by immune serum against T. canis infection. These findings proved that both secretions have an immunogenic property which may provide new targets for selective chemotherapy and vaccination