The influence of сestodes parasitizing in the small intestine of herring gull chicks on the activity of the host proteases

The activity of proteases and subclasses of proteases in small intestines of the herring gull (Larus argentatus (Pontoppidan, 1763)) chicks were determined. Changes of the protease activity in chicks infested by cestodes Tetrabothrius erostris (Loennberg, 1889) (Cestoda: Tetrabothriidae), Microsomacanthus ductilus (Linton, 1927) (Cestoda: Hymenolepididae), Wardium cirrosa (Krabbe, 1869) (Cestoda: Aploparaksidae), Arctotaenia tetrabothrioides (Loennberg, 1890) and Alcataenia larina (Krabbe, 1869) (Cestoda: Dilepididae) were studied. The activity of serine proteases decreased in the small intestine of gulls at the sites of cestode parasitism with high infestation values (M. ductilus in the proximal segment, W. cirrosa in the distal segment, A. tetrabothrioides, T. erostris and A. larina in the medial segment). The activity of cysteine proteases increased in the sites of localization of cestodes M. ductilus, W. cirrosa and A. larina. All the studied cestodes adsorbed proteases on the surface of the tegument, most of those were represented by serine proteases. Cestode homogenates of W. cirrosa, M. ductilus, A. tetrabothrioides, T. erostris and A. larina inhibited the activity of host proteases and the activity of commercial trypsin.