Protease Activity in the Small Intestine of the Northern Fulmar Fulmarus glacialis Infested with Tetrabothrius minor (Cestoda, Tetrabothriidae)

The effect of Tetrabothrius minor (Cestoda, Tetrabothriidae) infestation on the protease activity in the small intestinal mucosa was studied in the northern fulmar Fulmarus glacialis . We addressed various aspects of changes in total protease activity and the activity of different protease subclasses (metalloproteases, serine proteases, cysteine proteases) during tetrabothriid infestation, as well as the ability of T. minor to inactivate intestinal mucosal proteases and commercial trypsin. Total proteolytic activity was found to be reduced at the T. minor localization sites (proximal and medial segments of the small intestine) due to a decrease in the activity of serine proteases and metalloproteases. Protease activity in the host small intestinal mucosa was inversely related to the degree of parasite infestation: the higher the intensity of T. minor infestation, the lower the activity of proteases, including metalloproteases and serine proteases. T. minor homogenates inhibited the activity of proteases from the F. glacialis small intestinal mucosa, as well as the activity of commercial trypsin of different concentrations.