Protease activity in the excretory-secretory products of nymphal stage of Linguatula serrata: First detection of a metalloprotease

The aim of this study was to evaluate the presence of proteases and determine the main protease present in the excretory-secretory products (ESPs) from nymphal stage of Linguatula serrata. Infected mesenteric lymph nodes of goats were collected from Tabriz slaughterhouse, northwestern Iran. Recovered Linguatula serrata nymphs were immersed in culture medium (MEM), then ESPs were collected and protease activity in presence of specific inhibitors was assayed. Protease enzyme was further characterised by SDS-PAGE. The results of this study showed that the main protease in the ESPs from the nymphal stage of L. serrata was a metalloprotease that was resistant to heat. In conclusion, these data show that a major protease secreted by the larval stage of L. serrata exhibited properties that may play a role in the pathogenesis of L. serrata nymphs.