Authors
P C Hanington1; A L Kabore1; E A Pila1; 1 Univeristy of Alberta, Canada Discussion
A number of metalloproteases (MP) have demonstrated roles in immune modulation. In some cases, these enzymes are produced by parasites to influence host immune responses such that parasite infection is facilitated. One of the best examples of this is the matrixmetalloprotease leishmanolysin (Gp63), which is produced by leishmania in order to evade killing by macrophages. Leishmanolysin-like proteins appear to be quite common in many invertebrates, however our understanding of the functions of these non-leishmania enzymes is limited. Numerous proteomic and transcriptomic screens of schistosomes at all life cycle stages has identified leishmanolysin-like MPs as being present in abundance; with the highest levels being found during the intramolluscan larval stages and being produced by cercariae. This study aimed to functionally characterize a variant of leishmanolysin that most resembled the enzyme produced by leishmania, termed SmLeish. We demonstrate that SmLeish is an important component of S. mansoni excretory/secretory products and is also present on the sporocyst surface. The presence of SmLeish interferes with the migration of Biomphalaria glabrata haemocytes, and causes them to present a round, non-adherent phenotype. Knockdown of SmLeish in S. mansoni miracidia prior to exposure to B. glabrata causes a delay in reaching patent infection, and also reduced miracidia penetration success and ultimate cercaria output from infected snails. 
