The <i>Trichinella </i>genus can be broadly divided into two clades that differ in respect to the formation of the host-parasite complex within the muscle cell.  Parasite excretory/secretory (ES) proteins may be responsible for the developmental modification of host cells, as well as the differences observed between the two clades.  Serine proteases are known to be involved in parasite tissue/cell degradation and invasion, and are abundant in the ES protein fraction of mature L1 larvae (ML) of <i>Trichinella spiralis </i>and <i>Trichinella pseudospiralis </i>(representative of the two clades).  Presented here is analysis of the <i>T. spiralis </i>secreted ML serine protease, TspSP-1 and its <i>T. pseudospiralis </i>homologue TppSP-1.  Using the <i>T. spiralis </i>draft genome assembly TspSP-1 was shown to be encoded by a multi-copy gene family, with three genes tandemly repeated.  The putative proteins share high levels of similarity at the N-terminus, which includes the catalytic domain and potentially all encode functional serine proteases.  Comparative analysis of TppSP-1 was carried out and at least one full length cDNA transcript was characterised, though initial results indicated that TppSP-1 may also be encoded by a multi-copy gene family.  Based on TspSP-1, the putative TppSP-1 protein also contained a catalytic domain, though it was lacking one of the catalytic triad residues, indicating a loss of serine protease function.  Several serine protease homologues that have lost catalytic residues have gained other functions, which may also be the case for TppSP-1.  Given the timing of expression is it possible that TspSP-1 and TppSP-1 may be involved in the invasion of the intestinal epithelial cells.  Whether or not these proteins interact with host or parasite proteins and function as typical serine proteases is yet to be determined.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on July 14, 2009). Includes bibliographical references.