Cloning and analysis of a cDNA encoding a putative serine protease comprising two trypsin-like domains of Trichinella spiralis

Abstract

The cDNA encoding a putative serine protease, TsSerP, was cloned by degenerative polymerase chain reaction and screening of the cDNA library from Trichinella spiralis adult-newborn larvae stage. Sequence analysis revealed the presence of two trypsin-like serine protease domains flanking a hydrophilic domain, with the catalytic triad residue histidine in the alpha domain substituted by an arginine residue. Southern blots indicated that this was a single copy gene in the parasite genome. Northern blots demonstrated a single 2.3 kb transcript during the muscle larvae and adult stages of T. spiralis. The recombinant protein from the TsSerP beta domain (βSerP) was produced but not recognised by T. spiralis-infected swine serum. An anti-βSerP polyclonal serum detected a 69 kDa polypeptide in the soluble antigens of T. spiralis muscle larvae. Immunolocalisation analysis located TsSerP on the inner layer of the cuticle and oesophagus of the parasite, suggesting a potential role in its moulting and/or digestive functions. © Springer-Verlag 2005.