Expression of schistosomal cathepsin L1 in Escherichia coli and evaluation of its protective capacity in an animal challenge

ABSTRACT

Schistosomes use proteinases to accomplish some tasks such as tissue penetration, tissue digestion for nutrition and evasion of host immune responses. The Cathepsin L is a cysteine proteinase of the papain superfamily detected in the gut lumen indicating that this enzyme contributes to the proteolysis of ingested hemoglobin. Due to these roles they play in the schistosome biology, proteolytic enzymes are considered potential targets to develop and direct anti-schistosomal therapies. In this work, the cDNA coding Cathepsin L1 of Schistosoma mansoni was cloned into the pAE vector that provides high-level expression of heterologous proteins in Escherichia coli. The recombinant protein was expressed as inclusion bodies, purified under denaturing conditions through nickel charged chromatography and used for experimental animal vaccination. ELISA was performed with the pooled sera. Although this protein showed to be immunogenic, mice immunized with three doses of recombinant protein plus aluminum hydroxide as adjuvant did not protect against S. mansoni infection.