TsAg5, a Taenia solium cysticercus protein with a marginal trypsin-like activity in the diagnosis of human neurocysticercosis

Neurocysticercosis is an endemic parasitic disease caused by Taenia solium larva. Although the mechanism of infection is not completely understood, it is likely driven by proteolytic activity that degrades the intestinal wall to facilitate oncosphere penetration and further infection.We analyzed the publicly available T. solium EST/DNA library and identified two contigs comprising a full-length cDNA fragment very similar to Echinococcus granulosus Ag5 protein. The T. solium cDNA sequence included a proteolytic trypsin-like-domain in the C-terminal region, and a thrombospondin type-1 adherence-domain in the N-terminal region. Both the trypsin-like and adherence domains were expressed independently as recombinant proteins in bacterial systems. TsAg5 showed marginal trypsin-like activity and high sequence similarity to Ag5. The purified antigens were tested in a Western immunoblot assay to diagnose human neurocysticercosis. The sensitivity of the trypsin-like-domain was 96.36% in patients infected with extraparenchymal cysts, 75.44% in patients infected with multiple cysts, and 39.62% in patients with a single cyst. Specificity was 76.70%. The thrombospondin type-1 adherence-domain was not specific for neurocysticercosis.

A Taenia solium recombinant antigen homologous to Echinococcus granulosus Ag5 with a trypsin-like domain and an adherence-domain is characterized and tested as an immunodiagnostics antigen.Figure optionsDownload high-quality image (116 K)Download as PowerPoint slideHighlights
► TsAg5 was found in the excretory/secretory antigens of the cysticercus and in the oncosphere.
► The trypsin-like domain of TsAg5 showed a marginal proteolytic activity.
► The trypsin-like domain showed to be an important antigen for immunodiagnostics of multiple cyst and extra-parenchymal NCC.
► The adherence domain of TsAg5 was not specific.