Two-dimensional immunoblot analysis of antigenic proteins of Spirometra plerocercoid recognized by human patient sera

Sparganosis is caused by invasion of Spirometra plerocercoid into various tissues/organs. Subcutaneous sparganosis can be diagnosed and treated by worm removal, while visceral/cerebral sparganosis is not easy to diagnose. The diagnosis depends largely on the detection of specific antibodies circulating in the patients' sera. Previous studies demonstrated that 31 and 36 kDa proteins of the sparganum invoked specific and sensitive antibody responses, but also showed cross reactions with cysticercosis sera. We enriched protein fractions containing 31–36 kDa through gel filtration and examined immune recognition pattern against the patient sera by 2-dimensional electrophoresis (2-DE) followed by immunoblotting. Serum samples from sparganosis patients recognized 8–10 protein spots of 31 and 36 kDa with different isoelectric point (pI) values with variable combinations, in which four spots of 31 kDa with pIs 3.4, 3.9, 4.0 and 4.1, and one 36 kDa spot (pI 3.5) appeared to be specifically reactive. One 31 kDa protein spot with pI 3.3 and two spots of 36 kDa with pIs 3.3 and 3.5 reacted crossly with neurocysticercosis sera. Neither sera from patients with other parasitic infections nor those from healthy controls showed positive reaction. Two-DE/immunoblot analysis might be highly available in differential serodiagnosis of human sparganosis.

Graphical AbstractIdentification of specific- and cross-reactive protein spots of the 31 and 36 kDa of the sparganum extracts by 2-dimensional immunoblotFigure optionsDownload as PowerPoint slideResearch Highlights
► We investigate the serodiagnostic applicability of sparganum 31- and 36-kDa proteins.
► The 31- and 36-kDa antigens comprise multiple spots with different pI values.
► Some of the major antigen spots cross-react with cysticercosis patients' sera.
► Four protein spots are found to be specific against sparganosis patients' sera.
► Two-dimensional immunoblot is highly reliable for the serodiagnosis of sparganosis.