Evaluation of indirect-ELISA using eluted antigens from Trichinella spiralis muscle larvae for diagnosis of swine trichinellosis

Trichinellosis is caused by Trichinella spiralis muscle larvae (TsML), which is transmitted to human when they eat infected raw or undercooked meat. T. spiralis infection is detected by an enzyme-linked immunosorbent assay (ELISA) using excretory–secretory antigens (ESAg); however, the preparation of ESAg is challenging, and yields are low, which hampers screening efforts. In this study, crude somatic antigens (CSAg) of TsML with molecular weights (MWs) of 43, 79 and 101 kDa have been identified in swine trichinellosis sera with less cross-reaction with uninfected sera and other parasitic infected sera. After that, the CSAg at MWs of 43, 79 and 101 kDa (TsCSAg-43, TsCSAg-79, and TsCSAg-101, respectively) were isolated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The eluted antigens were analyzed by IgG-ELISA for sensitivity and specificity, and specific antigens from the three regions were identified by two-dimensional polyacrylamide gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The sensitivity of IgG-ELISA using the three eluted antigens was 100% with specificities of 97.77%, 95.54%, 90.63% and for TsCSAg-43, TsCSAg-79, and TsCSAg-101, respectively. The LC-MS-MS results of immunomics showed that 18/20 spots of the antigens with MWs of 43, 79, and 101 kDa represent 11 different proteins identified. TsCSAg-43 showed the highest specificity, indicating that the specific proteins identified, including 45 kDa antigen–trichina [fragment], DNA topoisomerase 2-alpha antigen targeted by protective antibodies, and a conserved hypothetical protein (gi339234223), should be developed and produced in large volumes for further immunodiagnostic studies.