Porcine cysticercosis: first evaluation of antigens from the liquid of cyst for the development of a serological test for Livestock

Abstract

Abstract Background: In low-income countries, rapid discard of cysticercosis suspected pigs from the meat chain, is a key step to preserve customers. Unfortunately, in most place only rapid visual inspection of carcasses is practiced. Despite their fluctuant specificity serological tests performed in living animals before entry at slaughterhouse, could be a better and easier approach to promote. However, recombinant antigens must be developed and evaluated to improve accessibility of serological diagnosis. In this study, five recombinant antigens have been expressed and evaluated in Elisa in comparison with electro-immune transfer blot (EITB). Results Antigens were expressed in a baculovirus-insect cell system, purified by affinity chromatography and evaluated on pig serum. Sensitivity, specificity, concordance, and positive likelihood ratio of each recombinant antigen were calculated in reference to EITB. Sensitivityvalues ranged from 43.9% (34.5 - 53.8) to 88.8% (80.8 - 93.7). Specificities ranged from 37.5% (28.5 - 47.5) to 65.6% (55.7 - 74.3). To improve performance of the tests, combination of antigens was used rising sensitivity between 90.8% and 94.9%. Compared to visual examination of carcasses as performed in slaughterhouses these combinations only missed 1% to 5% of infection. Specificities were lower but at the same level as the native antigen ELISA. Conclusion: These recombinant antigens have sensitivity and specificity in the same range as EITB and can be now evaluated against the necropsy as gold standard. Using such tests, cysticercosis suspected animals could be treated with oxendazole before entering the market chain to improve the management of animals at the farm level.