Specificity of affinity-purified Trichinella spiralis antigens

An affinity-purified fraction (APF) was obtained by passing crude somatic antigens of Trichinella spiralis muscle larvae through an Affi-Gel 10 column coupled with anti-Trichuris suis IgG. The fraction contained seven antigens with molecular weights ranging from 28 to 55 kDa. When tested with antiserum against other common nematodes of pigs from China, the APF was found to be markedly more specific than S3 antigens (prepared by a combination of cell fractionation and differential centrifugation according to Despommier and Lacetti, 1981) and fractions produced by Sephacryl S-200 gel filtration (F1 to F12). When the APF was used in an indirect IgG-enzyme-linked immunosorbent assay (IgG-ELISA) to screen serum samples from 2000 pigs imported from China, a positive rate of 7.5% was obtained. Similar screenings using the crude somatic antigens F1 and S3 gave a large number of cross-reactions and false positive reactions. Positive rates of 48%, 39% and 59.5% respectively were obtained for the three antigens.