Development of rapid immunochromatographic test with recombinant NcSAG1 for detection of antibodies to Neospora caninum in cattle.

An immunochromatographic test (ICT) with recombinant surface antigen 1 of Neospora caninum (NcSAG1) was developed for the rapid detection of antibodies to N. caninum in cattle. The ICT was used to clearly discriminate between immunofluorescent-antibody test (IFAT)-positive bovine sera and IFAT-negative bovine sera. Serum samples collected from cattle in Yanbian, China, were examined by the ICT. Of the 96 serum samples, 23 (24.0%) were positive by the ICT, and 19 (19.8%) samples were positive by a previously developed enzyme-linked immunosorbent assay (ELISA). Eighteen of 19 ELISA-positive samples were positive according to the ICT. A good agreement was found between the results of the ICT and the ELISA. The results presented here suggest that the ICT with recombinant truncated NcSAG1 fused to glutathione S-transferase is a useful and reliable method for the detection of antibodies to N. caninum in cattle.