Abstract:

In recent years, the risk factors for Toxoplasma gondii infection in humans and animals have increased, so the investigation of the prevalence of T. gondii has become more important. In view of the fluorescence characteristics of lanthanide microspheres, such as long life span, large stockes displacement and excellent photostability, this study applied the fluorescent microspheres as probes for the detection of T. gondii antibodies in serum. In order to improve the accuracy of the test, a mixture of three antigens of soluble expressed SAG1, SAG2, and GRA1 was used as the coating antigens, and fluorescent microsphere-labelled SPA was used as the probe to develop test strips for the detection of T. gondii antibodies by indirect immuno-lateral chromatography, and the conditions of the sampling method, the co-incubation time of the microsphere and sera, the reaction time were optimized, meanwhile, the specificity, sensitivity, reproducibility and reliability of the test strips were investigated. The results showed that the prepared lanthanide microsphere immunochromatographic test strips have the following characteristics: good specificity, no cross-reactivity with other pathogenic sera; high sensitivity, the positive sera can still be detected at a dilution of 1 600 times; fast detection speed, the results can be obtained in as fast as 10 minutes; stable and reliable, the Kappa analyses of serum samples show that the lanthanide microsphere test strips have good consistency with the two ELISA assays. The present study provides a rapid, sensitive and quantitative immunochromatographic method for the detection of T. gondii antibodies.

Key words: lanthanide microspheres, immunochromatography, Toxoplasma gondii, immediate detection, quantification