Study of a PCR-ELISA assay for the detection of Toxoplasma gondii DNA

In order to establish a rapid PCR-ELISA assay with high sensitivity, specificity and reliability for the detection of Toxoplasma gondii DNA in infected animals, the biotiny-labeled PCR products of Toxoplasma gondii DNA were hybridized with a specific digoxigenin-labeled probe, and then the infection with Toxoplasma gondii was determined by a colorimetric assay. The detection threshold was determined and compared with that of agarose gel electrophoresis. Similarly, DNA from Humans, mice, Plasmodium yoelii and Trichinella spiralis were also tested to determine the specificity. Moreover, the same sample was detected 5 times respectively at different time to determine the reliability. In addition, the mice were injected intraperitoneally with 10 4 and 10 3 tachyzoites respectively, and then the liver tissue and blood samples were collected and DNA of Toxoplasma gondii in these specimens were detected by PCR-ELISA assay. In this study, the detected threshold was 20 fg of Toxoplasma gondii DNA, and its sensitivity was ten times as much as that of agarose gel electrophoresis. And there was not any cross-reaction with the DNA from Humans, mice, Plasmodium yoelii and Trichinella spiralis . Furthermore the 5 repeated results of the same sample showed a better reliability according to reliability test (Alpha=0.72). Besides these, in both liver tissue and blood samples, Toxoplasma gondii DNA could be detected on the second day and the third day after infection respectively in 10 4 and 10 3 groups. Statistically,there was no difference between the positive detective rate of blood samples and that of liver tissue( P 0.05).In summary, the PCR-ELISA assay is a rapid method with high sensitivity, specificity and reliability, and it can be used as a diagnostic test for the detection of Toxoplasma gondii in clinical laboratories, and also serves as an important tool for epidemiological investigation.