ESTABLISHMENT AND COMPARISON OF TWO PCR METHODS FOR THE DETECTION OF LABORATORY ANIMAL INFECTED WITH TOXOPLASMA GONDII

In order to establish a sensitive, specific and stable PCR technique for the detection of Toxoplasma gondii infection in laboratory animal. One pair of primers were designed and synthesized based on the sequence of Toxoplasma gondii B 1 gene for normal PCR. Two pairs of primers were designed and synthesized based on the sequence of Toxoplasma gondii P 30 gene for nested PCR. Both normal PCR and nested PCR were used for detecting DNA of Toxoplasma gondii in experimental infected KM mice, and the nested PCR was used for detecting conventional guinea pigs and rabbits. The result showed that the nested PCR was 100 times more sensitive than the normal PCR. DNA of Toxoplasma gondii could be detectable as little as 1fg, and with high specificity. No cross reaction was found with the DNA of the other microorganisms. Identical results were obtained when the same samples were tested for three times repeatedly. By using the nested PCR,DNA of Toxoplasma gondii could be detected as early as the second day after the experimental infection in KM mice with a positive rate of 83.3% in the abdominal cavity fluid, 33.3% in the blood, and reached 100% on the 3rd day in the fluid. By using the normal PCR, a positive rate of 16.7% was detected on the 3rd day in the addominal cavity fluid, 16.7% in the blood on the 4th day. The result of detection in conventional guinea pigs were all negative and showed a psoitive rate of 14.3% in rabbits. Conculsion: The nested PCR can be used for early diagnosis of toxoplasmosis in laboratory animal.