Abstract: 　Objective To study the significance of DNA of Toxoplasma gondii in peripheral blood. Methods DNA of T.gondii in peripheral blood of 50 infected rats was detected by polymerase chain reaction. A pair of primers was designed, according to the sequence P30 gene specific to T.gondii, to amplify DNA from T.gondii by PCR. Results The primers amplified DNA specifically from T.gondii and could not amplify DNA from humans, uninfected rat and mouse and from Trichomonas vaginalis and Entamoeba histolytica. DNA of two Toxoplasma parasites was detected by 35 cycles of amplification, indicating a fair sensitivity of the PCR system. Conclusion PCR may have a value for early diagnosis of T.gondii infection in rat.

Key words: polymerase chain reaction, primer, Toxoplasma gondii