聚合酶链反应检测弓形虫核酸的研究

应用聚合酶链反应（ＰＣＲ）技术，设计了一对寡核苷酸引物，对弓形虫Ｂ１基因的保守序列进行体外扩增，显示该引物只对弓形虫核酸扩增，可对４个或４个以上弓形虫扩增出明显条带，检测弓形虫核酸的最低量为２．５ｐｇ。该ＰＣＲ对急性感染弓形虫的小鼠，于４８ｈ后就可从部分小鼠（２／５）的外周血中检测到弓形虫核酸，９６ｈ后全部小鼠（５／５）外周血中均检测到弓形虫核酸，而感染２４ｈ后可从其肝、脾、肾等组织中扩增到弓形虫核酸。对３４例孕妇外周血分别用ＥＬＩＳＡ及ＰＣＲ平行检测，ＥＬＩＳＡ测ＩｇＭ阳性者３例，ＰＣＲ扩增阳性者６例（其中３例ＩｇＭ亦阳性），表明ＰＣＲ具有较高的敏感性和特异性。

STUDY ON DETECTING DNA OF TOXOPLASMA GONDII USING POLYMERASE CHAIN REACTION

We designed and synthesized a pair of oligonucleotide primers according to the sequence of the B1 gene specific for Toxoplasma gondii, to amplify and detect the DNA of T. gondii by PCR. The assay only can amplify T. gondii DNA except for DNAs from various organisms, including human, mouse,Plasmodium falciparum and Schistosma, etc. It was able to amplify and detect four and more tachyzoites or minimum amount of 2.5 pg T. gondii DNA. In animalmodel of acute infected toxoplasma,the T. gondii DNA was not detected from the peripherial blood of 2/5(5/5) mice infected until 48(96)hrs, meanwhile,it was not detectd from the livers, speens, kidneys of all the infected mice until 24 hrs. In the thirty-four samples of peripherial blood from pregnant women,using ELISA and PCR to detect parallelly, the result showed: 3 samples were positive by PCR or ELISA,3 samples which were negative by ELISA were positive by PCR. These results indicated that PCR was not only specific but also sensitive.