梅毒螺旋体的巢式PCR检测与基因分型

目的探讨广州地区梅毒螺旋体基因型分布,确定其分子流行病学特点。方法收集2002-2004年间连续就诊的疑似梅毒患者的生殖器溃疡标本,用暗视野显微镜和巢式PCR检测梅毒螺旋体,阳性者进行巢式PCR扩增酸性重复蛋白基因(arp)和苍白螺旋体重复基因族(tpr),凝胶电泳分析arp基因重复序列个数和tpr基因的MseⅠ酶切片段多态性。根据Pillay标准基因分型。结果共检测62例疑似硬下疳病例,33例(53．2％)暗视野镜检发现梅毒螺旋体；54例PCR检测阳性,阳性率为87.1％。47例arp基因分型以14型为主(36例占76.6％),49例tpr基因分型以d型为主(39例占79.6％),47例双重基因分型发现7个基因型,依次为14 d 31例占66.0％,13 d 5例占10.6％,14 b 4例占8.5％,12 b 3例占6.4％,12 d 2例占4.3％。15 d和14 i各1例占2.2％。结论巢式PCR法检测梅毒螺旋体具有较高的敏感性,广州地区梅毒螺旋体基因型以14 d型为优势型。梅毒的早期诊断和基因分型对于梅毒的防治有重要意义。

Detection and Genotyping of Treponema pallidum by a Nested PCR

Objective To develop a nested PCR for the detection of early syphilis and genotyping of Treponema pallidum (TP), and to investigate the distribution of genotypes of TP in Guangzhou. Methods Specimens were consecutively collected from genital ulcers of patients with suspected chancre during 2002-2004, and were detected by dark-field microscopy and nested PCR. The acidic repeat protein (arp) gene and the T. pallidum repeat (tpr) gene family were amplified with the positive specimens above. The number of repeats presented in the arp gene and the restriction fragment length polymorphism by Mse I in the tpr gene were analyzed by electrophoresis. The strains were genotyped according to Pillay's criteria. Results Out of 62 patients with suspected chancre, 33 cases (53.2%) were positive by dark-field microscopy and 54 cases (87.1%) by nested PCR. Of 47 TP-positive specimens genotyped by arp gene, 36 (76.6%) were type 14, while of 49 cases genotyped by tpr gene 39 (79.6%) were type d. By combining genotypes of arp and tpr genes, 7 genotypes were found, including 14d (31, 66.0%), 13d (5, 10.6%), 14b (4, 8.5%), 12b (3, 6.4%), 12d (2, 4.3%), 15d(l, 2.2%) and 14i (1, 2.2%). Conclusions Nested PCR shows a high sensitivity in early detection of TP. Genotype 14d seems the predominant type of TP in Guangzhou.