非标记探针结合高分辨熔解曲线分析快速区分第1类整合子可变区启动子

Differentiation of Pc and P2 variants in class 1 integron by high-resolution melting analysis

目的：建立一种基于非标记探针结合高分辨率熔解曲线分析快速区分第1类整合子可变区启动子种类的方法。方法 PCR扩增质粒pACW （PcW）、pACWP2（PcW－P2）含可变区启动子区域的DNA片段，再分别以纯化的PCR产物为模板，用扩增子高分辨率熔解曲线分析对P2启动子进行区分。以质粒 pACS （ PcS ）、pACH2（ PcH2）、pACH1（ PcH1）、pACW （ PcW ）及肺炎克雷伯菌HS07－68（PcWTGN－10）、HS05－1792（PcH2TGN－10）基因组DNA为模板，结合定点突变，PCR扩增获得分别含8种不同Pc启动子序列的DNA片段，再分别以纯化的PCR产物为模板，联合运用扩增子和非标记探针高分辨率熔解曲线分析对8种不同Pc启动子进行区分。运用上述方法对2004—2007年95株非重复分离自华山医院住院患者尿液标本的第1类整合酶阳性大肠埃希菌中可变区启动子进行分析，并与测序结果进行比对。结果 P2启动子扩增子熔解曲线的熔链温度（ Tm）值明显高于无活性的P2启动子，通过扩增子高分辨率熔解曲线分析可将两者区分开，95株大肠埃希菌109个第1类整合子中，有2个整合子中检测出P2启动子，与测序结果完全一致。8种不同的Pc启动子通过扩增子高分辨率熔解曲线分析分为3组：PcS、PcSTGN－10；PcW、PcWTGN－10；PcH1、PcH1TGN－10、PcH2、PcH2TGN－10。非标记探针高分辨率熔解曲线分析将8种不同的 Pc 启动子分为4组 PcS， PcH1；PcH2， PcW；PcSTGN－10， PcH1TGN－10；PcH2TGN－10，PcWTGN－10。联合运用扩增子和非标记探针高分辨率熔解曲线分析可将8种不同的Pc启动子相互区分开，95株大肠埃希菌109个第1类整合子中，共检测出5种不同的Pc启动子PcS，PcW，PcH1，PcH2TGN－10，PcWTGN－10，与测序结果完全一致。结论本研究成功建立了一种基于非标记探针结合高分辨率熔解曲线分析的方法，用于快速区分第1类整合子可变区启动子，该方法结果准确、费用低，可用于临床对第1类整合子可变区启动子多态性的研究。（中华检验医学杂志，2017，40：95－100）

Objective To develop a simple high-resolution melting （ HRM） analysis method for differentiation of Pc and P2 variants in class 1 integron.Methods DNA fragments containing Pc and P2 variants were amplified from plasmids pACW （ PcW ） and pACWP2 （ PcW-P2 ） respectively , then these purified PCR products and P 2 promoters were analyed full-length amplicon by HRM .Eight DNA fragments containing different Pc promoters were amplified and site-specific mutated from plasmids pACS （ PcS ） , pACH2 （ PcH2 ） , pACH1 （ PcH1 ） , pACW （ PcW ） , genomic DNA of Klebsiellar pneumonia HS07-68 （PcWTGN-10）and HS05-1792（PcH2TGN-10）respectively.The purified PCR products and eight Pc variants were characterized by HRM analyses of an unlabeled probe and full-length amplicon.This assay was applied to the differentiate Pc and P2 variants in 109 class 1 integrons from 95 urine clinical Escherichia coli isolates in Huashan Hospital during 2004 -2007.The differentiation results were compared with that determined by direct sequencing .Results P2 promoter with a significant higher melting temperature （ Tm ） can be identified by HRM analysis clearly .P2 promoters were identified in 2 class 1 integrons and consistent with＆amp;nbsp;direct sequencing results .Eight Pc variants were classified into three groups： PcS, PcSTGN-10 , PcW, PcWTGN-10, PcH1, PcH1TGN-10.Using direct HRM analysis.PcH2, PcH2TGN-10 were classified into four groups：PcS, PcH1, PcH2, PcW, PcSTGN-10 , PcH1TGN-10 , PcH2TGN-10 , PcWTGN-10 according to the melting curves of the unlabeled probe .Combined the HRM analyses of the whole amplicon and unlabeled probe , the eight Pc variants can be differentiated from each other .Five different Pc variants, PcS, PcW, PcH1, PcH2TGN-10 and PcWTGN-10 , were identified and consistent with direct sequencing results .Conclusions This developed a simple Pc and P 2 variants differentiation method via simultaneous HRM analyses of an unlabeled probe and full-length amplicon .This method is cost-effective and accurate , could be used in differentiation of Pc and P2 variants of class 1 integrons in clinical isolates .