PEDV与TGEV双重荧光RT-LAMP检测方法的建立与评价

Establishment and evaluation of a dual fluorescent RT-LAMP assay for PEDV and TGEV detection

为建立可快速鉴别检测猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)和猪传染性胃肠炎病毒(transmissible gastroenteritis virus,TGEV)的双重荧光RT-环介导等温扩增(loop-mediated isothermal amplification,LAMP)方法,从GenBank下载PEDV和TGEV不同毒株M基因序列进行比对后,针对高度保守区设计合成内、外引物对和探针,在PEDV探针5′端标记FAM基团,3′端标记BHQ1基团,在TGEV探针5′端标记CY5.5基团,3′端标记BHQ2基团,对反应条件和体系优化后建立了一种快速鉴别PEDV和TGEV的双重荧光RT-LAMP检测方法。采用建立的方法在63℃水浴锅中反应60 min,然后再85℃作用10 min结束反应,将反应管置于多色荧光成像仪,在520、690 nm双通道下即可观察结果。用该方法检测其他猪常见病毒性病原均无交叉反应;以10倍稀释的重组质粒为模板评价该方法的灵敏度,结果最低检测限为10^(2)拷贝/μL重组质粒,是常规RT-PCR方法敏感度的10倍。从175份有腹泻症状仔猪的肛拭子样品中采用建立的方法共检出PEDV阳性样品72份,TGEV阳性样品49份,PEDV和TGEV混合感染样品40份,均比采用常规RT-PCR方法的检出率高。本研究建立的双重荧光RT-LAMP方法采用普通水浴锅即可进行扩增反应,而无需对反应产物进行凝胶电泳,为快速方便的进行PED与TGE的鉴别诊断和PEDV与TGEV混合感染的同步检测提供了技术支撑。

To develop a rapid differential detection method for porcine epidemic diarrhea virus(PEDV)and transmissible gastroenteritis virus(PEDV),M gene sequences of PEDV and TGEV were compared,the inner and outer primer pairs and probes were designed according to the highly conserved region.PEDV-Probe was labeled with FAM at 5′end and BHQ1 at 3′end.TGEV-Probe was labeled with CY5.5 at the 5′end and BHQ2 at the 3′end.After optimizing the reaction conditions and system,a dual fluorescent RT-LAMP assay for PEDV and TGEV rapid identification was established.The amplification could be completed within 60 min in a 63℃water bath and then stopped at 85℃for 10 min.Then the tubes were placed in a multicolor imaging system,and the results could be observed under 520 nm and 690 nm dual channels.There was no cross-reaction when other common swine viral pathogens were detected by this method.The sensitivity of the assay was evaluated with a 10-fold diluted recombinant plasmid as templates.The lowest detection limit was 10^(2)copies/μL recombinant plasmid,which was 10 times more sensitive than the conventional RT-PCR method.Seventy-two PEDV-positive samples,49TGEV-positive samples,and 40PEDV and TGEV co-infected samples were detected from 175anal swab samples of diarrheic piglets by the established method,which were all higher than the detection rates of the conventional RT-PCR method.The dual fluorescent RT-LAMP method established in this study can be used to amplify the target gene in an ordinary water bath without gel electrophoresis,which provides technical support for rapid and convenient differential diagnosis of PED and TGE and simultaneous detection of PEDV and TGEV co-infection.