重组酶介导的核酸等温扩增荧光法检测日本血吸虫感染性钉螺的效能评价

Performance of a recombinase-aided amplification assay for detection of Schistosoma japonicum infections in Oncomelania hupensis

目的评价重组酶介导的核酸等温扩增(recombinase-aided amplification,RAA)荧光法检测日本血吸虫感染性钉螺的效能。方法采用群体法检测。每50只钉螺作为1个检测样本,阴性样本不含感染性钉螺,阳性样本含不同数量感染性钉螺。设置阴性样本10个和分别含有1、2、3只感染性钉螺的阳性样本各10个,40个样本随机分组后,以盲法经荧光RAA法检测,并以逸蚴法检测结果为金标准,计算荧光RAA法检测灵敏度、特异度、正确指数及符合率。设置阴性钉螺样本5个和分别含有1、2、3只感染性钉螺的阳性样本各5个,20个样本随机分组后,采用配对设计法对同一个样本以盲法分别经压碎镜检法和荧光RAA法进行检测并比较检测结果。结果荧光RAA法检测30个阳性样本,29个检测结果为阳性,灵敏度为96.67%;检测10个阴性样本,其中8个检测结果为阴性,特异度为80.00%;约登指数为0.77,同一样本重复检测10次符合率为100%。荧光RAA法与压碎镜检法检测感染性钉螺结果差异无统计学意义(χ^(2)=0,P>0.05),检测结果与实际符合率分别为95.00%(19/20)和90.00%(18/20)。结论荧光RAA法对日本血吸虫感染性钉螺具有良好检测效能,在日本血吸虫感染性钉螺筛查中具有一定应用前景。

Objective To evaluate the efficiency of a recombinase-aided amplification(RAA) assay for the detection of Schistosoma japouicum infections in Oucomelania hupensis snails.Methods A group test was employed.Fifty Oncomelania snails were collected as a detection sample.The detection samples without infected snails were designated as negative specimens,while the detection samples that contained different numbers of infected snails were designated as positive specimens.A total of 10 negative specimens,10 positive specimens containing 1 infected snail,20 positive specimens containing 2 infected snails and 10 positive specimens containing 3 infected snails were assigned.Following random grouping,40 specimens were subject to the florescent RAA assay using a blind method.The miradium shedding method served as a gold standard,and the sensitivity,specificity,Youden’s index and coincidence rate of the florescent RAA assay were estimated.In addition,20 samples consisted of 5 negative specimens and 15 positive specimens with 1,2 and 3 infected snails respectively were grouped randomly.The same specimens were detected using the crushing method and fluorescent RAA assay with the blind method in a paired-design manner.Then,the test results were compared and analyzed.Results Florescent RAA assay detected 29 positives in the 30 specimens containing different numbers of infected snails,with a sensitivity of 96.67%,and 8 negatives in the 10 detection specimens without infected snails,with a specificity of 80.00%,showing a Youden’s index of 0.77.The coincidence rate was 100% among 10 repeated assays for a detection specimen.In addition,there was no significant difference in the detection of infected snails between the florescent RAA assay and the crushing method(χ^(2)=0,P> 0.05),and the actual coincidence rates of the florescent RAA assay and crushing method were 95.00%(19/20) and 90.00%(18/20) with the real results,respectively.Conclusion Fluorescent RAA assay has a favorable efficiency for the detection of S.japonicum infections in Oncomelania snails,which shows a potential in screening of S.japonicum-infected Oncomelania snails.