Establishment Of Quality Assessment On ELISA Commercial Kits Used In Porcine Reproductive And Respiratory Syndrome Virus Antibody

Porcine reproductive and respiratory syndrome(PPRS)strongly threatened pig industry quite a long time and caused huge economic losses.The commercial diagnostic kits have been widely used in animal quarantine work.A qualified diagnostic kit plays a key role in port animal quarantine.But some problems appeared in the application process of the commercial diagnostic kits.One important issue is the poor quality of the commercial kits.The different diagnostic kits got different results.Even the same brand kits obtained different results in various labs,which may affect the validity and accuracy of the port detection.Enzyme Linked Immunosorbent Assay(ELISA)is the major method for the PRRSV antibody detection in entry-exit ports.This article focused on the quality assessment of PRRS ELISA commercial kits.Five brands of PPRS ELISA commercial kits were selected in this research,including IDEXX,Biochek,Novegent,LSI and Fender.Through testing seven parameters:Diagnostic sensitivity(DSe),Diagnostic specificity(DSp),Analytical sensitivity(ASe),Repeatability(Re)and Reproducibility(Rp)of five brands ELISA kit,a quality assessment system of PRRS antibody ELISA kits was established.The process of assessment consisted of three steps.First of alll,18 sera provided by ACDC(OIE PRRS Reference Laboratory)were used to screening five brands kits.Secondly,the diagnostic performance characteristics of the qualified kits through screening were detected by 343 field samples.Finally,the analytical performance characteristics and homogeneity including Re and Rp were measured by GD reference sera.The Re of four brands kits was measured by two operators using the reference sera.Twenty samples were detected by four brands kit in three different laboratories in order to get Rp of kits.The results are as follows:Firstly,The Fender kit does not adapt to port quarantine because the accuracy of Fender kit was not good.The correct rate of Fender kit was-61%.The accuracy of other four brands kit was 100%.Secondly,IDEXX and Biochek can detect American type and European type virus antibody,and the Novegent and LSI can only detect American type antibody.The analytical sensitivity of Novegent was best.The analytical sensitivity from high to low was Novegent,IDEXX,Biochek,LSI.Thirdly,according to kappa values and ROC curve for the field samples results of four brands kits,IDEXX's results were closest to the indirect immunofluorescence assay(IFA)results.With IFA as the "gold standard",the four kits had 55 different results.The DSe of IDEXX,Biochek,Novegent and LSI was 94.58%,94.58%,96.55%,93.1%.The DSp of IDEXX,Biochek,Novegent and LSI was 97.14%,89.29%,85%,90%.Fourthly,the repeatability of Novegent was best.The inter-batch coefficient of variation of IDEXX,Biochek,Novegent and LSI was 18.23±17.89%,18.20±8.65%,8.07a±2.79%and 17.22b±6.29%.The intra-batch CV of IDEXX,Biochek,Novegent and LSI was 7.88±5.68%,11.34±5.60%,7.34±1.41%and 8.66±4.74%.Fifthly,the reproducibility except Biochek was good.The variation coefficient of Biochek in different laboratories reached 21.99%,the coefficient of variation of IDEXX,Novegent and LSI kit in different laboratories were less than 15%.Besides.IDEXX kit near period of validity appeared positive results on the negative samples detected.The kit near the shelf-life should be used with caution.