Establishment Of Indirect ELISA For Detecting Haemophilus Parasuis Disease Based On CdtB

In the present study, an indirect-ELISA(rCdtB-ELISA) for the detection of the antibody against Haemophilus parasuis in serum was established using the prokaryotic expressed subunit of cytolethal distending toxin(rCdtB) as coating antigen. The rCdtB-ELISA was high specificity for detection of the antibody against H.parasuis, but no cross-reactions to the positive serums of TGEV, PRV, PCV2, CSFV, PEDV, PRRSV, E.coli, SS2, Pm, and APP. The coefficient of variation of intra- and inter batch repeatability test was lower than 7% and 8%, respectively.Moreover, comparison of the established rCdtB-ELISA with the commercial ELISA(BioChek HPS-OppA kit) for detection of 116 positive and 112 negative sera to H.parasuis, the results showed that the positive concordance rate was 25%, the negative concordance rate was 100%,and the total concordance rate was 62%. While, a total of 330 clinical sera samples were detected using the rCdtB-ELISA, it showed that the positive rate of H.parasuis was 11.8%.Application this method on the shelf life of H.parasuis 7 positive sera and 4 negative sera, the S/P value of positive serum were more than 0.2417 after six months, the S/P values of negative serum were less than 0.2417, it proved rCdtB-ELISA kit can be kept at least six months.