Evaluation of four enzyme linked immunosorbent assays for the detection of antibodies to infectious bursal disease in chickens.

The routine technique for detecting antibodies specific to infectious bursal disease virus is a serological evaluation by enzyme linked immunosorbent assay (ELISA) with preparations of whole virions as antigens. To avoid the use of complete virus in the standard technique, in-house VP2 and VP3 based ELISAs were developed. Accordingly, four types of indirect ELISAs viz., a commercial IDEXX-ELISA kit, VP2 and or VP3 antigen based ELISAs and a whole virus ELISA were compared with the virus neutralization test. It was concluded that the sensitivity and specificity at receiver-operating characteristics (ROC) optimized cut-off of four ELISAs viz., IDEXX-ELISA, VP2-ELISA and VP3-ELISA indicated similar performance whereas whole virus antigen based ELISA showed poor performance in comparison to other ELISAs. Similarly the positive and negative likelihood ratio of four ELISAs at an optimized cut-off indicated IDEXX-ELISA to be the best among all the four ELISAs while the performance of rVP3-ELISA and rVP2-ELISA is good as compared to the whole virus ELISA. Finally, the area under the ROC curve (AUC) of four ELISAs which represented a summary statistics of the overall diagnostic performance of the test also indicated that the IDEXX-ELISA, VP3-ELISA and VP2-ELISA had similar and relatively better performance when compared to whole virus antigen-ELISA.