DETECTION OF ANTIBODIES TO NEWCASTLE-DISEASE VIRUS IN OSTRICHES (STRUTHIO-CAMELUS) BY AN INDIRECT ELISA

A two-graph receiver operating characteristic analysis, performed on t he hemagglutination-inhibition (HI) and enzyme-linked immunosorbent as say (ELISA) test results of a Newcastle disease virus (NDV)-positive a nd NDV-negative control group of ostrich sera, proved that the ELISA w as superior to the HI in both sensitivity and specificity. Comparison of results of the two assays performed on a panel of simulated positiv e sera ranging from very weak to very strong showed that the ELISA was at least 10 times more sensitive than the HI in detecting low levels of ostrich antibodies to NDV. The ELISA also has the advantage of usin g untreated serum in a single dilution as opposed to the HI test, whic h uses pretreated serum in titration.