Comparison of two commercial enzyme-linked immunosorbent assays and conventional methods for avian serology

Sera tested for hemagglutination-inhibition (HI) activity against Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) and virus-neutralizing (VN) activity against infectious bursal disease virus (IBDV) and viral arthritis (VA) virus were collected from a wide variety of accessions into the Diagnostic Services Laboratory, Poultry Disease Research Center, University of Georgia. The sera were then segregated according to HI or VN titer to NDV, IBV, IBDV, or VA virus and stored frozen at -20 C until tested by two commercial enzyme-linked immunosorbent assays (ELISAs). There was good correlation of mean Flockchek ELISA titers or EIA Systems sample-to-positive (S/P) ratios with specific HI or VN titers. Flockchek ELISA profile group 3 and EIA Systems mean S/P ratio of 1.12 corresponded to what were considered in our lab to be minimum protective titers for each antigen against virulent challenge in our area.