Improved preparation of ELISA antigen of infectious bursal disease virus

Serotype 1 of infectious bursal disease virus (IBDV) adapted to chicken embryo fibroblasts (CEF) was used for the preparation of enzyme-linked immunosorbent assay (ELISA) antigen. After several passages of diluted viruses in CEF cultures, the titer of seed virus increased to 1.2 x 10(8) plaque-forming units/ml. Purified virus prepared from this seed virus had high titers of antigen and was less nonspecific than that from low titer of seed virus in an ELISA. The nonspecific reaction of purified virus decreased further after treatment with Triton X-100. When the specificity of this treated antigen was examined with specific-pathogen-free chicken sera before and during lay and with 14 antisera to some major avian viruses, this ELISA antigen had no nonspecific reaction and was specific to antibodies to serotypes 1 and 2 of IBDV.