Comparison of a kinetic-based enzyme-linked immunosorbent assay (KELISA) and virus-neutralization test for infectious bursal disease virus. II. Decay of maternal antibody in progeny from white Leghorns receiving various vaccination regimens.

A computer-assisted single-serum-dilution indirect kinetic-based enzyme-linked immunosorbent assay (KELISA) was used for quantitating the natural decay rate of infectious bursal disease virus (IBDV) maternal antibody in progeny obtained from white leghorn breeders. The KELISA results were compared with those of a standard virus-neutralization (VN) test. Pullets were subjected to two IBDV immunization regimens. Group 1 was vaccinated at weeks 0, 2, and 10 with two live vaccines in drinking water and at week 20 with an oil-emulsified (SC) IBDV vaccine, group 2 received only the first and last immunizations, and group 3 served as the unvaccinated control. Pullets were artificially inseminated at 28 weeks of age. Progeny chicks from each group were bled every other day for 47 days. Both KELISA and VN test detected linear relationship in the decay of maternal antibodies. The VN test detected no significant differences (P greater than 0.05) in the IBDV maternal antibody titers at day 1 or in the rate of decay between the progeny from groups 1 and 2. The VN maternal antibody titers decreased at a rate of 0.16 log2 titer per day. In contrast, KELISA revealed higher IBDV maternal antibody titers in day-old progeny from pullets vaccinated 4 times (log2 = 14.3). However, KELISA titers of progeny from this group decreased at a faster rate than titers of progeny from pullets vaccinated twice (0.20 vs. 0.13 log2 titer per day).