Monitoring the immune status of broiler breeders against infectious bursaldisease virus using progeny challenge and serologic data

Infectious bursal disease virus (IBDV)-induced immunosuppression causes sub optimum performance in broilers. Integrators use enzyme-linked immunosorben t assay (ELISA) as an indication of breeder vaccine success. The IBDV chall enge of progeny correlates more closely to performance than does ELISA. Fou r IBDV serologic and challenge studies were undertaken using progeny form i ntegrators to determine the efficacy of vaccination programs. All ;breeder received two live and two inactivated vaccines. For each experiment, day-ol d progeny were taken from six breeder flocks. At 2 wk, 15 progeny per flock were challenged with the serologic standard (STD) virus, 15 per flock with variant E, and 15 per flock with one of four variants (GA, ARK-1, ARK-2 an d MISS). Percent protection for the STD were close to the MISS and ARK-1 is olates, whereas percent protection for the ARK-2 and GA isolates was simila r to variant E. The new ELISA was improved over previous products and corre lated with resistance to challenge against the STD, MISS, and ARK-1, but no t with the other isolates. Therefore, producers must improved their vaccina tion programs or risk continued problems due to antigenic variants.