Field study using sentinel birds and ELISA for differentiating infected from vaccinated animals (DIVA) in chicken flocks vaccinated with inactivated avian influenza H5 vaccines

in the majority of tested birds while noninfected sentinels showed negative results.3. Broiler flocks exposed to H5N1 infection (F3, F6 and F7) showed positive ELISA titres (at least 75%), while, noninfected broiler flocks showed negative results. This indicated that, even without using sentinels, ELISA kits for AIV M and NP could be used as a DIVA tool. However, flocks vaccinated with H5 inactivated whole virus vaccines showed negative ELISA titres at 30 d old after single vaccination, while after booster dose(s), positive ELISA titres were observed.4. The trial demonstrated the unsuitability of ELISA kits for influenza A as DIVA tool in flocks vaccinated several times like layer and breeder flocks. However, sentinel birds could be considered as possible DIVA strategy for longer-lived birds, such as layer and breeder flocks.