Evaluation of modified vaccinia virus Ankara expressing VP2 protein of infectious bursal disease virus as an immunogen in chickens

A recombinant modified vaccinia Ankara (MVA) virus expressing mature viral protein 2 (VP2) of the infectious bursal disease virus (IBDV) was constructed to develop MVA-based vaccines for poultry. We demonstrated that this recombinant virus was able to induce a specific immune response by observing the production of anti-IBDV-seroneutralizing antibodies in specific pathogen-free chickens. Besides, as the epitopes of VP2 responsible to induce IBDV-neutralizing antibodies are discontinuous, our results suggest that VP2 protein expressed from MVA-VP2 maintained the correct conformational structure. To our knowledge, this is the first report on the usefulness of MVA-based vectors for developing recombinant vaccines for poultry.

[ impact of the routes of live vaccine administration against infectious bursal disease on mounting antibody response in broiler chickens]

Infectious bursal disease [IBD] is one of the most important viral poultry diseases. To prevent the disease it is required that there be maternal and active immunity prior to and after three weeks of age. Live vaccines are usually used to immunize the broiler flocks. In addition to the type of vaccine, the route of vaccination, also, has effects on mounting an immune response. In this study, we administered a single dose vaccination of an intermediate IBD vaccine strain at 21 days of age via five routes including subcutaneous [SC], intramuscular [IM], drinking water, eye drop, and course spray. The impact of the vaccination route on mounting antibody response was evaluated by a commercial ELISA kit [IDEXX]. Antibody response was mounted by all routes. The highest antibody titer in the last two sampling turns belonged to birds in the group vaccinated by the SC route, but this difference was not statistically significant [p>0.05] when compared to those of other vaccinated groups. In addition to the highest antibody titer, the highest bursal/body weight ratio and body weight were observed in birds of the SC-vaccinated group. It was found that the groups vaccinated by injection, SC or IM, were the only groups that achieved to a protective level of antibody titer in the last turn of sampling. It was concluded that a single dose injection of an intermediate IBD vaccine, via SC route, is able to induce higher antibody response, and improve bursal health and performance of chickens as compared with those vaccinated via drinking water