Plant-based vaccine against Infectious bursal disease. An alternative to inactivated vaccines for breeder pullets

LUCERO, S.; RICHETTA, M.; CHIMENO ZOTH, S.; CANET, Z.; BERINSTEIN, A.; GÓMEZ, E.

Congreso; XV Avian Immunology Research Group (AIRG) Meeting; 2018

Infectious bursal disease virus is the etiological agent of an immunosuppressive and highly contagious disease that affects young birds causing important economic losses in the poultry industry. Usually, the disease is controlled by strict hygiene management and effective vaccination programs. These include hyperimmunization of breeder pullets with inactivated vaccines before the laying period in order to supply maternal antibodies against IBDV to the progeny. However, thesevaccines are costly due to the treatment processes involved in inactivating the virus and require strict quality control to ensure that killed organisms are fully inactivated and harmless. The capsid protein VP2 which contains the major neutralizing epitopes has been expressed in a variety of heterologous system for the development of safer and potentially cheaper subunit vaccines. The objective of this work was to assess the efficacy of a plant-based vaccine candidate for pulletsthrough the study of maternally derived antibody (MDA) levels and kinetics in the progeny. For this purpose, 16 weeks old pullets which had received two doses of live attenuated vaccine according to traditional vaccination programs were randomly divided in 3 groups. Two groups were immunized intramuscularly with the recombinant immunogen containing 30 µg of VP2 or with commercial inactivated vaccine, while negative control group did not receive any boost. Pullets were bled prior to and 3, 9 and 28 weeks after immunization. Offspring from each group were weekly bled to study passive immunity. Both, subunit vaccine candidate and inactivated vaccine, were able to boost specific antibody levels in pullets. Moreover, MDA titles and their persistence in the progeny were indistinguishable in these two groups while lower antibody titles which decayed rapidly wereobserved in control group. These results demonstrate that our immunogen could be a viable alternative to inactivated vaccines given to breeder pullets