The potential of IBDV attenuated live vaccine against novel variant strain

Abstract Infectious bursal disease virus (IBDV) caused an acute and highly contagious infectious disease characterized by and severe immunosuppression, causing great economic losses to the poultry industry globally. Over the past 30 years, this disease has been well controlled based on the scientific strategy of vaccination and the strict biosafety measures. However, the novel variant IBDV strain emerged in recent years, posting a new threat to the poultry industry. Few novel variant IBDV strain was isolated from 2512-immunized chickens in our previous epidemiological survey, providing clues that the attenuated live vaccines maybe efficacious against the novel variant strains. Here, we reported the protective effect of the attenuated live vaccine (2512 strain) against novel variant strain in SPF chickens and commercial yellow-feathered broilers. We found that 2512 causes severe atrophy of the bursa of Fabricius in SPF chickens and commercial yellow-feathered broilers, that 2512 induces high levels of antibodies against IBDV, and that 2512 limits viral growth of the novel variant strains via placeholder effect. This study highlighted the protective effect of commercial attenuated live vaccines against the novel variant IBDV, and pro-vide guidance for the prevent and control of this disease.