Novel variant infectious bursal disease virus diminishes FAdV-4 vaccination and enhances pathogenicity of FAdV-4.

Infectious bursal disease virus (IBDV) caused an acute and highly contagious infectious disease characterized by severe immunosuppression, causing considerable economic losses to the poultry industry globally. Although this disease was well-controlled under the widely use of commercial vaccines in the past decades, the novel variant IBDV strains emerged recently because of the highly immunized-selection pressure in the field, posting new threats to poultry industry. Here, we reported novel variant IBDV is responsible for a disease outbreak, and assessed the epidemic and pathogenicity of IBDV in this study. Moreover, we constructed a challenge model using Fowl adenovirus serotype 4 (FAdV-4) to study on the immunosuppressive effect. Our findings underscore the importance of IBDV surveillance, and provide evidence for understanding the pathogenicity of IBDV.