Similarly, the significant infiltration of CD8+ T cells and macrophages, which led to the elevation of IFN-γ in NDV AF2240 infected chicken bursa caused higher magnitude of organ damage, failure of antibody production and higher mortality in chicken which suggested that the infection of NDV strain AF2240 was far more acute than the infection of NDV strain IBS002 [31]. This evidence concerns the gene IFNG and infection.