Macrophages are the target cells of genotype VII Newcastle disease virus and promote the infection and apoptosis of chicken splenic T cells.

Infection with genotype VII Newcastle disease virus (NDV) poses a substantial threat to poultry health and is characterized by severe damage to immune organs, with effects such as lymphocyte depletion. However, the precise mechanisms underlying this phenomenon remain unclear. Our present investigation focused on the dynamic changes in macrophages, T cells, and B cells in the spleens of chickens infected with genotype VII NDV by using multicolour flow cytometry. We found that NDV selectively infected chicken splenic macrophages and significantly increased the number of macrophages at 4 days post-infection. In contrast, T and B cells became progressively depleted. In vitro experiments revealed that following genotype VII NDV infection, T cells underwent apoptosis more potently when they were cocultured with macrophages than when they were not. Overall, our findings highlight the changes in chicken splenic immune cell populations triggered by genotype VII NDV and illuminate the role of macrophages in T-cell depletion.