Macrophages are the target cells for 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 significant threat to poultry health, characterized by severe damage to immune organs such as lymphocyte depletion. However, the precise mechanisms underlying this phenomenon remain unclear. Our present investigation focused on the dynamic changes of macrophages, T cells, and B cells in the spleen of chickens infected with genotype VII NDV by using multicolor 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 experiment revealed that following genotype VII NDV infection, T cells underwent apoptosis more potently when co-cultured with macrophages than that without macrophages. 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.