During mastitis in dairy cows, the body will generate an immune response to resist the interference of external unfavorable factors, and Sphingomonas from Proteobacteria participates in the immune regulation of the body, which can reduce the maturation ability of participating effector CD8+T cells (also referred as killer T cells), thus hindering the construction of CD8+ anti-tumor cytotoxic T cells [24]. The gene discussed is CD8A; the disease is mastitis.