For example, the expression of several genes that play crucial roles in the immune system, such as T-cell-specific surface glycoprotein CD28 (CD28), T-cell surface glycoprotein CD8 alpha chain (CD8A), T cell-specific protein-tyrosine kinase (LCK), zeta chain of T cell receptor associated protein kinase 70 (ZAP70), tyrosine-protein kinase BTK (BTK), B-cell receptor CD22 (CD22), CD79 alpha (CD79A), and perforin 1(PEF1), was significantly downregulated after infection. The gene discussed is BTK; the disease is infection.