Carnitine plays a crucial role in fat metabolism and energy production in mammals, and it can support the production of CD4+ and CD8+ T cells during infection (81, 82); a prior study has shown that the levels of carnitine and several acylcarnitines were elevated in S. japonicum-infected Microtus fortis (M. fortis) and C57BL/6 mice, but the phenomenon was more obvious in M. fortis (21). The gene discussed is CD4; the disease is infection.