In RV-infected piglets, lactose administration significantly relieved the negative influence of rotavirus infection on the sIgA level of jejunal mucosa; the IL-2, IL-4, pBD1, and pBD3 mRNA expression of jejunal mucosa and/or mesenteric lymph nodes; and further promoted the IFN-γ and IFN-β mRNA expression of jejunal mucosa and/or mesenteric lymph nodes (p < 0.05, Table 6 and Table 10). The gene discussed is IL4; the disease is Rotavirus infection.