CD4 and infection: Seventy-two hours after G. parasuis challenge, there was a decrease in the proportions of CD3+ T cells, CD3+CD4+ T cells, and CD3+CD8+ T cells among splenocytes in the infection group compared to those in the control group (P < 0.001); levamisole, BMS-1 and 50 and 100 mg/kg baicalin improved the proportions of CD3+ T cells, CD3+CD4+ T cells and CD3+CD8+ T cells in the infection group (P < 0.05; Figure 4A, Additional file 2, panels A1–A7; Figure 5B, Additional file 3, panels A1–A7; Figure 6A, Additional file 4, panels A1–A7).