In the acute phase of infection (first 5 days post inoculation (p.i.)), the HEV-infected turkeys displayed a significant increase in the percentage of CD4+ cells and a decrease in the percentage of IgM+ B cells in blood (both P < 0.001), spleen (both P < 0.001) and CTs (P = 0.005 and P < 0.001, respectively), compared with the uninfected birds. The gene discussed is CD40LG; the disease is infection.