As shown in Figure 7A, in the Exo-M5-IFITM3 group, the spleen index showed a significant increase compared with the Exo-M5-siIFITM3 group at 3 weeks of infection but was still lower than that of the PBS control group at 1, 3, and 5 weeks of infection (p < 0.05). Here, IFITM3 is linked to infection.