To analyze whether the viruses isolated from MxAtg/−Rag2−/− mice show increased MxA resistance in vivo, the viruses isolated at days 11, 13, and 16 post-infection (d11, d13, d16; Figure 2C) were used to infect MxAtg/tg mice with 104 PFU (n = 3 for each virus; Figure 3A). This evidence concerns the gene MX1 and infection.