Interestingly, among the cells infected with the 4C(−), Cm2′, Cm*, and D80A viruses, numbers of GFP-fluorescent cells were also reduced dramatically by IFN-α treatment, but reduced remarkably even in the absence of IFN-α, suggesting that the infection itself was able to induce an antiviral state without IFN treatment, and that the charged amino acids substituted within the Cm2′, Cm*, and D80A viruses played important roles in this function. This evidence concerns the gene IFNA1 and infection.