In this study, at both 14 dpv and 28 dpv, the levels of IL-2, IL-4, and IL-6 in the PAD-S1-HN group and the commercial QX-NDV group were significantly greater (p < 0.01) than those in the PAD and PBS control groups were (Figure 3A, B, C). Here, IL2 is linked to peripheral arterial disease.