It is noteworthy that IL-22 secretion in the mucosal NKp44+ NK cells increased dramatically with virus infection, from 5.58% (0 dpi) to 24.50% (9 dpi) in the Peyer's patches and from 3.78% (0 dpi) to 54.20% (9 dpi) in the lamina propria (Figure 6(b)). This evidence concerns the gene NCR2 and viral infectious disease.