The populations of KUL1<sup>+</sup>, CD3<sup>+</sup>CD4<sup>+</sup> and CD3<sup>+</sup>CD8<sup>+</sup> cells were significantly increased in both types of chickens at 3 dpi, and there was significant early depletion of IgM<sup>+</sup> B cells at 1 dpi in the red jungle fowl. vvIBDV infection also induced differential expression of genes that are involved in Th1 and pro-inflammatory responses, with groups receiving the higher dose (10<sup>6.8</sup> EID<sub>50</sub>) showing earlier expression of IFNG, IL12B, IL15, IL6, CXCLi2, IL28B, and TLR3 at 1 dpi.
Our results suggest that NK cell activity may be therapeutically enhanced by administering IL-15 and IL-18 in virus infections that inadequately activate NK cells.<b>IMPORTANCE</b> In infections with retroviruses, like HIV and FV infection of mice, NK cells clearly mediate antiviral activities, but they are usually not sufficient to prevent severe pathology.
Importantly, these data demonstrate novel T cell interleukin-15 expression and indicate a plausible regulatory mechanism for this cell-type during viral infection.
IL-15, a promising cytokine for treating cancer and viral diseases, is presented in trans by the IL-15 receptor (IL-15R) alpha-chain to the IL-15Rβγc complex displayed on the surface of T cells and natural killer (NK) cells.