In research on the relationship between viral infections and asthma, it has been observed that in HDM-sensitized mice infected with H1N1, the levels of IL-4 and IL-5 in bronchoalveolar lavage fluid (BALF) significantly increase at multiple time points following infection, while the level of the Th1 inflammatory mediator IFN-γ decreases. The gene discussed is IL4; the disease is asthma.