Given the different functions of type I IFN vs IFN-λ in HMPV infection, we next tested whether this correlated to differences in lung innate immune cell recruitment by flow cytometry of lung cells in mock- vs HMPV-infected WT, Ifnar1−/−, and Ifnlr1−/− mice early post-infection. The gene discussed is IFNLR1; the disease is infection.