FIG 2.

Diagram of experimental mouse passages performed in this study with H1N1p (A), H3N2hu (B), and H3N2ca (C) or with H3N2ca in mouse-to-mouse lineages (C). Individual mice are displayed as control C57BL/6 (black) or CMAH^−/− (gray) mice within cohorts. The experiment was performed in two different iterations: series 1 proceeded for four passages among cohorts of four mice (two male, two female), while series 2 proceeded for three passages among cohorts of three mice (an alternating 2:1 sex ratio). H3N2ca mouse lung homogenates from passage 1 of series 2 were also used to initiate a series of mouse-to-mouse lineages in C57BL/6 (a, b, and c) or CMAH^−/− (d, e, and f) individual mice.