Fig. (4) GBS clearance from mouse lungs 2 and 24 hours post infection (h.p.i.) with 10⁷ CFU of GBS (type II). Groups of immunized mice (5 in group) were infected with 500 MID₅₀ of A(H7N3)-wt or 100 MID₅₀ of A/PR8/34 and coinfected with 10⁷ CFU of GBS (type II) 24 hours later. GBS was isolated from the lungs on 2, 24 and 48 hours after bacterial infection. P-values indicate differences in bacterial titers between 2 h.p.i. and 24 h.p.i. timepoints.