Figure 7.

Protective efficacy of the MDV A/AA/6/60 LAIVs: Four-to-six-week-old female C57BL/6 mice (n = 11) were infected i.n. with 1 × 10⁵ FFU of the WT MDV A/AA/6/60 LAIV (PA_WT⁺/NS1_WT⁺) or mutant MDV A/AA/6/60 LAIVs (PA_WT⁺/NS1_MT⁻, PA_MT⁻/NS1_WT⁺, PA_MT⁻/NS1_MT⁻), or PBS. At 21 days post-vaccination mice were challenged with 1000X MLD₅₀ of pH1N1. Body weight (A) and mortality (B) were monitored for 14 days (n = 5). At Days 2 and 4 post-challenge, mice were sacrificed (n = 3 per time point) and viral titers in the lungs of infected animals were determined by immunofocus assay using the anti-NP mAb HB-65 (C). Symbols represent data from individual mice. Bars represent the geometric mean for each group and the indicated virus was detected only in one or two mice. The dotted line represents the limit of detection (200 FFU/mL).