FIG 3.

B-H1 priming increases mouse survival following H5N1 challenge. Mice were primed with B-H1, B-H3, or B/Yamagata/16/88 (wild-type) virus or administered PBS (n = 60/group). At 90, 180, 270, or 360 days after priming, mice were infected with H5N1 A/Vietnam/1203/04 (PR8 reassortant) virus at five different doses (10¹, 10², 10³, 10⁴, or 10⁵ PFU/mouse, n = 3 mice per dose). (A) Survival monitoring was performed daily for 14 days. Mice were euthanized when weight loss exceeded 25% of initial weight. (B) The 50% lethal dose (LD₅₀) for every group of primed mice at every time point was calculated. Every symbol in the graph represents a single LD₅₀ value.