FIG 9.

BF1-19 provides 100% protection against challenge from A/Vietnam/1203/04 (H5N1) in vitro escape mutants. BF1-19 escape mutants were generated using a virus based on A/Puerto Rico/8/34, generated by reverse genetics, containing the hemagglutinin and neuraminidase genes from A/Vietnam/1203/04 (H5N1). Mice were administered 10⁶ TCID₅₀s of the S145F or K144N escape mutant (in hemagglutinin) intranasally, followed by a single 2.5-mg/ml intraperitoneal dose of BF1-19 administered at 24 h postchallenge. All mice that received BF1-19 survived the challenge, while 80% of mice that did not receive antibody died (A and B). (A) Data represent the mean percentage of the starting weight ± standard error of the mean for each mouse group (n = 5 mice per group). **, P < 0.01.