Fig. 4.
Protection against intranasal infection by a lethal dose of PR8 influenza virus in mice immunized with inactivated PR8 or PR8αgal virus. A. Survival of mice immunized twice with 1 μg inactivated PR8 vaccine (○) in GT-KO mice; PR8αgal (●) vaccine in GT-KO mice; or with PR8αgal (△) vaccine in wild-type mice. The mice were challenged with 2000 PFU of live PR8 in 50 μl (n = 25 per group). Survival data are presented as % of live mice at various days following the challenge. Survival results on Day 30 were similar to those on Day 15 post challenge. B. PR8 virus titers in lungs of GT-KO mice, 3 days after challenge with live virus. The virus titers were assayed in supernatants of lung homogenates from the immunized mice, by hemagglutination of chicken red blood cells (n = 5 per group). Modified from [28].