Figure 2.
Effect of vaccination on bacterial clearance following coinfection with influenza virus and pneumococcus. Mice were immunized intramuscularly with 1 µg pneumococcal polysaccharide-conjugate vaccine and boosted 3 weeks later. Two weeks after that, all mice received 10 plaque-forming units of PR8 influenza virus or phosphate-buffered saline (PBS), and 10 days later, were challenged intranasally with 106 colony-forming units (CFUs)/mouse of A66.1 S. pneumoniae (serotype 3). Bacterial burdens in total lungs were determined 48 hours after pneumococcal infection. Each symbol represents an individual mouse (4 mice/group). The data represent results from at least 2 independent experiments. **P < .01. Abbreviations: naive PBS pneumo, unimmunized mice challenged with pneumococcus only; NS, not significant; vacc FLU pneumo, immunized mice coinfected with influenza and pneumococcus.