Fig 5.
Virulence of PspA+ and PspA− pneumococci in mice. Virulence was monitored by comparing the survival time of mice infected with wild-type and mutant strains of S. pneumoniae. (A) WU2, BR260.1, JY1119, A66.1, or BR240.1 (200 CFU) was used to infect CBA/N mice. (B) A66.1 or BR240.1 (1 × 104 CFU) was used to infect BALB/cByJ mice. The survival times of mouse groups infected with mutant strains were compared to those of mouse groups infected with wild-type strains. (C) A66.1 or BR240.1 (2 × 105 CFU) was injected i.v. into groups of 4 to 5 BALB/cByJ mice. Mouse blood samples were collected from the retro-orbital plexus at the indicated time points. Samples were serially diluted and plated on blood agar to determine the numbers of viable bacteria (CFU) in the blood. (*, P < 0.05; **, P < 0.002).