TABLE 2.

Protection of mice challenged with S. pneumoniae EF3296 by prior immunization with recombinant PspA/EF3296 fragments

Mice strain immunized and immunogena (amino acids)Median no. of days to deathbP valueAlive/deadc ratioP value
NonimmunedImmuneNonimmunedImmune
BALB/c
    SW111 (1-478)514.50.0360:105:50.032
    HR101 (1-115)321<0.0010:1514:7<0.001
    HR102 (75-305)550.5700:233:200.230
    HR104 (181-490)5210.0113:1311:50.011
    HR107 (75-490)590.0081:229:130.004
    HR108 (314-418)2.5210.0083:79:10.020
CBA/N
    SW111 (1-478)2210.0010:75:20.020
    HR101 (1-115)341.0000:70:71.000
    HR102 (75-305)59.50.0441:115:70.155
    HR107 (75-490)421<0.0011:910:0<0.001
    HR108 (314-418)2210.0150:85:30.026
  • a Mice were immunized and boosted 2 weeks apart with 1 μg of protein and challenged 2 weeks after the boost with 2 × 106 EF3296 bacteria.

  • b Median numbers of days to death were compared with the two-tailed Mann-Whitney U test (nonparametric, two-sample rank). Boldface P values indicate significant differences from the control value.

  • c Fisher's Exact test was used to compare alive/dead ratios in survival experiments. Boldface P values indicate significant differences obtained from the control value.

  • d There is no reason to expect that the results obtained with the nonimmune mice would not have been the same for each mouse strain. The slight differences in frequency of survivors for the different control groups are not significant. Even so, these groups were not pooled prior to analysis.