TABLE 3.

Cross-protective immunity elicited by PspA/EF3296 fragments in BALB/c mice

Immunogena and strainCapsular typePspA clade(s)bMedian no. of days to deathcP valueAlive/deadd ratioP value
NonimmuneImmuneNonimmuneImmune
SW111
    A66.131 + 2e220.4560:70:71.000
    BG73226B27210.0260:75:20.020
    3JYP2670344210.0260:75:20.020
    ATCC 6303353210.0180:76:10.005
HR101
    A66.131 + 25210.3603:56:40.630
    BG73226B24210.0430:75:50.044
    3JYP2670346210.0360:35:00.017
    ATCC 63033557.50.5152:64:60.640
HR107
    A66.131 + 2440.5611:104:80.310
    BG73226B2813.50.6213:85:70.660
    3JYP267034220.9200:40:51.000
    ATCC 6303353120.1362:96:60.190
HR108
    A66.131 + 24.530.1112:182:171.000
    BG73226B2921<0.0012:1314:3<0.001
    3JYP267034230.1102:156:120.230
    ATCC 630335321<0.0010:1711:6<0.001
  • a Mice were immunized and boosted 2 weeks apart with 1 μg of protein and challenged 2 weeks after the boost.

  • b Clades 1 and 2 are in family 1; clades 3, 4, and 5 are in family 2. For protection elicited by these fragments against family 2, clade 3 strain EF3296, see Table 2.

  • c Median numbers of days to death were compared between immune and nonimmune mice with the two-tailed Mann-Whitney U test (nonparametric, two-sample rank test). Boldface P values indicate statistically significant differences.

  • d Fisher's exact test was used to compare alive/dead ratios of immune and nonimmune mice in survival experiments. Boldface P values indicate significant differences.

  • e A66.1 expresses both clade 1 and clade 2 PspA proteins (10).