Geometric mean titers of S. flexneri 2a (Sfl2a) LPS specific IgG and IgA serum, ALS and SBA titers over time and their within-group comparisons (P values) at each post-vaccination visit compared to baseline

Immune response and sample dayVaccination group
Flexyn2a (n = 12)Flexyn2a + alum (n = 12)Placebo (n = 5)a
GMTResponderscP valuedGMTRespondersP valueGMTResponders
Anti-Sfl2a LPS Serum IgG
    Day 02,397NS1,600NSe2,111
    Day 2845,61411/12<0.000128,73512/12<0.00011,8380/5
    Day 5640,63711/12<0.000134,17212/12<0.00012,1110/5
Anti-Sfl2a LPS Serum IgA
    Day 0252NS267NS303
    Day 285,08011/120.00023,80511/120.00154000/5
    Day 564,52511/120.00024,27112/120.00023480/5
Anti-Sfl2a LPS ALS IgG
    Day 01NS1NS1
    Day 74812/12<0.00013010/120.000110/4b
    Day 2811/12NS10/12NS10/5
    Day 3557/12NS810/12NS10/5
Anti-Sfl2a LPS ALS IgA
    Day 01NS1NS1
    Day 7178/120.0011912/120.000510/4
    Day 2810/12NS10/12NS10/5
    Day 3522/12NS35/12NS11/5
Serum bactericidal assay
    Day 029NS50NS201
    Day 283918/12NS11889/12NS1450/5
    Day 5681710/120.0298143010/120.0027510/5
  • a Six subjects enrolled in the study. One subject dropped out post-first vaccination and was not included in the immunological analysis.

  • b One subject was unable to comply at the day 7 visit.

  • c “Responder” was defined as those with a 4-fold increase over baseline for serum and ALS responses and a 9-fold increase over baseline for bactericidal responses.

  • d P values were determined using a two-way ANOVA with a Bonferroni multiple comparison posttest (α = 0.05) of log-transformed titers in comparison to placebos at the same time point.

  • e NS, not significant.