TABLE 2.

Protective effectsa of combinations of high-titer antibody responses

AntigenMain effects and interactionbCombination effectc
Risk ratio (95% CI)dP valueRisk ratio (95% CI)dP value
AMA1_3D70.59 (0.32-1.08)0.0910.21 (0.05-0.88)0.033*
MSP-3_K10.56 (0.29-1.08)0.085
AMA1_3D7 + MSP-3_K10.28 (0.06-1.29)0.104
AMA1_3D70.66 (0.35-1.25)0.2110.24 (0.09-0.64)0.004*
MSP-2_Dd20.40 (0.20-0.78)0.008*
AMA1_3D7 + MSP-2_Dd20.33 (0.09-1.17)0.087
AMA1_3D70.62 (0.32-1.18)0.1470.61 (0.29-1.29)0.199
EBA-175_F2_3D70.69 (0.33-1.42)0.320
AMA1_3D7 + EBA-175_F2_3D71.90 (0.34-10.46)0.459
AMA1_3D70.58 (0.31-1.08)0.0880.48 (0.17-1.38)0.178
MSP-1191.44 (0.82-2.54)0.199
AMA1_3D7 + MSP-1190.39 (0.12-1.30)0.129
MSP-2_Dd20.40 (0.20-0.78)0.008*Total protection (n = 33)
MSP-3_K10.62 (0.34-1.13)0.121
MSP-2_Dd2 + MSP-3_K1Total protection (n = 33)
MSP-2_Dd20.38 (0.20-0.73)0.004*0.17 (0.04-0.73)0.017*
EBA-175_F2_3D70.64 (0.33-1.22)0.178
MSP-2_Dd2 + EBA-175_F2_3D70.26 (0.05-1.27)0.098
MSP-2_Dd20.36 (0.18-0.71)0.003*0.52 (0.21-1.30)0.166
MSP-1191.55 (0.92-2.61)0.097
MSP-2_Dd2 + MSP-1190.62 (0.20-1.88)0.402
MSP-3_K10.57 (0.29-1.11)0.1010.39 (0.12-1.20)0.103
EBA-175_F2_3D70.66 (0.33-1.31)0.240
MSP-3_K1 + EBA-175_F2_3D70.71 (0.17-2.97)0.643
MSP-3_K10.48 (0.25-0.93)0.030*0.57 (0.25-1.31)0.191
MSP-1191.74 (1.07-2.84)0.024
MSP-3_K1 + MSP-1190.65 (0.19-2.27)0.509
EBA-175_F2_3D70.56 (0.28-1.11)0.1010.69 (0.26-1.78)0.445
MSP-1191.61 (0.97-2.68)0.062
EBA-175_F2_3D7 + MSP-1190.70 (0.19-2.52)0.586
AMA1_3D70.55 (0.30-1.01)0.0550.66 (0.29-1.52)0.336
MSP-1_B20.87 (0.51-1.50)0.636
AMA1_3D7 + MSP-1_B21.13 (0.36-3.56)0.829
MSP-2_Dd20.36 (0.18-0.70)0.008*0.40 (0.15-1.05)0.064
MSP-1_B21.04 (0.62-1.72)0.875
MSP-2_Dd2 + MSP-1_B20.57 (0.17-1.90)0.365
MSP-3_K10.52 (0.27-1.02)0.0590.16 (0.02-1.13)0.067
MSP-1_B20.87 (0.51-1.49)0.634
MSP-3_K1 + MSP-1_B20.15 (0.02-1.14)0.068
MSP-1191.61 (0.95-2.74)0.0730.98 (0.48-2.01)0.972
MSP-1_B20.80 (0.45-1.41)0.456
MSP-119 + MSP-1_B20.83 (0.27-2.46)0.737
EBA-175_F2_3D70.58 (0.30-1.14)0.1190.85 (0.36-2.00)0.720
MSP-1_B20.88 (0.51-1.51)0.656
EBA-175_F2_3D7 + MSP-1_B22.11 (0.56-7.94)0.265
  • a Risk of developing clinical malaria associated with combinations of high titers compared to low/undetectable titers of antibodies to individual antigens in a subset of the Chonyi cohort (n = 119). In the majority of cases, significantly more protection was obtained with high-level antibody responses to pairs of antigens, compared to single antigens (Table 1). No strong evidence of statistical interaction between pairs of antibodies was observed.

  • b The main effects of antibodies to each antigen were adjusted for each other. Interaction effects (combinations of two antigens) are those over and above the main effects.

  • c Effects of combinations of high-titer responses (combines the main effects and interaction effects).

  • d Risk ratios (with 95% confidence intervals [CI]) are from multivariate analyses (adjusted for both age and reactivity to P. falciparum schizont extract). *, P < 0.05.