TABLE 3.
Proportions of plasma sample with positive levels of non-PAM type VSA-specific and VSAPAM-specific antibodies
| Immunoglobulin | Negative cutoff value (MFI)a | Proportion
|
||||
|---|---|---|---|---|---|---|
| Yaounde
|
Etoa (pregnant) (C) | Statistical significance (χ2 test)
|
||||
| Nonpregnant (A) | Pregnant (B) | P (A vs B) | P (B vs C) | |||
| Non-PAM type VSA | ||||||
| IgG | 31.62 | 0.93 (0.84-0.97)b | 0.90 (0.85-0.93) | 1.00 (0.89-1.00) | 0.65 | 0.13 |
| IgG1 | 35.35 | 0.88 (0.79-0.94) | 0.95 (0.91-0.97) | 1.00 (0.89-1.00) | 0.09 | 0.45 |
| IgG2 | 39.71 | 0.13 (0.07-0.23) | 0.18 (0.13-0.24) | 0.23 (0.11-0.40) | 0.51 | 0.69 |
| IgG3 | 34.90 | 0.66 (0.54-0.76) | 0.71 (0.64-0.77) | 0.77 (0.60-0.89) | 0.56 | 0.60 |
| IgG4 | 37.17 | 0.06 (0.02-0.14) | 0.11 (0.07-0.16) | 0.07 (0.02-0.21) | 0.35 | 0.68 |
| VSAPAM | ||||||
| IgG | 44.50 | 0.12 (0.06-0.22) | 0.29 (0.23-0.36) | 0.77 (0.60-0.89) | 0.008 | <0.001 |
| IgG1 | 49.66 | 0.12 (0.06-0.22) | 0.35 (0.29-0.42) | 0.94 (0.79-0.98) | <0.001 | <0.001 |
| IgG2 | 42.28 | 0.03 (0.01-0.10) | 0.08 (0.05-0.12) | 0.19 (0.09-0.36) | 0.30 | 0.08 |
| IgG3 | 41.44 | 0.04 (0.02-0.12) | 0.19 (0.14-0.25) | 0.52 (0.35-0.68) | 0.008 | <0.001 |
| IgG4 | 47.06 | 0.03 (0.01-0.10) | 0.01 (0.00-0.03) | 0.00 (0.00-0.02) | 0.36 | 0.31 |
a
Levels were considered positive if they exceeded subclass-specific negative cutoff values calculated from results obtained with unexposed control donors (donors without exposure to any P. falciparum parasites for non-PAM type VSA and nulligravidae from Yaounde for VSAPAM). See Materials and Methods for details.
b
The values in parentheses are 95% confidence interval.