Background
Methods
Ethical consideration
Study design and plasma samples
Diagnosis of placental malaria and anaemia
Recombinant proteins
Coupling of recombinant proteins to SeroMAP microspheres
Measuring IgG using a multi-analyte platform assay
IgG subclass determination to the FV2
Avidity to the FV2
Determining the breadth of the VAR2CSA antibody response
Statistical analysis
Results
Characteristics of study population
Characteristica
| PM positive (n = 96) | PM negative (n = 324) | p value |
---|---|---|---|
Age in years (mean ± SD) | 27.6 ± 4.6 | 29.4 ± 5.6 |
0.0012
|
Gravidity (mean ± SD) | 4.5 ± 1.6 | 5.2 ± 2.0 |
0.0002
|
Prevalence of women with peripheral malaria by blood smears, n (%) | 68 (70.8 %) | 5 (1.5 %) |
<0.0001
|
Peripheral malaria parasitaemia among all women, parasites/µL (mean ± SD) | 0.2 ± 0.6 | 0.0 ± 0.02 |
0.0011
|
Peripheral malaria parasitaemia among blood smear positive women parasites/µL (mean ± SD) | 0.3 ± 0.7 | 0.1 ± 0.5 | 0.12 |
Prevalence of women with placental parasitaemia, n (%) | 96 (100 %) | 0 (0 %) | |
Placental parasitaemia by impression smears, (%) (mean ± SD) | 3.5 ± 7.6 | 0 ± 0 | |
Pre-term deliveries, n (%) | 16 (16.7 %) | 63 (19.4 %) | 0.59 |
Length of pregnancy in weeks (mean ± SD) | 39.1 ± 2.7 | 39.1 ± 3.0 | 0.95 |
Full-term deliveries | 39.9 ± 1.7 | 40.3 ± 1.5 | 0.12 |
Pre-term deliveries | 34.3 ± 1.7 | 34.0 ± 2.4 | 0.50 |
Intra-uterine growth restriction, n (%) | 2 (2.1 %) | 9 (2.8 %) | 0.99 |
Maternal anaemia at delivery, n (%) | 24 (25.0 %) | 39 (12.0 %) |
0.0055
|
Haematocrit in % (mean ± SD) | 32.0 ± 5.0 | 34.7 ± 5.1 |
<0.0001
|
Low birth weight babies, n (%) | 11 (11.5 %) | 30 (9.3 %) | 0.68 |
Among full-term deliveries | 2 (2.5 %) | 8 (3.2 %) | 1.00 |
Among pre-term deliveries | 8 (53.3 %) | 20 (33.9 %) | 0.30 |
Neonate weight in grams (mean ± SD) | 3139 ± 600 | 3257 ± 611 | 0.10 |
Full-term deliveries | 3303 ± 433 | 3393 ± 478 | 0.13 |
Pre-term deliveries | 2337 ± 667 | 2681 ± 739 | 0.10 |
Differences in immune responses to VAR2CSA between multigravidae with and without PM
Antibody responsea
| PM positive (n = 96) | PM negative (n = 324) | p value |
---|---|---|---|
DBL1 3D7 (Pichia pastoris) (mean ± SD) | 4832 ± 4487 | 4569 ± 4031 | 0.61 |
DBL1 7G8 (Pichia pastoris) (mean ± SD) | 6479 ± 4095 | 6558 ± 4237 | 0.70 |
DBL1 + 2 FCR3 (Baculovirus) (mean ± SD) | 8582 ± 6649 | 7901 ± 5996 | 0.37 |
DBL2 FCR3 (Baculovirus) (mean ± SD) | 2416 ± 2709 | 2622 ± 3041 | 0.53 |
DBL3 FCR3 (Baculovirus) (mean ± SD) | 6917 ± 5052 | 7524 ± 5675 | 0.32 |
DBL3 7G8 (Pichia pastoris) (mean ± SD) | 9940 ± 6437 | 10,986 ± 6661 | 0.17 |
DBL3 FCR3 (Escherichia coli) (mean ± SD) | 7535 ± 5542 | 8171 ± 5977 | 0.34 |
DBL4 FCR3 (Baculovirus) (mean ± SD) | 7966 ± 4666 | 8130 ± 5481 | 0.78 |
DBL4 7G8 (Pichia pastoris) (mean ± SD) | 4476 ± 4130 | 4594 ± 4510 | 0.73 |
DBL4 FCR3/IT4 (Pichia pastoris) (mean ± SD) | 6274 ± 4333 | 5296 ± 4428 | 0.056 |
DBL5 FCR3 (Baculovirus) (mean ± SD) | 15,749 ± 6804 | 15,270 ± 6213 | 0.54 |
DBL5 3D7 (Pichia pastoris) (mean ± SD) | 13,237 ± 5857 | 12,124 ± 5727 | 0.11 |
DBL5 7G8 (Pichia pastoris) (mean ± SD) | 13,043 ± 5563 | 12,403 ± 5524 | 0.33 |
DBL6 FCR3 (Baculovirus) (mean ± SD) | 7,655 ± 5726 | 8078 ± 6287 | 0.54 |
DBL6 7G8 (Pichia pastoris) (mean ± SD) | 7,293 ± 4953 | 7459 ± 4486 | 0.77 |
DBL6 FCR3/IT4 (Pichia pastoris) (mean ± SD) | 4,364 ± 3473 | 4609 ± 3577 | 0.55 |
FV2 FCR3 (Baculovirus) (mean ± SD) | 11,280 ± 5293 | 11,475 ± 5654 | 0.76 |
Per cent high avidity to FV2 (mean ± SD) | 29.3 ± 12.4 | 33.7 ± 12.6 |
0.0030
|
Per cent of women with ≥35 % high avidity Ab (%) | 37.5 % | 46.9 % | 0.11 |
Number of domains recognized out of 6 (mean ± SD) | 4.2 ± 1.3 | 4.1 ± 1.3 | 0.65 |
Number of variants recognized out of 15 (mean ± SD) | 9.3 ± 3.7 | 9.1 ± 3.6 | 0.67 |
CSP (mean ± SD) | 920 ± 1030 | 974 ± 1066 | 0.66 |
RESA (mean ± SD) | 1033 ± 2094 | 1047 ± 1861 | 0.96 |
AMA-1 3D7 (mean ± SD) | 14,814 ± 4477 | 12,004 ± 5083 |
<0.0001
|
MSP1 3D7 (mean ± SD) | 9051 ± 6976 | 7360 ± 6246 |
0.035
|
MSP2 3D7 (mean ± SD) | 16,224 ± 8444 | 13,224 ± 8658 |
0.0028
|
Association between Ab to VAR2CSA and absence of PM
Increment unit | Unadjusted | Adjusteda
| Adjustedb
| ||||
---|---|---|---|---|---|---|---|
OR (95 % CI) | p value | OR (95 % CI) | p value | OR (95 % CI) | p value | ||
Immune responses to VAR2CSA | |||||||
DBL1 3D7 (Pichia pastoris) | 5147.5 | 0.93 (0.70, 1.22) | 0.59 | 0.90 (0.67, 1.20) | 0.47 | 0.91 (0.68, 1.21) | 0.51 |
DBL1 7G8 (Pichia pastoris) | 5543.8 | 0.94 (0.70, 1.27) | 0.70 | 0.95 (0.70, 1.28) | 0.73 | 0.95 (0.70, 1.29) | 0.75 |
DBL1 + 2 FCR3 (Baculovirus) | 9077.3 | 0.85 (0.61, 1.19) | 0.35 | 0.87 (0.62, 1.22) | 0.43 | 0.88 (0.63, 1.23) | 0.46 |
DBL2 FCR3 (Baculovirus) | 2087.0 | 1.05 (0.89, 1.25) | 0.55 | 1.07 (0.90, 1.27) | 0.48 | 1.08 (0.90, 1.29) | 0.40 |
DBL3 FCR3 (Baculovirus) | 8125.0 | 1.18 (0.84, 1.67) | 0.89 | 1.22 (0.86, 1.72) | 0.27 | 1.23 (0.87, 1.75) | 0.25 |
DBL3 7G8 (Pichia pastoris) | 11,573.0 | 1.33 (0.88, 1.99) | 0.18 | 1.28 (0.85, 1.93) | 0.24 | 1.27 (0.85, 1.92) | 0.25 |
DBL3 FCR3 (Escherichia coli) | 9346.8 | 1.19 (0.82, 1.73) | 0.36 | 1.16 (0.80, 1.68) | 0.44 | 1.15 (0.79, 1.67) | 0.46 |
DBL4 FCR3 (Baculovirus) | 7023.0 | 1.04 (0.77, 1.41) | 0.79 | 1.06 (0.78, 1.44) | 0.73 | 1.07 (0.78, 1.46) | 0.68 |
DBL4 7G8 (Pichia pastoris) | 5244.3 | 0.96 (0.73, 1.25) | 0.74 | 0.95 (0.72, 1.24) | 0.69 | 0.94 (0.72, 1.24) | 0.68 |
DBL4 FCR3/IT4 (Pichia pastoris) | 5088.3 | 0.79 (0.61, 1.01) | 0.059 | 0.80 (0.62, 1.03) | 0.080 | 0.80 (0.63, 1.03) | 0.086 |
DBL5 FCR3 (Baculovirus) | 11,083.0 | 0.88 (0.59, 1.31) | 0.52 | 0.88 (0.59, 1.32) | 0.54 | 0.87 (0.58, 1.30) | 0.49 |
DBL5 3D7 (Pichia pastoris) | 9502.3 | 0.72 (0.49, 1.06) | 0.098 | 0.72 (0.49, 1.06) | 0.097 | 0.71 (0.48, 1.04) | 0.079 |
DBL5 7G8 (Pichia pastoris) | 9335.5 | 0.82 (0.55, 1.21) | 0.32 | 0.81 (0.55, 1.21) | 0.31 | 0.80 (0.54, 1.19) | 0.27 |
DBL6 FCR3 (Baculovirus) | 9534.0 | 1.11 (0.78, 1.60) | 0.56 | 1.09 (0.76, 1.56) | 0.66 | 1.09 (0.76, 1.56) | 0.66 |
DBL6 7G8 (Pichia pastoris) | 6554.5 | 1.05 (0.76, 1.46) | 0.76 | 1.08 (0.78, 1.50) | 0.66 | 1.05 (0.76, 1.47) | 0.76 |
DBL6 FCR3/IT4 (Pichia pastoris) | 3803.5 | 1.08 (0.84, 1.39) | 0.56 | 1.05 (0.82, 1.36) | 0.69 | 1.05 (0.82, 1.35) | 0.72 |
FV2 FCR3 (Baculovirus) | 9579.5 | 1.06 (0.72, 1.57) | 0.77 | 1.06 (0.71, 1.57) | 0.80 | 1.05 (0.71, 1.57) | 0.81 |
Per cent high avidity to FV2 | 1 | 1.03 (1.01, 1.05) |
0.0033
| 1.03 (1.01, 1.05) |
0.0079
| 1.03 (1.01, 1.04) |
0.010
|
Per cent of women with ≥35 % high avidity Ab to FV2 | 1 | 1.47 (0.92, 2.35) | 0.11 | 1.45 (0.90, 2.32) | 0.13 | 1.43 (0.89, 2.30) | 0.15 |
Number of domains recognized out of 6 | 1 | 0.96 (0.81, 1.14) | 0.65 | 0.96 (0.81, 1.15) | 0.67 | 0.96 (0.81, 1.15) | 0.68 |
Number of variants recognized out of 15 | 1 | 0.99 (0.93, 1.05) | 0.67 | 0.98 (0.92, 1.05) | 0.56 | 0.98 (0.92, 1.05) | 0.58 |
Immune responses to non-pregnancy associated antigens | |||||||
CSP | 875.5 | 1.05 (0.86, 0.27) | 0.66 | 1.00 (0.82, 1.22) | 1.00 | 1.01 (0.83, 1.24) | 0.93 |
RESA | 512.5 | 1.02 (0.94, 1.07) | 0.95 | 1.00 (0.94, 1.06) | 0.90 | 1.00 (0.94, 1.06) | 0.90 |
AMA-1 3D7 | 7905.8 | 0.36 (0.23, 0.56) |
<0.0001
| 0.37 (0.24, 0.58) |
<0.0001
| 0.37 (0.24, 0.57) |
<0.0001
|
MSP1 3D7 | 11,844.8 | 0.62 (0.41, 0.94) |
0.025
| 0.60 (0.39, 0.92) |
0.019
| 0.61 (0.40, 0.94) |
0.025
|
MSP2 3D7 | 18,300.8 | 0.47 (0.29, 0.78) |
0.0032
| 0.47 (0.28, 0.78) |
0.0034
| 0.47 (0.28, 0.78) |
0.0038
|