Antibody to P. falciparum in Pregnancy Varies with Intermittent Preventive Treatment Regime and Bed Net Use

Elizabeth H Aitken,Stephen J Rogerson,Mari Luntamo,Bernard Mbewe,Per Ashorn,Teija Kulmala,James G Beeson,Georges Snounou

doi:10.1371/journal.pone.0029874

Elizabeth H Aitken, Stephen J Rogerson + Show 6 more

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https://doi.org/10.1371/journal.pone.0029874

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Abstract

BackgroundAntibodies towards placental-binding P. falciparum are thought to protect against pregnancy malaria; however, environmental factors may affect antibody development. Methods and Findings: Using plasma from pregnant Malawian women, we measured IgG against placental-binding P. falciparum parasites by flow cytometry, and related results to intermittent preventive treatment (IPTp) regime, and bed net use. Bed net use was associated with decreased antibody levels at mid-pregnancy but not at 1 month post partum (1 mpp). At 1 mpp a more intensive IPTp regime was associated with decreased antibody levels in primigravidae, but not multigravidae.Conclusions/SignificanceResults suggest bed nets and IPTp regime influence acquisition of pregnancy-specific P. falciparum immunity.

Highlights

Plasmodium falciparum parasites that accumulate in the placenta express unique variant surface antigens (VSA) including the protein VAR2CSA, which enables the parasitised erythrocyte to adhere to placental chondroitin sulphate-A (CSA) [1]
CSA-VSA IgG was measured in 538 women at enrolment (14– 26 gw) and 364 women at 1 mpp; 355 women had samples assayed at both time points
When the data were stratified by gravidity, there was a significant negative association between bed net use and CSA-VSA IgG at enrolment in primigravidae, but not in multigravidae or secundigravidae

Summary

Introduction

Plasmodium falciparum parasites that accumulate in the placenta express unique variant surface antigens (VSA) including the protein VAR2CSA, which enables the parasitised erythrocyte to adhere to placental chondroitin sulphate-A (CSA) [1]. IgG antibodies towards CSA-VSA (CSA-binding phenotype VSAs) are gravidity dependent and have been associated with protection from malaria-related low birth weight and maternal anaemia [1]. The development of these antibodies may depend on a combination of factors, including maternal genetics, HIV status and parasite exposure, which in turn could vary with the use of intermittent preventive treatment in pregnancy (IPTp) and bed nets. To examine the effect of bed nets and IPTp on CSA-VSA IgG levels we measured antibody towards a CSA-binding parasite line during pregnancy and post partum in pregnant Malawian women participating in a randomised clinical trial of different IPTp regimes. At 1 mpp a more intensive IPTp regime was associated with decreased antibody levels in primigravidae, but not multigravidae

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