Dataset Information

Antibodies to full-length and the DBL5 domain of VAR2CSA in pregnant women after long-term implementation of intermittent preventive treatment in Etoudi, Cameroon.

ABSTRACT: In high malaria transmission settings, the use of sulfadoxine-pyrimethamine-based intermittent preventive treatment during pregnancy (IPTp-SP) has resulted in decreased antibody (Ab) levels to VAR2CSA. However, information of Ab levels in areas of low or intermediate malaria transmission after long-term implementation of IPTp-SP is still lacking. The present study sought to evaluate antibody prevalence and levels in women at delivery in Etoudi, a peri-urban area in the capital of Yaoundé, Cameroon, that is a relatively low-malaria transmission area. Peripheral plasma samples from 130 pregnant women were collected at delivery and tested for IgG to the full-length recombinant VAR2CSA (FV2) and its most immunogenic subdomain, DBL5. The study was conducted between 2013 and 2015, approximately ten years after implementation of IPTp-SP in Cameroon. About 8.6% of the women attending the clinic had placental malaria (PM). One, two or 3 doses of SP did not impact significantly on either the percentage of women with Ab to FV2 and DBL5 or Ab levels in Ab-positive women compared to women not taking SP. The prevalence of Ab to FV2 and DBL5 was only 36.9% and 36.1%, respectively. Surprisingly, among women who had PM at delivery, only 61.5% and 57.7% had Ab to FV2 and DBL5, respectively, with only 52.9% and 47.1% in PM-positive paucigravidae and 77.7% of multigravidae having Ab to both antigens. These results suggest that long-term implementation of IPTp-SP in a low-malaria transmission area results in few women having Ab to VAR2CSA.

SUBMITTER: Djontu JC

PROVIDER: S-EPMC7428160 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Antibodies to full-length and the DBL5 domain of VAR2CSA in pregnant women after long-term implementation of intermittent preventive treatment in Etoudi, Cameroon.

Djontu Jean Claude JC Lloyd Yukie Michelle YM Megnekou Rosette R Seumko'o Reine Medouen Ndeumou RMN Salanti Ali A Taylor Diane Wallace DW Leke Rose Gana Fomban RGF

PloS one 20200814 8

In high malaria transmission settings, the use of sulfadoxine-pyrimethamine-based intermittent preventive treatment during pregnancy (IPTp-SP) has resulted in decreased antibody (Ab) levels to VAR2CSA. However, information of Ab levels in areas of low or intermediate malaria transmission after long-term implementation of IPTp-SP is still lacking. The present study sought to evaluate antibody prevalence and levels in women at delivery in Etoudi, a peri-urban area in the capital of Yaoundé, Camero ...[more]

PMID: 32797068

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Project description:Plasmodium falciparum malaria remains one of the world's leading causes of human suffering and poverty. Each year, the disease takes 1-3 million lives, mainly in sub-Saharan Africa. The adhesion of infected erythrocytes (IEs) to vascular endothelium or placenta is the key event in the pathogenesis of severe P. falciparum infection. In pregnant women, the parasites express a single and unique member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family named VAR2CSA, which is associated with the ability of the IEs to adhere specifically to chondroitin sulphate A (CSA) in the placenta. Several Duffy-binding-like domains from VAR2CSA molecules have been shown in vitro to bind to CSA, but it has also been demonstrated that Duffy-binding-like domains from PfEMP1 proteins other than VAR2CSA can bind CSA. In addition, the specificity of the binding of VAR2CSA domains to glycosaminoglycans does not match that of VAR2CSA-expressing IEs. This has led to speculation that the domains of native VAR2CSA need to come together to form a specific binding site or that VAR2CSA might bind to CSA through a bridging molecule. Here, we describe the expression and purification of the complete extracellular region of VAR2CSA secreted at high yields from insect cells. Using surface plasmon resonance, we demonstrate that VAR2CSA alone binds with nanomolar affinity to human chondroitin sulphate proteoglycan and with significantly weaker affinity to other glycosaminoglycans, showing a specificity similar to that observed for IEs. Antibodies raised against full-length VAR2CSA completely inhibit recombinant VAR2CSA binding, as well as parasite binding to chondroitin sulphate proteoglycan. This is the first study to describe the successful production and functionality of a full-length PfEMP1. The specificity of the binding and anti-adhesion potency of induced IgG, together with high-yield production, encourages the use of full-length PfEMP1 in vaccine development strategies.

Project description:BackgroundIntermittent preventive treatment is recommended for pregnant women living in malaria endemic countries due to benefits for both mother and baby. However, the impact may not be the same in HIV-positive pregnant women, as HIV infection impairs a woman's immunity.ObjectivesTo compare intermittent preventive treatment regimens for malaria in HIV-positive pregnant women living in malaria-endemic areas.Search strategyIn June 2011, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE; EMBASE; LILACS, the metaRegister of Controlled Trials (mRCT), reference lists and conference abstracts. We also contacted researchers and organizations for information on relevant trials.Selection criteriaRandomized controlled trials comparing different intermittent preventive treatment regimens for preventing malaria in HIV-positive pregnant women in malaria-endemic areas.Data collection and analysisTwo authors extracted data and assessed risk bias. Dichotomous variables were combined using risk ratios (RR) and mean differences (MD) for continuous outcomes, both with 95% confidence intervals (CI).Main resultsTwo randomized trials with 722 HIV-positive pregnant women were included, comparing monthly regimens of sulfadoxine-pyrimethamine (SP) to the standard 2-dose regimen in the second and third trimesters. There were no statistically significant differences between monthly SP and 2-dose SP in rates of maternal anaemia, low birth weight, and neonatal mortality. In primigravidae and secondigravidiae, the monthly regimen was associated with less placental parasitaemia (RR 0.38, 95% CI 0.21 to 0.70, two trials) and less peripheral parasitaemia (RR 0.25, 95% CI 0.14 to 0.43, two trials), but no effect was demonstrated in multigravid women. Babies born to primigravidae and secundigravida women on monthly SP had a higher mean birth weight (weighted mean difference (WMD) 130 g; 95% CI 120 g to 150 g, two trials) than babies born to mothers on 2-dose SP. Multigravidae women treated with monthly SP had significant higher haemoglobin level than those treated with treated 2 dose SP (WMD 0.21 g/dL, 95% CI 0.15 g/dL to 0.27 g/dL, one trial). There were no trials that assessed other treatment regimens for intermittent preventive treatment in HIV-positive pregnant women.Authors' conclusionsThree or more doses of SP is superior to the standard two doses in HIV-positive pregnant women. However, since SP cannot be administered concurrently with co-trimoxazole - a drug often recommended for infection prophylaxis in HIV-positive pregnant women, new drugs and research is needed to address needs of HIV-positive pregnant women.

Project description:BackgroundAn estimated 30 million women give birth annually in malaria endemic areas of sub-Saharan Africa. Malaria in pregnancy is associated with an increased risk of adverse maternal and infant outcomes. To combat the adverse effects of MiP, the World Health Organization (WHO) recommends the provision of intermittent preventive treatment in pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) in areas of moderate to high malaria transmission. In 2012, the WHO updated its policy with respect to IPTp administration to recommend administration at each antenatal care visit in the second and third trimesters, with a minimum of three, rather than two, doses. While rapid improvements in coverage were expected, gains have occurred more slowly than anticipated.MethodsThe President's Malaria Initiative (PMI) assessed IPTp uptake before and after countries implemented the new WHO policy, and assessed how long it took for implementation to occur, using a combination of data from household surveys, routine health management information systems, and programmatic data provided to PMI.ResultsIt took an average of 2 years for countries to complete the process of revising their IPTp policies, and it was not until 2015 that all 17 PMI countries had updated their policies. Policy dissemination and training had not been completed in several countries as of early 2018, and only seven countries had fully implemented the new policy including updating their antenatal care registers to collect information on IPTp3+ coverage. The coverage of IPTp1+, 2+, and 3+ has increased by 19, 16, and 13 percentage points since the revised IPTp policy adoption.DiscussionOverall, coverage of both IPTp2+ and IPTp3+ has improved in recent years. The change in policy from a minimum of two to a minimum of three doses has likely contributed to these improvements. Progress has been slow, likely related to the complicated process of policy adoption exacerbated by the lag in measurement through national household surveys. The impact of future policy changes may be more readily seen if the policy change and implementation process were more streamlined and coordinated between key stakeholders (National Malaria Control Programmes and Reproductive Health Programmes), with more real-time data reporting.

Dataset Information

Antibodies to full-length and the DBL5 domain of VAR2CSA in pregnant women after long-term implementation of intermittent preventive treatment in Etoudi, Cameroon.

Publications

Antibodies to full-length and the DBL5 domain of VAR2CSA in pregnant women after long-term implementation of intermittent preventive treatment in Etoudi, Cameroon.

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