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1.
Pathogens ; 12(6)2023 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-37375534

RESUMEN

Intermittent preventive treatment in pregnancy with sulfadoxine and pyrimethamine (IPTp-SP) is a key component in the malaria control strategy implemented in Africa. The aim of this study was to determine IPTp-SP adherence and coverage, and the impact on maternal infection and birth outcomes in the context of widespread SP resistance in the city of Douala, Cameroon. Clinical and demographic information were documented among 888 pregnant women attending 3 health facilities, from the antenatal care visit to delivery. Positive samples were genotyped for P. falciparum gene (dhfr, dhps, and k13) mutations. The overall IPTp-SP coverage (≥three doses) was 17.5%, and 5.1% received no dose. P. falciparum prevalence was 16%, with a predominance of submicroscopic infections (89.3%). Malaria infection was significantly associated with locality and history of malaria, and it was reduced among women using indoor residual spraying. Optimal doses of IPTp-SP were significantly associated with reduced infection among newborns and women (secundiparous and multiparous), but there was no impact of IPTp-SP on the newborn bodyweight. Pfdhfr-Pfdhps quintuple mutants were over-represented (IRNI-FGKAA, IRNI-AGKAA), and sextuple mutants (IRNI-AGKAS, IRNI-FGEAA, IRNI-AGKGS) were also reported. The Pfk13 gene mutations associated with artemisinin resistance were not detected. This study highlights the role of ANC in achieving optimal SP coverage in pregnant women, the mitigated impact of IPTp-SP on malaria outcomes, and the high prevalence of multiple SP-resistant P. falciparum parasites in the city of Douala that could compromise the efficacy of IPTp-SP.

2.
Nat Commun ; 12(1): 5838, 2021 10 05.
Artículo en Inglés | MEDLINE | ID: mdl-34611164

RESUMEN

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family members mediate receptor- and tissue-specific sequestration of infected erythrocytes (IEs) in malaria. Antibody responses are a central component of naturally acquired malaria immunity. PfEMP1-specific IgG likely protects by inhibiting IE sequestration and through IgG-Fc Receptor (FcγR) mediated phagocytosis and killing of antibody-opsonized IEs. The affinity of afucosylated IgG to FcγRIIIa is up to 40-fold higher than fucosylated IgG, resulting in enhanced antibody-dependent cellular cytotoxicity. Most IgG in plasma is fully fucosylated, but afucosylated IgG is elicited in response to enveloped viruses and to paternal alloantigens during pregnancy. Here we show that naturally acquired PfEMP1-specific IgG is strongly afucosylated in a stable and exposure-dependent manner, and efficiently induces FcγRIIIa-dependent natural killer (NK) cell degranulation. In contrast, immunization with a subunit PfEMP1 (VAR2CSA) vaccine results in fully fucosylated specific IgG. These results have implications for understanding protective natural- and vaccine-induced immunity to malaria.


Asunto(s)
Antígenos de Protozoos/metabolismo , Plasmodium falciparum/metabolismo , Plasmodium falciparum/patogenicidad , Anticuerpos Antiprotozoarios/metabolismo , Antígenos de Protozoos/inmunología , Femenino , Humanos , Inmunoglobulina G/metabolismo , Malaria Falciparum/inmunología , Malaria Falciparum/prevención & control , Embarazo , Vacunación
3.
Front Immunol ; 12: 610305, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33968015

RESUMEN

Sequestration of Plasmodium falciparum-infected erythrocytes expressing the VAR2CSA antigen in the placenta results in poor pregnancy outcomes, including low birth weight and maternal anemia. Antigen-specific antibody-mediated immunity is acquired during successive pregnancies. Thus, evaluating VAR2CSA-specific IgG profiles among pregnant women will increase knowledge on the immunological mechanisms associated with protection, and help in the development of VAR2CSA-based placental malaria vaccines. Using the PAMVAC candidate vaccine antigen, we assessed anti-VAR2CSA IgG subclass responses of a cohort of pregnant Beninese, and analyzed their relationships with pregnancy outcomes. Cytophilic IgG1 and IgG3 responses were the most frequent, with prevalences ranging from 28% (IgG3) up to 50% (IgG1). Elevated levels of VAR2CSA-specific total IgG and cytophilic IgG3 during pregnancy were consistently associated with higher birth weights, whilst high levels of IgG4 were associated with a reduced risk of placental infections. This suggests that protective anti-VAR2CSA IgG responses are coordinated between both cytophilic and non-cytophilic antibodies.


Asunto(s)
Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/inmunología , Inmunoglobulina G/inmunología , Malaria Falciparum/inmunología , Malaria Falciparum/parasitología , Plasmodium falciparum/inmunología , Adulto , Anticuerpos Antiprotozoarios/sangre , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunoglobulina G/sangre , Recién Nacido de Bajo Peso , Malaria Falciparum/transmisión , Embarazo , Complicaciones Parasitarias del Embarazo/inmunología , Complicaciones Parasitarias del Embarazo/parasitología , Resultado del Embarazo , Factores de Riesgo , Adulto Joven
4.
Front Immunol ; 12: 634508, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33717176

RESUMEN

In areas where Plasmodium falciparum transmission is endemic, clinical immunity against malaria is progressively acquired during childhood and adults are usually protected against the severe clinical consequences of the disease. Nevertheless, pregnant women, notably during their first pregnancies, are susceptible to placental malaria and the associated serious clinical outcomes. Placental malaria is characterized by the massive accumulation of P. falciparum infected erythrocytes and monocytes in the placental intervillous spaces leading to maternal anaemia, hypertension, stillbirth and low birth weight due to premature delivery, and foetal growth retardation. Remarkably, the prevalence of placental malaria sharply decreases with successive pregnancies. This protection is associated with the development of antibodies directed towards the surface of P. falciparum-infected erythrocytes from placental origin. Placental sequestration is mediated by the interaction between VAR2CSA, a member of the P. falciparum erythrocyte membrane protein 1 family expressed on the infected erythrocytes surface, and the placental receptor chondroitin sulfate A. VAR2CSA stands today as the leading candidate for a placental malaria vaccine. We recently reported the safety and immunogenicity of two VAR2CSA-derived placental malaria vaccines (PRIMVAC and PAMVAC), spanning the chondroitin sulfate A-binding region of VAR2CSA, in both malaria-naïve and P. falciparum-exposed non-pregnant women in two distinct Phase I clinical trials (ClinicalTrials.gov, NCT02658253 and NCT02647489). This review discusses recent advances in placental malaria vaccine development, with a focus on the recent clinical data, and discusses the next clinical steps to undertake in order to better comprehend vaccine-induced immunity and accelerate vaccine development.


Asunto(s)
Antígenos de Protozoos/uso terapéutico , Desarrollo de Medicamentos , Vacunas contra la Malaria/uso terapéutico , Malaria Falciparum/prevención & control , Placenta/parasitología , Complicaciones Parasitarias del Embarazo/prevención & control , Animales , Antígenos de Protozoos/efectos adversos , Antígenos de Protozoos/inmunología , Femenino , Interacciones Huésped-Parásitos , Humanos , Inmunización , Inmunogenicidad Vacunal , Vacunas contra la Malaria/efectos adversos , Vacunas contra la Malaria/inmunología , Malaria Falciparum/inmunología , Malaria Falciparum/parasitología , Placenta/inmunología , Embarazo , Complicaciones Parasitarias del Embarazo/inmunología , Complicaciones Parasitarias del Embarazo/parasitología , Resultado del Tratamiento
5.
Expert Rev Vaccines ; 20(2): 215-226, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33472449

RESUMEN

Introduction: Several malaria vaccines are under various phases of development with some promising results. In placental malaria (PM) a deliberately anti-disease approach is considered as many studies have underlined the key role of VAR2CSA protein, which therefore represents the leading vaccine candidate. However, evidence indicates that VAR2CSA antigenic polymorphism remains an obstacle to overcome.Areas covered: This review analyzes the progress made thus far in developing a VAR2CSA-based vaccine, and addresses the current issues and challenges that must be overcome to develop an effective PM vaccine.Expert opinion: Phase I trials of PAMVAC and PRIMVAC VAR2CSA vaccines have shown more or less satisfactory results with regards to safety and immunogenicity. The second generation of VAR2CSA-based vaccines could benefit from optimization approaches to broaden the activity spectrum against various placenta-binding isolates through continued advances in the structural understanding of the interaction with CSA.


Asunto(s)
Antígenos de Protozoos/inmunología , Vacunas contra la Malaria/administración & dosificación , Malaria Falciparum/prevención & control , Animales , Femenino , Humanos , Inmunogenicidad Vacunal , Vacunas contra la Malaria/efectos adversos , Vacunas contra la Malaria/inmunología , Malaria Falciparum/inmunología , Placenta/inmunología , Placenta/parasitología , Plasmodium falciparum/inmunología , Embarazo , Complicaciones Parasitarias del Embarazo/inmunología , Complicaciones Parasitarias del Embarazo/prevención & control
6.
Clin Infect Dis ; 73(2): e355-e361, 2021 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-32569359

RESUMEN

BACKGROUND: Malaria infections in the first trimester of pregnancy are frequent and deleterious for both mother and child health. To investigate if these early infections are newly acquired or already present in the host, we assessed whether parasites detected before pregnancy and those detected in early pregnancy are the same infection. METHODS: We used data from the preconceptional "RECIPAL" study (Benin, 2014-2017). Sixty-three pregnant women of 411 included who had a malaria infection detected by quantitative polymerase chain reaction both before pregnancy and at the first antenatal care (ANC) visit were selected for this study. Two highly polymorphic markers, msp-2 and glurp, and a fragment-analysis method were used to enumerate the Plasmodium falciparum genotypes and to quantify their proportions within isolates. An infection was considered as persistent when identical msp-2 and glurp genotypes were found in the corresponding prepregnancy and early-pregnancy samples. RESULTS: The median time between the 2 malaria screenings was 3 months. The median gestational age at the first ANC visit was 6.4 weeks. Most infections before pregnancy were submicroscopic infections. Based on both msp-2 and glurp genotyping, the infection was similar before and in early pregnancy in 46% (29/63) of cases. CONCLUSIONS: Almost half of P. falciparum infections detected in the first trimester originate before pregnancy. Protecting young women from malaria infection before pregnancy might reduce the prevalence of malaria in early pregnancy and its related poor maternal and birth outcomes.


Asunto(s)
Malaria Falciparum , Malaria , Benin/epidemiología , Niño , Femenino , Genotipo , Humanos , Malaria Falciparum/epidemiología , Plasmodium falciparum/genética , Embarazo
8.
Artículo en Inglés | MEDLINE | ID: mdl-32179528

RESUMEN

The continuous spread of antimalarial drug resistance is a threat to current chemotherapy efficacy. Therefore, characterizing the genetic diversity of drug resistance markers is needed to follow treatment effectiveness and further update control strategies. Here, we genotyped Plasmodium falciparum resistance gene markers associated with sulfadoxine-pyrimethamine (SP) and artemisinin-based combination therapy (ACT) in isolates from pregnant women in Ghana. The prevalence of the septuple IRN I- A/FG K GS/Tpfdhfr/pfdhps haplotypes, including the pfdhps A581G and A613S/T mutations, was high at delivery among post-SP treatment isolates (18.2%) compared to those of first antenatal care (before initiation of intermittent preventive treatment of malaria in pregnancy with sulfadoxine-pyrimethamine [IPTp-SP]; 6.1%; P = 0.03). Regarding the pfk13 marker gene, two nonsynonymous mutations (N458D and A481C) were detected at positions previously related to artemisinin resistance in isolates from Southeast Asia. These mutations were predicted in silico to alter the stability of the pfk13 propeller-encoding domain. Overall, these findings highlight the need for intensified monitoring and surveillance of additional mutations associated with increased SP resistance as well as emergence of resistance against artemisinin derivatives.


Asunto(s)
Antimaláricos , Malaria Falciparum , Parásitos , Preparaciones Farmacéuticas , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Combinación de Medicamentos , Resistencia a Medicamentos/genética , Femenino , Ghana , Humanos , Malaria Falciparum/tratamiento farmacológico , Plasmodium falciparum/genética , Embarazo , Mujeres Embarazadas , Proteínas Protozoarias/uso terapéutico , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Tetrahidrofolato Deshidrogenasa/genética
10.
Clin Infect Dis ; 67(12): 1890-1896, 2018 11 28.
Artículo en Inglés | MEDLINE | ID: mdl-29733338

RESUMEN

Background: Pregnant women are more susceptible to Plasmodium falciparum than before pregnancy, and infection has consequences for both mother and offspring. The World Health Organization recommends that pregnant woman in areas of transmission receive intermittent preventive treatment (IPTp) starting in the second trimester. Consequently, women are not protected during the first trimester, although P. falciparum infections are both frequent and harmful. Methods: A cohort of nulligravid women was followed up during subsequent pregnancy. Malaria was diagnosed by means of microscopy and polymerase chain reaction. Parasites were genotyped at polymorphic loci. Results: Among 275 nulligravidae enrolled, 68 women became pregnant and were followed up during pregnancy. Before pregnancy, P. falciparum prevalence rates were 15% by microscopy and 66% by polymerase chain reaction. Microscopic infection rates increased to 29% until IPTp administration, and their density increased by 20-fold. Conversely, submicroscopic infection rates decreased. After IPTp administration, all types of infections decreased, but they increased again late in pregnancy. The risk of infection during pregnancy was higher in women with a microscopic (odds ratio, 6.5; P = .047) or submicroscopic (3.06; P = .05) infection before pregnancy and was not related to the season of occurrence. Most infections during pregnancy were persistent infections acquired before pregnancy. Conclusions: Microscopic and submicroscopic malaria infections were frequent in nulligravid women from south Benin. During the first trimester of pregnancy, microscopic infections were more frequent, with a higher parasite density, and mainly derived from parasites infecting the woman before conception. Preventive strategies targeting nonpregnant women with a desire for conception need to be designed.


Asunto(s)
Antimaláricos/administración & dosificación , Malaria Falciparum/diagnóstico , Malaria Falciparum/epidemiología , Complicaciones Parasitarias del Embarazo/epidemiología , Adulto , Benin/epidemiología , Estudios de Cohortes , Femenino , Número de Embarazos , Humanos , Plasmodium falciparum/aislamiento & purificación , Embarazo , Prevalencia , Análisis de Regresión , Factores de Riesgo , Adulto Joven
11.
PLoS Negl Trop Dis ; 12(2): e0006279, 2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29432484

RESUMEN

BACKGROUND: Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-falciparum malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy. METHODS AND FINDINGS: Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for Plasmodium spp. Risk factors associated with Plasmodium spp. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes. P. falciparum was the most prevalent Plasmodium species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no P. vivax infections were detected in this cohort, P. malariae (9.2%) and P. ovale (5.8%) infections were observed in samples collected during the first ANV. These non-falciparum infections were also detected in maternal peripheral blood (1.3% for P. malariae and 1.2% for P. ovale) at delivery. Importantly, higher prevalence of P. malariae (5.5%) was observed in placental than peripheral blood while that of P. ovale was similar (1.8% in placental blood). Among the non-falciparum infected pregnant women with paired peripheral and placental samples, P. malariae infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of P. malariae for the placenta. However, no assoctiation of non-falciparum infections and the pregnancy outcomes was observed. CONCLUSIONS: Overall this study provided insights into the molecular epidemiology of Plasmodium spp. infection during pregnancy, indicating placental infection by non-falciparum Plasmodium and the lack of association of these infections with adverse pregnancy outcomes.


Asunto(s)
Malaria/epidemiología , Enfermedades Placentarias/epidemiología , Placenta/parasitología , Plasmodium/aislamiento & purificación , Complicaciones Infecciosas del Embarazo/epidemiología , Benin/epidemiología , Sangre/parasitología , Femenino , Humanos , Epidemiología Molecular , Plasmodium/clasificación , Plasmodium/genética , Embarazo , Resultado del Embarazo , Reacción en Cadena en Tiempo Real de la Polimerasa , Factores de Riesgo
12.
BMJ Open ; 8(1): e019014, 2018 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-29317419

RESUMEN

PURPOSE: REtard de Croissance Intra-uterin et PALudisme (RECIPAL) is an original preconceptional cohort designed to assess the consequences of malaria during the first trimester of pregnancy, which is a poorly investigated period in Africa and during which malaria may be detrimental to the fetus. PARTICIPANTS: For this purpose, a total of 1214 women of reproductive age living in Sô-Ava and Akassato districts (south Benin) were followed up monthly from June 2014 to December 2016 until 411 of them became pregnant. A large range of health determinants was collected both before and during pregnancy from the first weeks of gestation to delivery. Five Doppler ultrasound scans were performed for early dating of the pregnancy and longitudinal fetal growth assessment. FINDINGS TO DATE: Pregnant women were identified at a mean of 6.9 weeks of gestation (wg). Preliminary results confirmed the high prevalence of malaria in the first trimester of pregnancy, with more than 25.4% of women presenting at least one microscopic malarial infection during this period. Most infections occurred before six wg. The prevalence of low birth weight, small birth weight for gestational age (according to INTERGROWTH-21st charts) and preterm birth was 9.3%, 18.3% and 12.6%, respectively. FUTURE PLANS: REtard de Croissance Intra-uterin et PALudisme (RECIPAL) represents at this time a unique resource that will provide information on multiple infectious (including malaria), biological, nutritional and environmental determinants in relation to health outcomes in women of reproductive age, pregnant women and their newborns. It will contribute to better define future recommendations for the prevention of malaria in early pregnancy and maternal malnutrition in Africa. It confirms that it is possible to constitute a preconceptional pregnancy cohort in Africa and provides valuable information for researchers starting cohorts in the future.


Asunto(s)
Desarrollo Fetal , Malaria/complicaciones , Malaria/epidemiología , Complicaciones Infecciosas del Embarazo , Resultado del Embarazo/epidemiología , Nacimiento Prematuro/epidemiología , Adulto , Benin/epidemiología , Estudios de Cohortes , Femenino , Feto/diagnóstico por imagen , Edad Gestacional , Humanos , Recién Nacido , Estimación de Kaplan-Meier , Modelos Logísticos , Masculino , Embarazo , Primer Trimestre del Embarazo , Ultrasonografía Doppler , Ultrasonografía Prenatal , Adulto Joven
13.
Infect Immun ; 86(4)2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29378797

RESUMEN

Malaria in pregnancy can cause serious adverse outcomes for the mother and the fetus. However, little is known about the effects of submicroscopic infections (SMIs) in pregnancy, particularly in areas where Plasmodium falciparum and Plasmodium vivax cocirculate. A cohort of 187 pregnant women living in Puerto Libertador in northwest Colombia was followed longitudinally from recruitment to delivery. Malaria was diagnosed by microscopy, reverse transcription-quantitative PCR (RT-qPCR), and placental histopathology. Gestational age, hemoglobin concentration, VAR2CSA-specific IgG levels, and adhesion-blocking antibodies were measured during pregnancy. Statistical analyses were performed to evaluate the impact of SMIs on birth weight and other delivery outcomes. Twenty-five percent of women (45/180) were positive for SMIs during pregnancy. Forty-seven percent of infections (21/45) were caused by P. falciparum, 33% were caused by P. vivax, and 20% were caused by mixed Plasmodium spp. Mixed infections of P. falciparum and P. vivax were associated with lower gestational age at delivery (P = 0.0033), while other outcomes were normal. Over 60% of women had antibodies to VAR2CSA, and there was no difference in antibody levels between those with and without SMIs. The anti-adhesion function of these antibodies was associated with protection from SMI-related anemia at delivery (P = 0.0086). SMIs occur frequently during pregnancy, and while mixed infections of both P. falciparum and P. vivax were not associated with a decrease in birth weight, they were associated with significant risk of preterm birth. We propose that the lack of adverse delivery outcomes is due to functional VAR2CSA antibodies that can protect pregnant women from SMI-related anemia.

14.
J Infect Dis ; 215(12): 1918-1925, 2017 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-28863469

RESUMEN

Background: Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates the binding and accumulation of infected erythrocytes (IE) to blood vessels and tissues. Specific interactions have been described between PfEMP1 and human endothelial proteins CD36, intercellular adhesion molecule-1 (ICAM-1), and endothelial protein C receptor (EPCR); however, cytoadhesion patterns typical for pediatric malaria syndromes and the associated PfEMP1 members are still undefined. Methods: In a cohort of 94 hospitalized children with malaria, we characterized the binding properties of IE collected on admission, and var gene transcription using quantitative polymerase chain reaction. Results: IE from patients with cerebral malaria were more likely to bind EPCR and ICAM-1 than IE from children with uncomplicated malaria (P = .007). The level of transcripts encoding CIDRα1.4 and CIDRα1.5 domain subclasses was higher in patients with severe disease (P < .05). IE populations exhibiting binding to all 3 receptors had higher levels of transcripts encoding PfEMP1 with CIDRα1.4 and Duffy binding-like (DBL)-ß3 domains than parasites, which only bound CD36. Conclusions: These results underpin the significance of EPCR binding in pediatric malaria patients that require hospital admission, and support the notion that complementary receptor interactions of EPCR binding PfEMP1with ICAM-1 amplifies development of severe malaria symptoms.


Asunto(s)
Antígenos CD/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Malaria Cerebral/parasitología , Malaria Falciparum/parasitología , Plasmodium falciparum/metabolismo , Proteínas Protozoarias/metabolismo , Receptores de Superficie Celular/metabolismo , Adhesión Celular , Preescolar , Células Endoteliales/metabolismo , Receptor de Proteína C Endotelial , Humanos , Lactante , Unión Proteica , Transcripción Genética
15.
Sci Rep ; 7(1): 7768, 2017 08 11.
Artículo en Inglés | MEDLINE | ID: mdl-28801627

RESUMEN

Pregnancy associated malaria (PAM) causes adverse pregnancy and birth outcomes owing to Plasmodium falciparum accumulation in the placenta. Placental accumulation is mediated by P. falciparum protein VAR2CSA, a leading PAM-specific vaccine target. The extent of its antigen diversity and impact on clinical outcomes remain poorly understood. Through amplicon deep-sequencing placental malaria samples from women in Malawi and Benin, we assessed sequence diversity of VAR2CSA's ID1-DBL2x region, containing putative vaccine targets and estimated associations of specific clades with adverse birth outcomes. Overall, var2csa diversity was high and haplotypes subdivided into five clades, the largest two defined by homology to parasites strains, 3D7 or FCR3. Across both cohorts, compared to women infected with only FCR3-like variants, women infected with only 3D7-like variants delivered infants with lower birthweight (difference: -267.99 g; 95% Confidence Interval [CI]: -466.43 g,-69.55 g) and higher odds of low birthweight (<2500 g) (Odds Ratio [OR] 5.41; 95% CI:0.99,29.52) and small-for-gestational-age (OR: 3.65; 95% CI: 1.01,13.38). In two distinct malaria-endemic African settings, parasites harboring 3D7-like variants of VAR2CSA were associated with worse birth outcomes, supporting differential effects of infection with specific parasite strains. The immense diversity coupled with differential clinical effects of this diversity suggest that an effective VAR2CSA-based vaccine may require multivalent activity.


Asunto(s)
Antígenos de Protozoos/genética , Recién Nacido de Bajo Peso , Malaria Falciparum/complicaciones , Malaria Falciparum/parasitología , Enfermedades Placentarias/parasitología , Plasmodium falciparum/genética , Complicaciones Infecciosas del Embarazo/parasitología , Adolescente , Adulto , Benin/epidemiología , Femenino , Variación Genética , Genotipo , Haplotipos , Humanos , Malaui/epidemiología , Plasmodium falciparum/clasificación , Embarazo , Medición de Riesgo , Análisis de Secuencia de ADN , Adulto Joven
16.
Sci Rep ; 7(1): 1414, 2017 05 03.
Artículo en Inglés | MEDLINE | ID: mdl-28469130

RESUMEN

Pregnancy-associated malaria (PAM) is associated with poor pregnancy outcomes. Hemoglobin S (HbS) and hemoglobin C (HbC) mutations are frequently encountered in malaria-endemic areas of Africa, where they protect children from severe and uncomplicated Plasmodium falciparum malaria. However, scant epidemiological data exist on the impact of these Hb variants on PAM. A prospective cohort of 635 Beninese pregnant women was recruited before 24 weeks of gestational age and followed until the end of pregnancy. HbAA, HbAC, and HbAS genotypes were determined and tested for association with pregnancy outcomes and PAM indicators using linear and logistic multivariate models. Newborns from HbAC mothers had higher birthweights than those from HbAA mothers among women infected at any time during pregnancy (mean difference 182.9 g, p = 0.08), or during the first half of pregnancy (654.3 g, p = 0.0006). No such birthweight differences were observed between newborns from HbAS and HbAA mothers. HbAC and HbAS were not associated with other pregnancy outcomes or PAM indicators. In conclusion, HbAC but not HbAS is associated with an improved birth outcome in pregnant women with documented PAM. Higher-birthweight newborns from HbAC mothers may have a survival advantage that contributes to the natural selection of HbC in malaria-endemic areas.


Asunto(s)
Peso al Nacer , Hemoglobina Falciforme/genética , Hemoglobinas Anormales/genética , Malaria/epidemiología , Malaria/genética , Complicaciones Parasitarias del Embarazo/epidemiología , Complicaciones Parasitarias del Embarazo/genética , África Occidental , Femenino , Genotipo , Edad Gestacional , Hemoglobina A/genética , Heterocigoto , Humanos , Embarazo , Estudios Prospectivos
18.
Malar J ; 14: 493, 2015 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-26646943

RESUMEN

BACKGROUND: Malaria is still one of the most prevalent infectious diseases in the world. Sequestration of infected erythrocytes (IEs) is the prime mediator of disease. Cytoadhesion of IEs is mediated by members of the highly diverse Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). A restricted sub-set of var genes encoding for PfEMP1s possessing the domain cassettes DC8 and DC13 were found to bind to the endothelial protein C receptor (EPCR). These var genes were shown to be highly expressed by parasites from patients with severe malaria clinical outcomes compared to those from patients with uncomplicated symptoms. METHODS: In order to further study the molecular mechanisms underlying DC8/DC13 expressing IEs adhesion to EPCR, a method was developed to produce highly pure recombinant EPCR. The IT4 parasite strain was selected on either anti-IT4-VAR19 purified IgG, EPCR or human brain endothelial cell line and their var gene expression profiles as well as their binding phenotypes were compared. The N-terminal region of IT4-VAR19 comprising a full-length DC8 cassette as well as the single EPCR binding CIDRα1.1 domain were also produced, and their immune recognition (IgG) was assessed using plasma samples from Beninese children presenting acute mild malaria, severe malaria or cerebral malaria at the time of their admission to the clinic, and from convalescent-phase plasma collected 30 days after anti-malarial treatment. RESULTS: The multi-domain VAR19-NTS-DBLγ6 binds to EPCR with a greater affinity than the CIDRα1.1 domain alone and this study also demonstrates that VAR19-NTS-DBLγ6 binding to the EPCR-expressing endothelial cell line (HBEC5i) is more pronounced than that of the CIDRα1.1 domain alone. IT4-VAR19 represents the preferentially expressed-PfEMP1 when FCR3-IEs are selected based on their capability to bind EPCR. Notably, no significant difference in the levels of antibodies towards IT4-VAR19 antigens was observed within all clinical groups between plasma samples collected during the acute malaria phase compared to samples collected 30 days after anti-malaria treatment. CONCLUSIONS: These data indicate that even being the preferentially selected IT4-EPCR-binding variant, the IT4-VAR19-DC8 region does not appear to be associated with the acquisition of antibodies during a single severe paediatric malaria episode in Benin.


Asunto(s)
Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos/inmunología , Malaria Cerebral/inmunología , Plasmodium falciparum/inmunología , Proteínas Protozoarias/inmunología , Animales , Antígenos CD/metabolismo , Antígenos de Protozoos/genética , Benin , Adhesión Celular , Preescolar , Estudios de Cohortes , Células Endoteliales/fisiología , Receptor de Proteína C Endotelial , Eritrocitos/parasitología , Eritrocitos/fisiología , Femenino , Genotipo , Humanos , Lactante , Recién Nacido , Masculino , Unión Proteica , Proteínas Protozoarias/genética , Conejos , Receptores de Superficie Celular/metabolismo
19.
PLoS One ; 10(9): e0137695, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26393516

RESUMEN

The VAR2CSA protein of Plasmodium falciparum is transported to and expressed on the infected erythrocyte surface where it plays a key role in placental malaria (PM). It is the current leading candidate for a vaccine to prevent PM. However, the antigenic polymorphism integral to VAR2CSA poses a challenge for vaccine development. Based on detailed analysis of polymorphisms in the sequence of its ligand-binding N-terminal region, currently the main focus for vaccine development, we assessed var2csa from parasite isolates infecting pregnant women. The results reveal for the first time the presence of a major dimorphic region in the functionally critical N-terminal ID1 domain. Parasite isolates expressing VAR2CSA with particular motifs present within this domain are associated with gravidity- and parasite density-related effects. These observations are of particular interest in guiding efforts with respect to optimization of the VAR2CSA-based vaccines currently under development.


Asunto(s)
Antígenos de Protozoos/química , Plasmodium falciparum/metabolismo , Antígenos de Protozoos/inmunología , Antígenos de Protozoos/metabolismo , Eritrocitos/parasitología , Femenino , Estudios de Asociación Genética , Variación Genética , Edad Gestacional , Humanos , Datos de Secuencia Molecular , Filogenia , Plasmodium falciparum/genética , Plasmodium falciparum/aislamiento & purificación , Embarazo , Estructura Terciaria de Proteína , Vacunas Sintéticas/inmunología
20.
Expert Opin Biol Ther ; 15(8): 1173-82, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26051589

RESUMEN

INTRODUCTION: Placental malaria (PM) is a major public health problem that constitutes a significant health concern for the mother, and especially for the developing fetus and offspring. Current means of prevention have limitations, including a restricted window of intervention that excludes the first trimester of pregnancy, and the fact that very few drugs can be used for this purpose. The identification of the VAR2CSA antigen, specific to PM parasites, offers an excellent opportunity to develop a vaccine against this disease. Proof of concept of a first-generation vaccine is nearing completion, and two clinical trials are underway. AREAS COVERED: This review focuses on PM, which is mainly caused by Plasmodium falciparum. The review highlights recent advances and the key milestones that led to the identification of the optimal vaccine target within the large VAR2CSA protein. The paper also points out how future improvements can strengthen this process to achieve an effective vaccine in the field. EXPERT OPINION: The approach taken to develop a P. falciparum erythrocyte membrane protein 1-based vaccine to protect pregnant women is very promising in view of the current difficulties of achieving a sterilizing vaccine against malaria parasite. This approach could help us to control the deleterious effect of malaria infections that characterize severe clinical forms.


Asunto(s)
Descubrimiento de Drogas/tendencias , Vacunas contra la Malaria/administración & dosificación , Malaria Falciparum/prevención & control , Plasmodium falciparum/efectos de los fármacos , Complicaciones Infecciosas del Embarazo/prevención & control , Antígenos de Protozoos/inmunología , Antígenos de Protozoos/metabolismo , Femenino , Humanos , Malaria Falciparum/inmunología , Placenta/efectos de los fármacos , Placenta/inmunología , Embarazo , Complicaciones Infecciosas del Embarazo/inmunología
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