Genetic and functional studies of var2csa in placental malaria

var2csa 在胎盘疟疾中的遗传和功能研究

• 批准号: 8785243
• 负责人: Steven Richard Meshnick
• 金额: $ 31.84万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8785243
• 关键词: Adverse effects; Affinity; Alleles; Antibodies; Area; Avidity; Baculoviruses; Binding; Biochemistry; Biological; Biological Assay; Biology; Biosensor; Birth; Birth Weight; Blood; Cells; Chondroitin Sulfate A; Clinical Data; Cloning; Code; Codon Nucleotides; Collaborations; DNA; Development; Dideoxy Chain Termination DNA Sequencing; Engineering; Enrollment; Epidemiology; Erythrocytes; Falciparum Malaria; Foundations; Funding; Genes; Genetic; Goals; Gravidity; Health; ID2 gene; In Vitro; Individual; Inflammation; Insecta; Ligand Binding; Link; Longitudinal Studies; Low Birth Weight Infant; Malaria; Malaria Vaccines; Malawi; Measures; Mediating; Membrane; Morbidity - disease rate; Newborn Infant; Outcome; Parasitemia; Parasites; Pathogenesis; Pathogenicity; Patients; Persons; Placenta; Plasmodium falciparum; Polyvalent Vaccine; Population Dynamics; Population Sizes; Pregnancy; Pregnant Women; Prevention; Preventive; Primigravidities; Proteins; RNA; RNA-Directed DNA Polymerase; Reaction; Recombinant Proteins; Recombinants; Research; Research Personnel; Sampling; Second Pregnancy Trimester; Serum; Surface; System; Technology; Universities; Ursidae Family; Vaccines; Variant; Woman; Work; acquired immunity; adaptive immunity; base; cohort; deep sequencing; feeding; immunogenic; immunogenicity; immunoreactivity; innovation; next generation; offspring; peripheral blood; prevent; screening; trial comparing; vaccine candidate; vaccine development

DESCRIPTION (provided by applicant): Falciparum malaria parasites sequester in placentae and imperil millions of pregnant women and newborns each year. Sequestration is mediated by P. falciparum VAR2CSA proteins inserted on the erythrocyte surface which bind to placental chondroitin sulfate A (CSA), produce placental inflammation, and result in low birth weight (LBW) babies. Adaptive immunity to VAR2CSA protects pregnant women and newborns from malaria morbidity. VAR2CSA is large and diverse with incompletely described antigenic and immunogenic domains, but one 2.4 kb region of var2csa, encodes ID1-DBL2X-ID2, which binds CSA with high affinity when expressed in vitro. This recombinant protein elicits potent binding inhibitory antibodies and thus has great promise as a vaccine candidate. However, because VAR2CSA is highly diverse, a polyvalent vaccine might be necessary. Here we propose to interrogate var2csa ID1-DBL2X-ID2 diversity and identify potentially pathogenic variants in Malawian pregnant women, and then measure the CSA binding and immunogenicity of expressed recombinants. 200 pregnant women with both 2nd trimester and delivery parasitemias will be selected from a 1600-person trial comparing Intermittent Screening and Treatment (IST) with Intermittent Preventive Therapy (IPT). They will be divided into 4 groups: primigravidae with and without low-birth weight (LBW) offspring and multigravidae with or without LBW offspring. From each woman, we will obtain 3 parasite samples: peripheral blood from the 2nd trimester and from delivery, and from placental blood. For the first aim, each sample type from each group will be pooled (12 pools) and deep-sequenced across the ID1-DBL2X-ID2 region. We will identify variants associated with primigravidity and LBW. In the second aim, we will use qPCR and reverse-transcriptase qPCR to compare population sizes of the 50 most common variants within each woman over the course of pregnancy. We hypothesize that the most pathogenic variants will be more common in the 2nd trimester than at delivery. In the third aim, we will synthesize and express recombinants of the variants that best fit these criteria and measure both their in vitro CSA-binding and immunogenicity. This proposal represents a new collaboration between the UNC group, with expertise in epidemiology and deep sequencing, and the University of Copenhagen group, a leader in var2csa biology and vaccine development. This proposal will help elucidate the pathogenesis of malaria in pregnancy and directly inform the on-going development of a vaccine against pregnancy-associated malaria.

描述（由申请人提供）：恶性疟原虫寄生在胎盘中，每年危及数百万孕妇和新生儿。隔离是由插入红细胞表面的恶性疟原虫 VAR2CSA 蛋白介导的，该蛋白与胎盘硫酸软骨素 A (CSA) 结合，产生胎盘炎症，并导致低出生体重 (LBW) 婴儿。对 VAR2CSA 的适应性免疫可保护孕妇和新生儿免受疟疾发病。 VAR2CSA 庞大且多样，抗原和免疫原性结构域描述不完全，但 var2csa 的一个 2.4 kb 区域编码 ID1-DBL2X-ID2，在体外表达时以高亲和力结合 CSA。这种重组蛋白可引发有效的结合抑制抗体，因此作为候选疫苗具有广阔的前景。然而，由于 VAR2CSA 高度多样化，因此可能需要多价疫苗。在这里，我们建议询问 var2csa ID1-DBL2X-ID2 多样性并鉴定马拉维孕妇中潜在的致病变异，然后测量表达重组体的 CSA 结合和免疫原性。将从一项 1600 人试验中选出 200 名患有妊娠第二期和分娩寄生虫血症的孕妇，该试验比较间歇性筛查和治疗 (IST) 与间歇性预防性治疗 (IPT)。它们将被分为 4 组：有或没有低出生体重 (LBW) 后代的初产妇和有或没有低出生体重 (LBW) 后代的多孕妇。我们将从每位女性身上获取 3 个寄生虫样本：妊娠第二个月和分娩时的外周血，以及胎盘血。对于第一个目标，每组中的每种样本类型将被合并（12 个池）并在 ID1-DBL2X-ID2 区域进行深度测序。我们将识别与初产和低体重相关的变异。在第二个目标中，我们将使用 qPCR 和逆转录酶 qPCR 来比较每位女性在怀孕期间 50 种最常见变异的群体规模。我们假设最具致病性的变异在妊娠第二期比分娩时更常见。第三个目标是，我们将合成并表达最符合这些标准的变体重组体，并测量它们的体外 CSA 结合性和免疫原性。该提案代表了拥有流行病学和深度测序专业知识的北卡罗来纳大学团队与 var2csa 生物学和疫苗开发领域领导者哥本哈根大学团队之间的新合作。该提案将有助于阐明妊娠期疟疾的发病机制，并直接为正在进行的妊娠相关疟疾疫苗的开发提供信息。