The role of RIFINs and their interaction with blood type in vulnerability to severe malaria in Malian children

项目总结/摘要 恶性疟原虫每年在全世界造成近43.5万人死亡。严重疟疾的受害者是 主要是撒哈拉以南地区的儿童，他们可能会出现严重贫血或无法唤醒的昏迷症状。 重症疟疾的发病机制知之甚少，但通过粘附变体的表达介导 受感染红细胞表面抗原（VSA）。这些VSA参与隔离和玫瑰花结， 独特的毒力因子，使寄生虫逃避宿主的免疫反应，并防止清除在 脾脏特别是，ABO血型对玫瑰花结至关重要，玫瑰花结是感染的 和未感染的红细胞。A型血的人特别容易患上严重的疟疾， 不像O型血的人，他们似乎对严重的疾病有相对的保护。一个相对未经研究的 最近发现，VSA家族，即重复散布家族（RIFIN）蛋白，在 玫瑰花结RIFIN优先结合血型A抗原，形成比血型A抗原更大、更紧密的RIFIN。 O. RIFIN可能介导ABO血型和严重疟疾易感性之间的关联;这些基因可能是一种免疫调节因子。 蛋白质似乎也是保护性免疫的目标。针对RIFIN的体液免疫应答 与无症状感染有关。因此，我们认为RIFIN的一个子集在以下方面发挥着关键作用： 严重的疟疾发病机制，缺乏对该亚群免疫力的个体最容易感染 患上严重的疟疾在2014年开始于马里的一项病例对照研究中， 严重疟疾病例的样本和匹配的无并发症疟疾对照。在此，我们建议 使用下一代RNA测序技术鉴定和测序在严重疟疾中表达的RIFIN。 使用定制的蛋白质微阵列，我们将确定是否缺乏这些RIFIN蛋白的抗体， 与严重疾病的发展有关。在目标1中，我们将确定RIFIN转录本的亚组， 在严重疟疾受试者与匹配的无并发症疟疾对照者中的差异表达， RNA测序我们假设RIFIN-As的一个子集将主要在严重疟疾病例中表达， 与其他感染中RIFIN-As异质组的表达相反。在目标2中， 我们将使用在Aim 1和其他寄生虫抗原中鉴定的主要RIFIN转录物来填充定制的 蛋白质微阵列，以确定与严重的易感性增加相关的RIFIN蛋白质的子集， 疟疾我们假设，患有严重疟疾的儿童急性病患者的血清将识别较少的RIFIN蛋白 在蛋白质微阵列上，与他们的恢复期血清和来自匹配的血清相比， 控制无并发症的疟疾，特别是A型血的严重疟疾病例。候选人将 获得生物信息学分析的宝贵专业知识，特别是来自微阵列和转录组数据的 高通量测序平台;使用流行病学技术进行翻译感染 疾病研究;并应用这些技能来支持有效的公共卫生干预措施，如疫苗。

PROJECT SUMMARY/ABSTRACT Plasmodium falciparum causes nearly 435,000 deaths annually worldwide. Victims of severe malaria are predominantly sub-Saharan children, who may present with symptoms of severe anemia or unarousable coma. The pathogenesis of severe malaria is poorly understood but mediated by the expression of adhesive variant surface antigens (VSAs) on infected red blood cells. These VSAs are involved in sequestration and rosetting, unique virulence factors that allow the parasite to evade host immune responses and prevent clearance in the spleen. In particular, ABO blood groups are critical for rosetting, which is the spontaneous binding of infected and uninfected erythrocytes together. Individuals with blood type A are particularly vulnerable to severe malaria, unlike those with blood type O who appear relatively protected against severe disease. A relatively unstudied family of VSAs, the repetitive interspersed family (RIFIN) proteins, have been recently found to be important in rosetting. RIFINs preferentially bind blood type A antigens, forming larger and tighter rosettes than in blood type O. RIFINs may mediate the association between ABO blood type and severe malaria susceptibility; these proteins also appear to be targets for protective immunity. Humoral immune responses against RIFINs have been correlated with asymptomatic infections. As such, we posit that a subset of RIFINs play a critical role in severe malaria pathogenesis and that individuals who lack immunity to this subset are the most susceptible to develop severe malaria. In a case-control study that began in Mali in 2014, our group collected blood and serum samples from severe malaria cases and matched controls with uncomplicated malaria. Here, we propose to identify and sequence RIFINs expressed in severe malaria using next-generation RNA-sequencing technologies. Using a custom protein microarray, we will then determine whether a lack of antibodies to these RIFIN proteins is associated with developing severe disease. In Aim 1, we will identify subgroups of RIFIN transcripts that are differentially expressed in subjects with severe malaria versus matched controls with uncomplicated malaria via RNA-Seq. We hypothesize that a subset of RIFIN-As will be predominantly expressed in severe malaria cases with blood type A, in contrast to expression of a heterogeneous group of RIFIN-As in other infections. In Aim 2, we will use the predominant RIFIN transcripts identified in Aim 1 and other parasite antigens to populate a custom protein microarray in order to define a subset of RIFIN proteins associated with increased vulnerability to severe malaria. We hypothesize that sera from children acutely ill with severe malaria will recognize fewer RIFIN proteins on a protein microarray and react to them less intensely than their convalescent sera and sera from matched controls with uncomplicated malaria, particularly for severe malaria cases with blood type A. The candidate will gain valuable expertise in bioinformatics analysis, particularly from microarrays and transcriptomic data from high-throughput sequencing platforms; use epidemiological techniques to conduct translational infectious disease research; and apply these skills to support effective public health interventions such as a vaccine.