Placental Colonization by Treponema Pallidum, Congenital Syphilis & Novel Vaccine

 描述（由申请人提供）：据估计，全球每年新发梅毒病例超过1000万例，其中约40%的先天性梅毒病例导致胎儿丢失或围产期死亡。此外，大约一半存活的婴儿有严重的后遗症。梅毒的成功控制需要更好地了解梅毒螺旋体的关键毒力因子，梅毒螺旋体，以及重症疾病的抗原标志物的额外知识是必要的。根据我们的初步数据，我们假设：（1）T。苍白球与胎盘的侵袭和定植有关，（2）抗粘附素母源抗体的存在能够阻断粘附，可能导致不太严重或没有先天性感染，（3）这些抗原可以作为候选疫苗。对这一假说的验证将有助于实现我们的长期目标，了解先天性梅毒的发病机制和开发有效的疫苗。我们建议进行第一次全面的分子探索的作用，三个已知的和假定的T。体外和体内先天性梅毒中的苍白球粘附素，并测试针对这些蛋白质的抗体与先天性梅毒结果的关联。使用一种高度新颖的免疫方法，我们还将评估这些抗原作为梅毒兔感染模型中候选疫苗的潜力。 由于T.苍白球在体外，其genetc棘手性，我们将采用几种创新的方法来执行我们提出的研究。例如，使用生物发光的、非感染性的、非粘附性螺旋体伯氏疏螺旋体来表达T。pallidum基因，我们发现T.苍白球TP 0435脂蛋白是一种胎盘细胞粘附素。我们还将研究其他两个假定的胎盘粘附素，TP 0954和层粘连蛋白/纤连蛋白结合脂蛋白TP 0136的作用。TP 0954与恶性疟原虫PfEMP 1的var 2CSA结构域相似，这有助于疟原虫在胎盘中定植，对发育中的胎儿造成极大伤害。本项目的目标是：确定T。使用异源表达系统研究梅毒粘附素与胎盘组织的结合（目的1）;确定孕妇对梅毒的适应性免疫应答对胎盘定植和妊娠结局的影响（目的2）;确定特异性粘附素或粘附素组合是否可用作疫苗诱导对梅毒的保护性免疫（目的3）。意义该应用程序利用了独特的资源：Centurion-Lara博士在螺旋体方面的临床和分子专业知识，以及从秘鲁梅毒孕妇中获得的用于研究先天性梅毒的样本，再加上Giacani博士沿着使用梅毒兔模型的实验知识和熟练程度，以及Parveen博士在螺旋体-宿主相互作用方面的强大专业知识。这将是第一个这样的全面研究，将提高对先天性梅毒的理解，也将导致更好的诊断工具和预防梅毒的疫苗策略的发展。

 DESCRIPTION (provided by applicant): An estimated >10 million new cases of syphilis occur worldwide every year with ~40% of congenital syphilis cases resulting in fetal loss or perinatal death. Moreover, approximately half of the surviving infants suffer serious sequelae. The successful control of syphilis requires a better understanding of critical virulence factors of Treponema pallidum, the syphilis spirochete, and additional knowledge of the antigenic markers of severe disease is warranted. Based upon our preliminary data, we hypothesize that (1) specific adhesins of T. pallidum are associated with invasion and colonization of placenta, (2) the presence of anti- adhesin maternal antibodies capable of blocking adherence might result in less severe or no congenital infections, and (3) these antigens could serve as vaccine candidates. Testing of this hypothesis will help achieve our long-term goals to understand congenital syphilis pathogenesis and develop effective vaccine. We propose to perform the first comprehensive molecular exploration of the role of three known and putative T. pallidum adhesins in congenital syphilis ex-vivo and in vivo, and to test the association of antibodies against these proteins with the congenital syphilis outcomes. Using a highly novel immunization approach, we will also assess the potential of these antigens as vaccine candidates in the rabbit infection model of syphilis. Due to the inability to cultivate T. pallidum in vitro, and its genetc intractability, we will employ several innovative approaches to perform our proposed studies. For instance, using a bioluminescent, non-infectious, non-adherent spirochete Borrelia burgdorferi to express T. pallidum genes, we discovered that T. pallidum TP0435 lipoprotein is a placental cell adhesin. We will also examine the role of two other putative placental adhesins, TP0954 and the laminin/fibronectin-binding lipoprotein TP0136. TP0954 exhibits similarity with the var2CSA domain of PfEMP1 of Plasmodium falciparum, which facilitates placental colonization by the malaria parasite causing great harm to the developing fetus. The goals of this project are to: determine the role of T. pallidum adhesins in binding to placental tissue usin a heterologous expression system (Aim 1); determine the impact of the adaptive immune response against syphilis in pregnant women on both placental colonization and on pregnancy outcomes (Aim 2); and determine whether specific adhesins or a combination of adhesins can be used as vaccine to induce protective immunity against syphilis (Aim 3). Significance. This application takes advantage of unique resources: clinical and molecular expertise of Dr. Centurion-Lara on treponemes and access to samples from syphilitic pregnant women in Peru for studying congenital syphilis, coupled with the experimental know-how and proficiency of using rabbit model of syphilis of Dr. Giacani along with the strong expertise of Dr. Parveen in spirochetes-host interactions. This will be the first such all-inclusive study that will enhance th understanding of congenital syphilis and will also lead to development of better diagnostic tools and vaccine strategy against syphilis.