New Approaches to Schistosome vaccine antigen discovery

描述（由申请人提供）：血吸虫感染全球超过2亿人。目前只有一种有效的药物在生产中。目前还没有疫苗。针对血吸虫病疫苗开发的研究是对抗耐药寄生虫传播的最佳长期防御措施，并将使大规模药物治疗计划更有效且更具成本效益。疫苗是可行的，因为部分天然免疫力在人类中发展，并且在使用辐射减毒幼虫的实验动物中可以实现70-90%的保护。尽管已经做出了重大努力来确定一些候选疫苗，但世界卫生组织试验的最有希望的抗原在独立试验中未能提供规定的最低40%的保护。这种不良的功效可能是由于许多原因而发生的，但突出了对新方法的需要，以鉴定和测试多体疫苗候选抗原。 我们的长期目标是为人类开发一种有效的疫苗。该提案旨在鉴定在感染早期迁移阶段表达的分子。我们的中心假设是，幼虫分泌和/或表面蛋白是必不可少的成功寄生虫入侵和生存，是免疫消除的主要目标。这源于我们自己和其他人的观察，即皮肤和肺阶段的幼虫最容易受到宿主免疫攻击。为了评估这一假设，我们将追求以下具体目标：1）生产和培养幼虫寄生虫制剂。我们将推导出对应于皮肤和肺阶段染色体的分泌和表面膜制备物，并通过二维电泳或MudPIT技术将其分离。2)鉴定和表征具有疫苗潜力的幼虫蛋白。我们将选择凝胶点或液相色谱（LC）馏分进行质谱分析，通过数据库搜索将蛋白质与编码DNA联系起来。3)验证分离的幼虫抗原作为潜在的候选疫苗。我们将以重组蛋白的形式表达幼虫抗原。这些或在DNA构建体中配制的编码序列将用于免疫小鼠以产生抗体，所述抗体将用于探测天然蛋白质制剂并定位起源的寄生虫组织。还将对免疫小鼠进行挑战，以评估候选疫苗的保护潜力。 在这方面，第一个系统的研究幼虫抗原作为疫苗候选人，我们希望确定几种新的抗原，可以纳入多价疫苗。幼虫蛋白质组的部分鉴定也将有助于更好地确定血吸虫病中宿主-寄生虫的相互作用。一种有效的疫苗可以通过降低重复治疗的成本和产生耐药性的风险来改变血吸虫病的控制计划。

DESCRIPTION (provided by applicant): Schistosomiasis infects more than 200 million people worldwide. Only one effective drug against this infection is currently in production. No vaccine currently exists. Research toward development of a vaccine against schistosomiasis is the best long-term defense against propagation of drug-resistant parasites and will permit more efficient and cost-effective mass drug treatment programs. A vaccine is feasible because partial natural immunity develops in humans, and 70-90% protection can be achieved in experimental animals using radiation attenuated larvae. Although significant effort has been made toward identifying schistosome vaccine candidates, the most promising antigens trialed by World Health Organization failed to provide the stipulated minimum of 40% protection in independent tests. This poor efficacy may have occurred because for a number of reasons, but highlight the need for novel approaches to identify and test schistosome vaccine candidate antigens. Our long-term goal is to develop an effective schistosome vaccine for humans. This proposal aims to identify molecules expressed during early migratory phases of infection. Our central hypothesis is that larval secretory and/or surface proteins are essential for successful parasite invasion and survival and are principal targets of immune elimination. This derives from our own and others observations that skin-and lung-stage larvae are most vulnerable to host immune attack. To evaluate the hypothesis, we will pursue the following Specific Aims: 1) To generate and fractionate larval parasite preparations. We shall derive secretory and surface membrane preparations corresponding to skin- and lung-stage schistosomes, and fractionate them by 2D electrophoresis or MudPIT technologies. 2) To identify and characterize larval proteins with vaccine potential. We shall select gel spots or liquid chromatography (LC) fractions for analysis by mass spectrometry to link protein to encoding DNA by database searching. 3) To validate isolated larval antigens as potential vaccine candidates. We shall express larval antigens as recombinant proteins. These or coding sequences formulated in a DNA construct will be used to immunize mice to generate antibodies that will be used to probe native protein preparations and to localize the parasite tissue of origin. Immunized mice will also be challenged to assess protective potential of vaccine candidates. In this, the first systematic study of larval antigens as vaccine candidates, we expect to identify several novel antigens that could be incorporated into a multivalent vaccine. Partial identification of the larval proteome will also help to better define host-parasite interaction in schistosomiasis. An effective vaccine could transform control programs for schistosomiasis by reducing the costs of repeated treatment, and the risk of developing drug resistance.