Protective Immunity to Human Cholera in Bangladesh

描述(由申请人提供)：该项目是马萨诸塞州总医院-哈佛医学院和孟加拉国国际腹泻疾病研究中心(ICDDR，B)的合作项目，重点是定义对霍乱弧菌感染的保护性免疫并开发改进的霍乱疫苗。该项目的中心假设是霍乱弧菌在早期感染期间表达特定的蛋白质，这些蛋白质产生免疫反应，对随后的暴露具有保护作用；辅助假设是，这些蛋白质在与现有疫苗株的定植过程中没有充分表达，这些差异可能解释了当前疫苗效力降低的原因。这个项目有五个具体目标。在具体目标1中，调查人员将利用粪便和呕吐物样本中微阵列的基因表达谱以及这些样本的蛋白质组学分析，确定孟加拉国人感染霍乱弧菌期间表达的基因和蛋白质。在具体目标2中，研究人员将确定在人类感染霍乱弧菌后以及在接种霍乱疫苗株秘鲁-15之后具有免疫原性的蛋白质，以确定野生型霍乱弧菌和秘鲁-15之间的基因表达差异是否可能与特异性免疫反应的差异有关。在具体目标3中，调查人员将评估霍乱和秘鲁-15疫苗接种后对关键霍乱抗原的免疫持续时间，为期一年的随访期。免疫持续时间将在血清、粪便和十二指肠活检中进行评估，并使用一种新描述的方法来测量循环中的抗原特异性记忆B细胞。在具体目标4中，研究人员将检查在家庭接触霍乱弧菌后，对体内表达的蛋白的哪些免疫反应是保护性的，方法包括：血清和粪便中关键抗原的基线抗体滴度；基线到第3天免疫反应的增加(作为记忆反应的标志)，以及基线时循环中的抗原特异性记忆B细胞的数量。在具体目标5中，调查人员将评估选定的宿主因素与霍乱或秘鲁-15疫苗接种后免疫反应的发展以及与家庭接触后接触有症状的霍乱的易感性的相关性。该项目的长期目标是为改进的霍乱预防疫苗奠定理论基础，并在ICDDR，B完成大量的技术转让和能力建设。

DESCRIPTION (provided by applicant): This project is a collaboration between Massachusetts General Hospital-Harvard Medical School and the International Centre for Diarrheal Disease Research in Bangladesh (ICDDR,B), focused on defining protective immunity to V. cholerae infection and developing an improved cholera vaccine. The central hypothesis of this project is that V. cholerae expresses specific proteins during early infection, which generate immune responses that are protective on subsequent exposure; an ancillary hypothesis is that these proteins are not adequately expressed during colonization with available vaccine strains, and that these differences may explain the lessened efficacy of current vaccines. There are five specific aims in this project. In Specific Aim 1, the investigators will determine the genes and proteins expressed during human infection with V. cholerae in Bangladesh, utilizing gene expression profiling by microarray in samples of stool and vomit, as well as proteomic analysis of these samples. In Specific Aim 2, the investigators will identify proteins that are immunogenic following human infection with V. cholerae, as well as following vaccination with cholera vaccine strain Peru-15, in order to determine whether differences in gene expression between wild-type V. cholerae and Peru-15 may be correlated with differences in specific immune responses. In Specific Aim 3, the investigators will assess the duration of immunity to key cholera antigens following both cholera and Peru-15 vaccination over a 1-year followup period. The duration of immunity will be evaluated in serum, feces, and duodenal biopsies, as well as with a newly described methodology for measuring circulating, antigen-specific memory B cells. In Specific Aim 4, the investigators will examine which of the immune responses to in vivo-expressed proteins are protective following exposure to V. cholerae in household contacts utilizing: baseline antibody liters to key antigens in serum and feces; the increase in baseline to day 3 immunologic responses (as a marker of an anamnestic response), and the number of circulating, antigen-specific memory B cells at baseline. In Specific Aim 5, the investigators will evaluate selected host factors for correlation with development of immune responses following cholera or Peru-15 vaccination, as well as with susceptibility to symptomatic cholera following exposure in household contacts. The long term goals of this project are to develop the theoretical underpinnings for an improved vaccine for prevention of cholera, and to accomplish substantial technology transfer and capacity building at the ICDDR,B.