Genetic analysis of mechanisms of chlamydial immune evasion

描述(由申请人提供)：沙眼衣原体的性传播感染率稳定或上升，这些感染的后果每年导致数十亿美元的医疗费用。这些病原体的疫苗是必要的，但我们对衣原体如何逃避免疫系统的了解有限，阻碍了实现这一目标的进展。衣原体基因组很小，而且高度保守。目前尚不清楚这些病原体是如何规避免疫，针对它们的首选组织并导致疾病的。我们知识差距的一个主要原因是这些病原体不能被基因操纵。许多基因决定了不同衣原体的组织类型和宿主。感染病毒可能存在于一个称为可塑性区域(PZ)的可变基因组区域。据推测，这些PZ基因抵消了由细胞因子干扰素控制的宿主细胞防御。其他结果表明，沙眼衣原体临床分离株核心基因的多态性也与免疫逃避和疾病严重程度有关。我们最近开发了基因工具，现在可以测试这些假说。在我们的第一个目标中，我们将使用反向遗传方法来灭活PZ基因，并测试突变体是否对干扰素敏感，或者在致病性方面有其他变化。 使用易驯服的小鼠模型进行体外和体内实验。在目标二中，我们将使用无偏向突变和正向遗传筛选来识别有助于逃避干扰素的衣原体基因。最后，将使用横向基因转移、表型筛选和基因组测序来确定决定动物和人类中衣原体干扰素敏感性的基因组多态。公共卫生相关性：我们的研究将确定决定衣原体致病多样性和毒力的基因，并可能导致改进研究人类衣原体疾病的动物模型。这些数据还可以为构建有效的抗衣原体疫苗的尝试提供依据。 公共卫生相关性：衣原体属的细胞内细菌是人类病原体，是可预防的失明和性传播感染的常见原因。我们建议对这些病原体进行基因改造，以确定它们如何避开宿主的免疫系统并导致疾病。这项研究的见解将有助于设计可以预防衣原体疾病的疫苗。

DESCRIPTION (provided by applicant): Rates of Chlamydia trachomatis sexually transmitted infection are stable or increasing and consequences of these infections incur billions in medical costs annually. Vaccines for these pathogens are needed but our limited understanding of how chlamydiae evade the immune system has inhibited progress towards this goal. Chlamydial genomes are small and highly conserved. How these pathogens circumvent immunity, target their preferred tissues and cause disease is unknown. A major reason for gaps in our knowledge was that these pathogens could not be genetically manipulated. Many genes that determine the types of tissues and hosts that different Chlamydia spp. infect may reside in a variable genomic region called the plasticity zone (PZ). It is suspected these PZ genes counteract host cell defenses controlled by the cytokine IFN-¿. Other results indicate polymorphisms in core genes of C. trachomatis clinical isolates also contribute to immune evasion and disease severity. We recently developed genetic tools that now make it possible to test these hypotheses. In our first aim, we will use a reverse genetic approach to inactivate PZ genes and test if the mutants are sensitive to IFN-¿, or have other alterations in pathogenicity in vitro and in vivo using a tractable mouse model. In aim two we will use unbiased mutagenesis and forward genetic screens to identify chlamydial genes that contribute to evasion of IFN-¿. Finally, lateral gene transfer, phenotypic screens and genome sequencing will be used to identify genomic polymorphisms that determine chlamydial IFN-¿ sensitivity in animals and humans. Public Health Relevance: Our study will identify genes that determine chlamydial pathogenic diversity and virulence and could lead to improved animal models for study of human chlamydial disease. The data could also inform attempts to construct effective anti-chlamydial vaccines. PUBLIC HEALTH RELEVANCE: Intracellular bacteria in the genus Chlamydia are human pathogens and are common causes of preventable blindness and sexually transmitted infections. We propose to genetically modify these pathogens to determine how they avoid the immune systems of their hosts and cause disease. Insights from this study will help design vaccines that could prevent chlamydial disease.