Genetic analysis of mechanisms of chlamydial immune evasion

描述（由申请人提供）：沙眼衣原体性传播感染率稳定或增加，这些感染的后果每年导致数十亿美元的医疗费用。针对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有限理解阻碍了这一目标的进展。衣原体的基因组较小且高度保守。这些病原体如何绕过免疫系统，靶向它们的首选组织并引起疾病尚不清楚。我们的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的衣原体属的组织和宿主的类型。感染可能存在于一个可变的基因组区域称为可塑性区（PZ）。人们怀疑这些PZ基因抵消了由细胞因子IFN-γ控制的宿主细胞防御。其他结果表明C.沙眼临床分离株也有助于免疫逃避和疾病的严重性。我们最近开发了基因工具，现在可以测试这些假设。在我们的第一个目标中，我们将使用反向遗传方法来检测突变体对IFN-γ是否敏感，或者在致病性方面是否有其他改变。 使用易处理的小鼠模型进行体外和体内研究。在目标二中，我们将使用无偏诱变和正向遗传筛选来鉴定有助于逃避IFN-γ的衣原体基因。最后，横向基因转移，表型筛选和基因组测序将用于确定基因组多态性，决定衣原体IFN-<$敏感性在动物和人类。公共卫生相关性：我们的研究将确定决定衣原体病原多样性和毒力的基因，并可能改进用于研究人类衣原体疾病的动物模型。这些数据也可以为构建有效的抗衣原体疫苗提供信息。 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遗传修饰，以确定它们如何避开宿主的免疫系统并引起疾病。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.