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上升，这些感染的后果每年造成数十亿美元的医疗费用。我们需要针对这些病原体的疫苗，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。衣原体基因组很小且高度保守。这些病原体是如何绕过免疫系统，瞄准它们喜欢的组织并引起疾病的，目前尚不清楚。我们的知识存在空白的一个主要原因是，这些病原体无法在基因上进行操纵。许多决定不同衣原体感染的组织和宿主类型的基因可能位于一个称为可塑性区（PZ）的可变基因组区域。怀疑这些PZ基因抵消了由细胞因子IFN-¿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有助于免疫逃避和疾病严重程度。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灭活PZ基因，并测试突变体是否对IFN-¿敏感，或者在致病性上有其他改变

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.