The role of wcjE disruption in pneumococcal serotype 11A humoral escape

描述（由申请人提供）：肺炎链球菌（肺炎球菌）作为人类病原体的成功主要是由于其能够利用多糖（PS）胶囊来避免宿主免疫。最近的发现和表征的肺炎球菌血清型11 E强烈建议，胶囊合成基因wcjE 8，编码一个假定的O-乙酰转移酶的失活，在逃避宿主的体液免疫反应密切相关的血清型11 A中起着重要的作用。由于许多流行病学流行的血清型也包含该基因，辨别WcjE介导的可变O-乙酰化对血清型11 A和11 E的血清学性质的影响将有助于理解肺炎球菌病理学，确定新出现的肺炎球菌血清型的趋势和设计有效的基于PS的疫苗。 以前的血清型为11 A，11 E的真正流行病学性质尚不清楚。将使用血清特异性单克隆抗体对最初血清型为11 A的临床分离株进行重新修饰，以表达11 E荚膜。为了了解这些血清型的血清学灵活性，将进一步研究导致11 A和11 E之间血清转换的遗传特性。 此外，将使用体外调理吞噬杀伤试验（OPKA），使用接种23价多糖疫苗（包括11 A PS）的人血清，评价wcjE灭活在避免人体液应答中的作用。将比较表达11 A和11 E荚膜的菌株的独立和竞争性OPKA存活，并测定纯化的11 A和11 E PS抑制功能性抗体的能力。 最后，将在鼠感染模型中验证血清型11 A通过体内wcjE失活逃避11 A特异性体液应答的能力以及对病理学的影响。将在未处理条件下、被动11 A特异性免疫以及针对11 A和11 E PS的预免疫下比较11 A和11 E菌株的存活。这些试验还将提供关于使用11 E作为针对两种血清型的潜在疫苗的初步信息。

DESCRIPTION (provided by applicant): The success of Streptococcus pneumonia (pneumococcal) as a human pathogen is largely due to its capability to employ a polysaccharide (PS) capsule to avoid host immunity. Recent discovery and characterization of the pneumococcal serotype 11E strongly suggested that inactivation of the capsule synthesis gene wcjE8 which encodes a putative O-acetyltransferase, plays an important role in escaping a host humoral immune response to the closely related serotype 11A. Since many epidemiologically prevalent serotypes also contain the gene, discerning the effects of WcjE-mediated variable O-acetylating on the serological properties of serotypes 11A and 11E will aid in understanding pneumococcal pathology, in determining trends of emerging pneumococcal serotypes and in designing effective PS-based vaccines. Previously serotype as 11A, the true epidemiological nature of 11E is unclear. Clinical isolates originally serotype as 11A will be readdressed for the expression of 11E capsule using serospecific monoclonal antibodies. To understand the serological flexibility of these serotypes, the genetic properties that lead to seroswitching between 11A and 11E will be further studied. Additionally, the role wcjE inactivation plays in avoiding a human humoral response will be evaluated using an in vitro opsonophagocytosis killing assay (OPKA) with sera from humans vaccinated with the 23- valent polysaccharide vaccine, which includes 11A PS. Independent and competitive OPKA survival of strains expressing 11A and 11E capsule will be compared, and the capacity of purified 11A and 11E PS to inhibit functional antibodies will be determined. Finally, the capacity of serotype 11A to escape an 11A-specific humoral response through wcjE- inactivation in vivo and the effects on pathology will be verified in a murine infection model. The survival of 11A and 11E strains will be compared under naove conditions, with passive 11A-specific immunization, and with preimmunization against 11A and 11E PS. These assays will also provide preliminary information on the use of 11E as a potential vaccine against both serotypes.