Analysis of Polymorphic Membrane Protein Expression in Cultured Cells Identifies PmpA and PmpH of <i>Chlamydia psittaci</i> as Candidate Factors in Pathogenesis and Immunity to Infection

The polymorphic membrane protein (Pmp) paralogous families of Chlamydia trachomatis, Chlamydia pneumoniae and Chlamydia abortus are putative targets for Chlamydia vaccine development. To determine whether this is also the case for Pmp family members of C. psittaci, we analyzed transcription levels, protein production and localization of several Pmps of C. psittaci. Pmp expression profiles were characterized using quantitative real-time PCR (RT-qPCR), immunofluorescence (IF) and immuno-electron microscopy (IEM) under normal and stress conditions. We found that PmpA was highly produced in all inclusions as early as 12 hpi in all biological replicates. In addition, PmpA and PmpH appeared to be unusually accessible to antibody as determined by both immunofluorescence and immuno-electron microscopy. Our results suggest an important role for these Pmps in the pathogenesis of C. psittaci, and make them promising candidates in vaccine development.沙眼衣原体（Chlamydia trachomatis）、肺炎衣原体（Chlamydia pneumoniae）与流产衣原体（Chlamydia abortus）的多态膜蛋白（polymorphic membrane protein, Pmp）旁系同源家族，均为衣原体疫苗研发的潜在靶点。为探究鹦鹉热衣原体（C. psittaci）的Pmp家族成员是否同样可作为疫苗研发靶点，本研究对该菌的数种Pmp的转录水平、蛋白表达及定位情况进行了分析。我们采用实时荧光定量聚合酶链式反应（quantitative real-time PCR, RT-qPCR）、免疫荧光（immunofluorescence, IF）与免疫电子显微镜（immuno-electron microscopy, IEM），在正常与应激培养条件下对Pmp的表达谱进行了表征。结果显示，在所有生物学重复实验中，PmpA早在感染后12小时（hpi）即可在所有包涵体中高水平表达。此外，通过免疫荧光与免疫电子显微镜检测发现，PmpA与PmpH对抗体的可及性异乎寻常地高。本研究结果表明，上述Pmp在鹦鹉热衣原体的致病过程中发挥重要作用，同时使其成为疫苗研发的极具前景的候选靶点。