Molecular biological analysis of pathogenesis of Chlamydia psittaci

鹦鹉热衣原体是一种专性细胞内病原微生物，其发病机制多种多样，从隐性感染到致死性全身感染。其发病机制的分子基础尚不清楚。本课题旨在揭示鹦鹉热致病性的分子机制。首先，我们用比较的方法研究了表达发病机制的关键分子。对几种抗原进行了结构比较测序。其中最重要的是GroEL，因为GroEL是一种引起沙眼衣原体感染迟发性超敏反应的抗原。GroEL序列显示了与宿主趋向性相关的特征。另一个分子是主要的外膜蛋白（MOMP）。测序结果显示，MOMP基因在衣原体物种和不同生物变种之间的突变率存在差异，表明MOMP在不同物种和不同生物变种中具有不同的免疫应答功能和作用。猫衣原体病血清流行病学研究表明日本猫存在衣原体病。此外，血清学反应性显示了猫株的血清学变异性。猫株的型特异抗原可能不是MOMP，因为分子分析表明MOMP具有同质性。这些结果表明，在不同的物种和不同的生物变体中，在致病性中起重要作用的分子是不同的。

Chlamydia psittaci is an obligately intracellular pathogenic microorganism, which shows a variety of pathogenesis including from an inapparent latent infection to lethal systemic infection. Molecular basis of its pathogenesis is not resolved yet. In this project we tried to reveal molecular mechanism of pathogenicity of C.psittaci. At first we investigated key molecules to express pathogenesis by comparative approach. Several antigens were sequenced for structural comparison. Most important one was a GroEL,because GroEL was an antigen causing delayd hypersensitivity in C.trachomatis infection. Sequences of GroEL indicated characteristics related to host tropism. The other molecule was a major outer membran protein (MOMP). Sequences indicated a variation of mutation rates of MOMP gene among Chlamydial species and biovars, that suggested different functions and roles in immuno responce of MOMP in each species and biovars. Seroepidemiological study of feline chlamydiosis indicated the presence of chlamydiosis in cats of Japan. Furthermore serological reactivity suggested the serological variability of feline strains. Type specific antigen of feline strains may be other molecules than MOMP because molecular analysis indicated the homogeneity of MOMP.These results indicated that molecules playing important roles in pathogenicity were different in each species and biovars related to their pathogenesis.