Molecular biological analysis of pathogenesis of Chlamydia psittaci

鹦鹉热衣原体（Chlamydia psittaci）是一种专性胞内致病微生物，其致病机制包括从隐性潜伏感染到致死性全身感染。其发病机制的分子基础尚未解决。本课题旨在揭示鹦鹉热病原菌致病的分子机制。首先，我们通过比较的方法研究了表达发病机制的关键分子。对几种抗原进行测序以进行结构比较。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型超敏反应的抗原。GroEL基因序列显示了与寄主向性有关的特征。另一种分子是主要外膜蛋白（MOMP）。测序结果表明，不同种衣原体和不同生物群间MOMP基因突变率存在差异，提示MOMP在不同种衣原体和不同生物群间的免疫应答中具有不同的功能和作用。猫衣原体病的血清流行病学研究表明，衣原体病存在于日本的猫。此外，血清学反应性表明猫菌株的血清学变异性。由于分子生物学分析表明MOMP具有同源性，因此猫型特异性抗原可能是MOMP以外的其他分子。这些结果表明，在不同种属和不同生物群中起重要致病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.