title: Neutralizing antichlamydial activity of complement by chlamydia-secreted protease CPAF.
abstract: Ascending infection by sexually transmitted Chlamydia trachomatis is required for chlamydial induction of tubal pathology. To achieve ascension, the C. trachomatis organisms may have to spread from cell to cell, which inevitably exposes the organisms to extracellular mucosal effectors such as complement factors that are known to possess strong antichlamydial activities. Here, we report that the chlamydia-secreted protease CPAF efficiently neutralized complement factor C3-dependent antichlamydial activity. The neutralization was dependent on the proteolytic activity of CPAF and correlated with the CPAF-mediated degradation of complement factor C3 and factor B. As a result, CPAF preferentially inhibited the alternative complement activation pathway. The significance and limitation of these observations were discussed.
authors.affiliation: Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
authors.forename: Zhangsheng
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Clinic Diagnosis, Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Lingli
authors.initials: L
authors.lastname: Tang
authors.affiliation: Department of Endocrinology, Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Microbiology & Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA. Electronic address: Zhongg@UTHSCSA.EDU.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhong
mesh_terms: D002692:Chlamydia trachomatis / Q000276:immunology*; D003176:Complement C3 / Q000037:antagonists & inhibitors*; D011415:Complement Factor B / Q000037:antagonists & inhibitors*; D003170:Complement Pathway, Alternative; D010450:Endopeptidases / Q000276:immunology*; D006367:HeLa Cells; D006801:Humans; D057131:Immune Evasion; D007155:Immunologic Factors / Q000037:antagonists & inhibitors*; D059748:Proteolysis
chemical_list: D003176:Complement C3; D007155:Immunologic Factors; D010450:Endopeptidases; D011415:Complement Factor B; C425923:CPA factor
keywords: CPAF; Neutralization of antichlamydial activity; Proteolysis of complement factor C3 & factor B