C5 and infection: To explore the correlation between the developmental cycle of the Chlamydia and the cleavage of C5, the C. trachomatis-HeLa229 cell lysates (MOI=1) collected at 0 h, 12 h, 24 h, 36h and 44 h post-infection were co-incubated with purified C5 (400 nM) for 120 min.