Figure 2.

Effect of indole or tryptophan on the growth of C. trachomatis reference serovars A, D, I, and L2 cultured in the presence of IFN-γ. HeLa cell monolayers were infected with EBs at an moi of 3–5 IFUs/cell. For serovar L2 but not A, D, or I, HeLa cell monolayers were pretreated with IFN-γ (5 ng/ml) for 24 hours before infection. Infected HeLa cells were cultured in the presence of complete DMEM-10 (+Trp), complete DMEM-10 plus 5 ng/ml IFN-γ (+IFN), complete DMEM-10 plus IFN-γ and 100 μM indole (IFN+Ind), and complete DMEM-10 plus IFN-γ and supplemented with 1 g/l tryptophan (IFN+Trp). After 48 hours for serovar L2 and 72 hours for serovars A, D and I, infected cells and culture supernatants were collected and used to infect a new HeLa cell monolayer for enumeration of recoverable IFUs. Data are presented as IFUs (log₁₀) and represent the means ± SD of triplicate determinations.