Effects of 405 nm irradiance on chlamydial growth in HeLa cells. (A) HeLa cells were infected with C. trachomatis serovar E at a MOI of 5. (B) Infected cells were then exposed to varying doses of 405 nm at a range of energy densities (5-20 J/cm2) either promptly after infection or 24 h post-infection (24 h post). Treatments are grouped based on post-hoc comparisons for convenience. The effect of 405 nm on chlamydial growth was assessed during active and persistent stages induced with penicillin (B and C). Growth was determined using quantitative real-time PCR to determine the ratio of chlamydial and eukaryotic housekeeping genes (16S: GAPDH respectively) 48 h post-infection on cDNA reverse transcribed from RNA. Mean ± standard deviation are plotted for the two replicated experiments. Statistical significance was determined post-hoc using a Bonferonni adjustment comparing all groups against C. trachomatis-infected HeLa cells alone (CTE); * P < 0.05, ** P < 0.005.