FIG. 4.

The neisserial capsule is upregulated in response to treatment with sublethal concentrations of LL-37. (A) Verification of transcription induced in N. meningitidis serogroup B strain MC58 by treatment with sublethal concentrations of LL-37 as quantified by real-time RT-PCR. MC58 bacteria were grown to the log phase and then exposed to LL-37 (0 and 5 μM) for 30 or 60 min before RNA was immediately harvested and reverse transcribed to cDNA. Real-time PCR using SYBR green was performed on the capsule genes siaC (NMB0068) and siaD (NMB0067). Expression levels were normalized to that of the housekeeping gene NMB0140 and are expressed as relative copy numbers, with 0 μM LL-37 further normalized to give a relative copy number of 1.0. (B) Strain FAM20 and the capsule-deficient mutant strain were grown to the log phase and then exposed to 0 (−) or 5 (+) μM LL-37 for 60 min before analysis by ELISA to determine the presence of the capsule. * and ** represent statistically significant differences (P ≤ 0.01 and P ≤ 0.05, respectively). OD₄₅₀, optical density at 450 nm.