Three female BALB/c mice were injected intraperitoneally with the bacterial suspension at a volume of 0.5 mL. Twenty-four hours later, the mice were sacrificed, injected intraperitoneally with 1 mL of sterile PBS, kept for 1 min with gentle massage over the abdomen and then extracted. After serial dilution, the samples were spread KU-60019 purchase on the LB plates and incubated at 37 °C overnight.
Of the colonies recovered from the same mice, 20 were randomly picked and identified by PCR with primers O1 and O2. To calculate the competitive indices, the ratio of yncD-deleted mutant to wild type recovered from the abdominal cavity was determined and then normalized by dividing by the ratio of yncD-deleted mutant to wild type in the initial inoculum. Female BALB/c mice aged 6–8 weeks (five groups with three mice per group) were immunized once intranasally with 109 CFU of YGC102 or PBS (as control). Thirty days later, the mice of the control group were challenged with 103 CFU of wild type, whereas the mice of the other four groups were challenged respectively with 104, 105, 106 and 107 CFU of the strain using the porcine gastric mucin model as described TGF-beta inhibitor above. The survival of the mice was monitored for 7 days. A promoterless egfp gene from pEGFP-N2 was isolated by digestion with EcoRI and HindIII
and was subcloned into the corresponding sites of the pBR322 plasmid, resulting in the pBGPL plasmid. The yncD promoter region was amplified by PCR using the primers EPR1 and EPR2 (Table 1). The promoter fragment was ligated directly with PMD18-T vector and subcloned as NcoI fragments into the corresponding sites of pBGPL resulting in the pBGP plasmid. The generated plasmid was electroporated into the YGC101 strain to generate YGC104 strain. The YGC104 strain cells were inoculated into the indicated media (for the heat-shock experiment, cells were incubated at
45 °C for 10 min) and grown at 37 °C for 5 h to allow expression of enhanced green fluorescent protein (EGFP). Then, the bacteria were diluted with PBS and analyzed in a flow Metalloexopeptidase cytometer (BD FACSCanto II) with the gates set to forward and side scatters characteristic of the bacteria. The optical detector FL1-H was used for this measurement. For each condition assessed, 10 000 bacterial cells were analyzed and the mean fluorescent intensity of the bacteria was obtained. Each experiment was performed in triplicate. Comparisons of expression values among the groups were performed by t-test. Total RNA was isolated from bacterial cells of Ty2 wild type incubated under each condition using the SV Total RNA Isolation System (Promega). Additional treatments with RNase-Free DNase I (Takara) were performed to eliminate any genomic DNA. The quantity and quality of the total RNA was determined with an ND-1000 spectrophotometer (NanoDrop). The cDNAs were synthesized using the PrimeScript RT reagent kit (Takara).