4% agar (Wako Pure Chemical Industries, Osaka, Japan) containing vancomycin (10 μg/ml) (Brucella plate) at 37°C under microaerophilic

conditions as previously described (21). Bacterial growth was measured by determining the OD at 600 nm (OD600) with a spectrophotometer (GE Healthcare Bio-Science, Piscataway, NJ, USA) and CFU were determined for bacterial viability, when appropriate. The gDNA of HPK5 extracted by the QIAamp DNA Mini kit (Qiagen GmbH, Hilden, Germany) was subjected to PCR with primers specific to babA2 (babA2-Fnc1, 5′-GAAAAAACATGAAAAAACACATCCTTTCAT-3′ and babA2-Rmn2, 5′-TCTGGGTTAATGGCTTGCC-3′) and sabA (sabA-F, 5′-GGCTATCAAATCGGCGAAGC-3′ and sabA-R, find more 5′-GAGATACACGCTATAGAGCC-3′) according to the following click here conditions: for babA2, preheat for 5 min at 94°C, followed by 40 cycles at 94°C for 30 s, 49°C for 30 s, and 72°C for 1 min, and 72°C for 5 min. For sabA, the former conditions were changed by adding the extension steps of 43°C for 30 s at annealing and 72°C for 2 min. The amplicons of babA2 and sabA were cloned into the pGEM-T-Easy vector (Promega, Madison, WI, USA) to produce pBAH and pSAH, respectively. The cloned plasmids, pBAH and pSAH, purified with the QIAprep Spin Miniprep kit (Qiagen GmbH), were employed for analyzing the sequences of these fragments using a BigDye Terminator v1.1 Cycle Sequencing kit and Applied Biosystems

3130 Genetic Analyzer (Applied Biosystems, Foster, CA, USA) to compare the corresponding

sequences of babA2 (HP1243 and jhp0833) and sabA (HP0725 and jhp0662). The kanamycin resistance (kan) cassette (1.0-kb) of pUC4K Vitamin B12 (GE Healthcare Bio-Science), digested with BamHI restriction enzyme, was ligated to the BclI site of the babA2 and sabA fragments in the plasmids, pBAH and pSAH, to construct pBAH-kan and pSAH-kan, respectively. The purified DNA of pBAH-kan or pSAH-kan were utilized as donor DNA to obtain babA2- or sabA-disrupted isogenic mutants of HPK5, HPK5BA2 and HPK5SA4, respectively, by allelic exchange mutagenesis as previously described (20). The disruption of either babA2 or sabA genes by kan cassette in the mutant strains was confirmed by PCR. Furthermore, reverse-transcription PCR (Toyobo, Osaka, Japan) using mRNA extracted from both disrupted mutants with TRIzol reagent (Invitrogen, Carlsbad, CA, USA) confirmed the absence of babA2 or sabA transcripts in the mutant strains. Bacterial labeling with FITC (Sigma) was carried out according to a previous report (22), with modifications. Briefly, H. pylori was cultivated in Brucella broth for 24 hr, corresponding to the late exponential to early stationary phases, and then 1 ml of the bacterial culture broth (OD600= 1.0) was centrifuged (7000 rpm) for 5 min to harvest the bacterium. The bacterial cells were suspended well with 1 ml of PBS including 0.1 μg of FITC at a final concentration of 0.