A recombination event involving the duplicate genes encoding for the OMPs HopM and HopN, during human infection, which generated
new alleles of these OMPs [21] is added proof. Conclusion The results obtained in the present study suggest that homB and homA genes may be among the H. pylori OMP coding genes contributing to the mechanisms of H. pylori persistence, and would therefore be implicated in the development of disease. Methods Bacterial strains A total of 455 H. pylori strains isolated from patients with upper gastrointestinal symptoms, from 10 different countries were included in the analysis. Table 4 summarizes the characteristics of the study population. Three H. pylori reference strains were used: 26695 strain (ATCC 700392), carrying one copy of homA gene (HP0710); HPAG1 strain, carrying one copy of homB gene (HPAG1_0695) and J99 strain (ATCC 700824), carrying one copy of each gene, Mocetinostat homA (jhp0649) and homB (jhp0870) [12–14]. Table 4 Distribution of Helicobacter pylori strains included in the study (n = 455), according to the geographical origin, gender and patient’s
age. Origin No. of strains Gender, % male Median age ± SD (years) Western countries Portugal 115 47.3 51.8 ± 15.4 France 35 82.9 47.7 ± 14.1 Sweden 27 58.8 66.6 ± 11.2 Germany 20 50.0 58.6 this website ± 11.9 USA 29 67.9 48.7 ± 12.0 Brazil 56 52.4 52.8 ± 16.4 Colombia 19 57.9 50.0 ± 12.7 East Asian countries Japan 72 57.9 44.3 ± 12.7 South Korea 71 76.1 44.7 ± 9.9 African country Burkina Faso 11 N.A. N.A. No., number SD, standard deviation N.A. not available H. pylori strains were cultured from gastric biopsies on agar supplemented with 10% horse blood, preserved in Trypticase Rolziracetam soy broth supplemented with 20% Glycerol and maintained at -80°C until used. Genomic DNA was extracted from a 48 h culture, using the QIAamp DNA mini kit (Qiagen GmbH, Hilden,
Germany), according to the manufacturer’s instructions. Genotyping of homB and homA by PCR and sequencing A single PCR assay was used to discriminate between the homB and homA genes (fragments of 161 bp and 128 bp, respectively) [8]. In order to study the diversity of homB and homA genes, PCR primers find more targeting a conserved region of the flanking genes of both loci jhp0649 and jhp0870, according to the numbering of the J99 strain [13], were designed for amplification of the entire genes [8]. The fragments were subsequently sequenced using the PCR primers and internal primers, as previously described [8]. Sequence analysis and phylogeny Similarity plots, using SimPlot Version 3.5.1 http://sray.med.som.jhmi.edu/SCRoftware, were based on multiple alignments of the full nucleotide sequences of homB and homA genes generated by the BioEdit Sequence Alignment Editor (Version 7.0.1) [35]. Nucleotide sequences were translated using Translate Nucleic Acid Sequences software [36]http://biotools.umassmed.edu/cgi-bin/biobin/transeq.