title: Genomic changes during chronic Helicobacter pylori infection.
abstract: The gastric pathogen Helicobacter pylori shows tremendous genetic variability within human populations, both in gene content and at the sequence level. We investigated how this variability arises by comparing the genome content of 21 closely related pairs of isolates taken from the same patient at different time points. The comparisons were performed by hybridization with whole-genome DNA microarrays. All loci where microarrays indicated a genomic change were sequenced to confirm the events. The number of genomic changes was compared to the number of homologous replacement events without loss or gain of genes that we had previously determined by multilocus sequence analysis and mathematical modeling based on the sequence data. Our analysis showed that the great majority of genetic changes were due to homologous recombination, with 1/650 events leading to a net gain or loss of genes. These results suggest that adaptation of H. pylori to the host individual may principally occur through sequence changes rather than loss or gain of genes.
authors.affiliation: Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kraft
authors.forename: Allison
authors.initials: A
authors.lastname: Stack
authors.forename: Christine
authors.initials: C
authors.lastname: Josenhans
authors.forename: Eike
authors.initials: E
authors.lastname: Niehus
authors.forename: Guido
authors.initials: G
authors.lastname: Dietrich
authors.forename: Pelayo
authors.initials: P
authors.lastname: Correa
authors.forename: James G
authors.initials: JG
authors.lastname: Fox
authors.forename: Daniel
authors.initials: D
authors.lastname: Falush
authors.forename: Sebastian
authors.initials: S
authors.lastname: Suerbaum
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002908:Chronic Disease; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D044404:Genomic Islands / Q000235:genetics; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori