Construction of a Helicobacter pylori genome map and demonstration of diversity at the genome level

Abstract

Genomic DNA from 30 strains of Helicobacter pylori was subjected to pulsed-field gel electrophoresis (PFGE) after digestion with NotI and NruI. The genome sizes of the strains ranged from 1.6 to 1.73 Mb, with an average size of 1.67 Mb. By using NotI and NruI, a circular map of H. pylori UA802 (1.7 Mb) which contained three copies of 16S and 23S rRNA genes was constructed. An unusual feature of the H. pylori genome was the separate location of at least two copies of 16S and 23S rRNA genes. Almost all strains had different PFGE patterns after NotI and NruI digestion, suggesting that the H. pylori genome possesses a considerable degree of genetic variability. However, three strains from different sites (the fundus, antrum, and body of the stomach) within the same patient gave identical PFGE patterns. The genomic pattern of individual isolates remained constant during multiple subcultures in vitro. The reason for the genetic diversity observed among H. pylori strains remains to be explained.

Pulsed-field gel electrophoresis analysis of the genome of amino acid producing corynebacteria: chromosome sizes and diversity of restriction patterns

“…Some authors (Forbes e t al., 1991 ;Grothues & Tummler, 1991) have claimed that restriction fragment fingerprinting is useful for studying genetic relatedness of different strain isolates, but results with other species such as Helicobacterpylori (Taylor et al, 1992) and Bacillus c6rea.r (Carlson etal., 1992), and also our own results, prove that, at least for groups of very heterogeneous bacteria, the criteria of grouping according to restriction fragment patterns has little taxonomic value. The two B. lactofermentnm strains (and to a lesser degree the C. glzltamiczlm strain) are very closely related from the point of view of biochemical and morphological characteristics, but they represent a heterogeneous family of isolates with different genome structures.…”

A novel tRNA-associated locus (trl) from Helicobacter pylori is co-transcribed with tRNAGly and reveals genetic diversity

“…pylori has been welldocumented, although the mechanisms responsible are as yet undefined (Marshall et al, 1998). At the molecular level, the organism's genetic diversity has been shown by extensive point mutations and mosaic differences in conserved genes (Atherton et al, 1995), the presence or absence of particular loci (Xiang et aZ., 1995;Cao & Cover, 1997) and pathogenicity islands (Censini et al, 1996), and by large-scale chromosomal rearrangements (Taylor et al, 1992;Jiang et al, 1996). The identification of the trl locus in only 50% of clinical isolates tested further confirms the genetic diversity in H .…”

Genotyping of Nigerian Helicobacter pylori isolates by pulsed-field gel electrophoresis

“…pylori infects up to 50 % of the human population worldwide. Tremendous genetic diversity has been reported for H. pylori and Taylor et al (1992) reported that this bacterium possesses a great deal of diversity in genomic DNA restriction profiles when analysed by pulsed-field gel electrophoresis (PFGE); the molecular and epidemiological bases for this phenomenon are not understood.…”

“…pylori infects up to 50 % of the human population worldwide. Tremendous genetic diversity has been reported for H. pylori and Taylor et al (1992) reported that this bacterium possesses a great deal of diversity in genomic DNA restriction profiles when analysed by pulsed-field gel electrophoresis (PFGE); the molecular and epidemiological bases for this phenomenon are not understood.The aim of the study was to compare DNA profiles of H. pylori strains isolated from Lagos and Ife, Nigeria and also to determine if the isolates obtained from the antrum and corpus of the same patient were genotypically similar.Genomic DNA of 41 H. pylori strains isolated from 38 patients was prepared for PFGE, as described previously (Taylor et al, 1992). Six of the 41 isolates were from three patients, from whom biopsies were taken from both the antrum and the corpus.…”

“…Genomic DNA of 41 H. pylori strains isolated from 38 patients was prepared for PFGE, as described previously (Taylor et al, 1992). Six of the 41 isolates were from three patients, from whom biopsies were taken from both the antrum and the corpus.…”