Helicobacter pylori tissue tropism: mouse-colonizing strains can target different gastric niches

Abstract

Studies with the mouse-adapted Helicobacter pylori strain SS1 had supported an idea that infections by this pathogen start in the gastric antrum and spread to the corpus after extensive mucosal damage. This paper shows that the unrelated strain X47 colonizes the corpus preferentially. Differences between strains in preferred gastric region were detected by co-inoculating mice with a mixture of SS1 and X47, and genotyping H. pylori recovered after 2-8 weeks of infection by vacA s allele PCR and RAPD fingerprinting. Mixed infections were found in each of 59 co-inoculated young C57BL/6J mice. On average, however, SS1 was fourfold more abundant than X47 in the antrum and X47 was threefold more abundant than SS1 in the corpus. Similar results were obtained in mice inoculated first with one strain and then the other strain 2 weeks later. SS1 was even more abundant in the antrum of elderly (>1 year old) mice (97 % of isolates). Qualitatively similar SS1 and X47 tissue distributions were seen using unrelated mouse lines (AKR/J, A/J, DBA/2J, BALB/cJ, LG/J, SM/J), but with significantly different SS1 : X47 ratios in some cases. These results suggest the existence of at least two distinct gastric niches whose characteristics may be affected by host genotype and age (physiology), and indicate that strains differ in how effectively they colonize each niche. Differences among gastric regions and the mixed infections that these allow may contribute to H. pylori diversity and genome evolution.

Gut Bacterial Diversity of the House Sparrow (Passer domesticus) Inferred by 16S rRNA Sequence Analysis

“…Inside the intestinal environment, bacteria species can get established as biofilm communities on the surface of the intestinal wall intimately attached to epithelial tissue, deeply embedded in the mucus layer overlaying the villi, free-living in the lumen, or colonizing the crypts and plica at the base of the villi [1,42,47,55]. By using a homogenate of the complete intestine before extracting the DNA, we ensured the presence of bacteria from all the intestinal habitats.…”

Multiplex PCR Assay for Rapid Detection and Genotyping of Helicobacter pylori Directly from Biopsy Specimens

“…The other 10 (24.4%) gave different results, possibly due to multiple H. pylori strains infecting the hosts. Also, because H. pylori colonization in gastric mucosa is often patchy rather than uniform, the separate biopsies used for multiplex PCR and culture may harbor two different strains (1).…”

Helicobacter acinonychis : Genetic and Rodent Infection Studies of a Helicobacter pylori -Like Gastric Pathogen of Cheetahs and Other Big Cats

“…pylori itself is a most genetically diverse species: independent clinical isolates are usually distinguishable by DNA fingerprinting (4) and typically differ from one another by some 2% or more in sequences of essential housekeeping genes and 5% or more in gene content (1,3,5,43). This diversity probably stems from a combination of factors, including (i) mutation (50); (ii) recombination between divergent strains and species (1,5,16,46,47); (iii) selection for host-specific adaptation during chronic infection, which reflects differences between people and also within individual stomachs in traits that can be important to H. pylori (2,11,25,33); and (iv) a highly localized (preferentially intrafamilial) pattern of transmission (22, 38), which promotes genetic drift and minimizes the chance of selection for just one or a few potentially most-fit genotypes.It is not known when H. pylori became human adapted. One theory proposes that its association with humans is truly ancient, that H. pylori infection has been near universal in humans and in our nonhuman primate ancestors for perhaps millions of years (6).…”