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Selection for urease activity during Helicobacter pylori infection of rhesus macaques (Macaca mulatta)
1Department of Internal Medicine, University of California, Davis School of Medicine, Davis, California 95616, USA.
Abstract:
Helicobacter pylori strain J166 recovered from experimentally inoculated rhesus monkeys had up to a 250-fold-increased urease activity over that before inoculation. This was found to result from the selection of urease positive J166 clones from a heterogeneous inoculum, which was predominantly urease negative due to a 1-bp insertion in the ureA gene. These results confirm the importance of urease for H. pylori colonization. Strain J166 is particularly well adapted to the rhesus monkey, since it colonized preferentially despite the fact that less than 0.1% of the inoculum was urease positive.
Insights
Helicobacter pylori urease activity significantly increased in rhesus monkeys due to selection of urease-positive clones. This highlights urease
Area of Science:
- Microbiology
- Gastroenterology
- Infectious Diseases
Background:
- Helicobacter pylori is a significant human pathogen.
- Urease is a key virulence factor for H. pylori.
- Strain J166 was used in experimental inoculation of rhesus monkeys.
Purpose of the Study:
- To investigate the changes in urease activity of H. pylori strain J166 after experimental inoculation in rhesus monkeys.
- To determine the genetic basis for observed changes in urease activity.
- To confirm the role of urease in H. pylori colonization.
Main Methods:
- Experimental inoculation of rhesus monkeys with H. pylori strain J166.
- Measurement of urease activity in bacterial isolates.
- Genetic analysis of ureA gene to identify mutations.
Main Results:
- Urease activity increased up to 250-fold in recovered H. pylori J166.
- The increase was due to selection of pre-existing urease-positive clones.
- A 1-bp insertion in the ureA gene rendered most of the inoculum urease-negative.
Conclusions:
- Urease is crucial for H. pylori colonization in vivo.
- Strain J166 demonstrates adaptation to the rhesus monkey host.
- Selection of urease-positive variants is a key mechanism for H. pylori colonization.