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Clinical and Diagnostic Laboratory Immunology, May 1997, 285-290, Vol 4, No. 3
S Narikawa, S Kawai, H Aoshima, O Kawamata, R Kawaguchi, K Hikiji, M Kato, S Iino and Y Mizushima
The nucleic acids of the helical and coccoid forms of Helicobacter pylori
were studied to determine if the coccoid forms are "viable (capable of
growing) but nonculturable." Using a reference strain (NCTC 11638) and five
clinical strains, the nucleic acid contents, DNA integrity, and results of
PCR and reverse transcription-PCR (RT-PCR) were compared for helical H.
pylori and coccoid forms induced using glycochenodeoxycholic acid or
bismuth citrate. The DNA and RNA contents of the coccoid forms were
respectively 6.8- and 8.1-fold lower than those of helical H. pylori after
3 days of induction and 11.5- and 14.7- fold lower after 7 days. Agarose
gel electrophoresis of DNA extracted from the coccoid forms after 3 days of
induction showed a smear pattern indicating DNA cleavage, whereas DNA from
helical H. pylori showed a single band with a high molecular mass. After 12
days of induction, all RNA samples from 100% coccoid cultures were negative
for the mRNA of urease A or the 26-kDa species-specific protein by RT-PCR.
However, most RNA samples obtained after 3 or 7 days of induction were
positive at low levels despite the lack of recovery from these cultures.
These results suggest that the coccoid form of H. pylori has impaired
genomic DNA and is in the process of cellular degeneration, thus being
still alive but nonincreasable.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Comparison of the nucleic acids of helical and coccoid forms of Helicobacter pylori
Institute of Medical Science and Department of Internal and Laboratory Medicine, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
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