RFLP and RAPD analysis of in vivo genetic interactions between strains of Helicobacter pylori

Background. The nature of the in vivo interactions between co-colonizing st rains of Helicobacter pylori has not been well studied. This study was desi gned to investigate the in vivo interaction between strains of H. pylori us ing restriction fragment length polymorphism analysis (RFLP) and random amp lified polymorphic DNA fingerprinting (RAPD) analysis. Materials and Methods. Mice were orally inoculated with either a single str ain or a mixture of strains, and killed at various time intervals up to 12 months after inoculation. Results. Inoculum and recovered bacteria were identified by RAPD and RFLP. After 12 months of colonization bacteria recovered from mice given a single strain were identical to the inoculum. In contrast, bacteria recovered fro m mice given a mixture of strains developed minor but consistent difference s in their RAPD patterns. This variation occurred in spite of the fact that only single strains were recovered from mice given a mixture of strains. Conclusion. These findings support the development of genetic heterogeneity of H. pylori during long-term colonization either by genetic drift or by i n vivo recombination. Such genomic modification in vivo could explain the n aturally occurring heterogeneity of H. pylori.