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Interspecies recombination in nature: a meningococcus that has acquired a gonococcal PIB porin
J A Vázquez1, S Berrón, M O'Rourke
1School of Biological Sciences, University of Sussex, Brighton, UK.
Abstract:
A vaginal isolate of Neisseria has been reported to resemble Neisseria meningitidis in biochemical characteristics but to react with serological reagents that are specific to the PI porin from Neisseria gonorrhoeae. We have confirmed that this isolate has the biochemical attributes of a meningococcus and have shown that it clusters among meningococcal isolates on a dendrogram based on isoenzyme variation within housekeeping enzymes from populations of N. meningitidis and N. gonorrhoeae. Furthermore, the sequences of the fbp and adk genes were typical of those of N. meningitidis and were distinct from those of N. gonorrhoeae. However, the porB gene was very similar to the por genes of N. gonorrhoeae isolates that express the PIB class of outer-membrane porin (differing from one gonococcal por allele at only a single nucleotide site), and was clearly distinct from the porB genes of N. meningitidis. The isolate therefore appears to be a typical meningococcus, except that its porB gene has been replaced with the por gene from a gonococcus.
Insights
A unique Neisseria isolate, biochemically a meningococcus (Neisseria meningitidis), possesses a gonococcal (Neisseria gonorrhoeae) porB gene. This finding highlights potential genetic exchange between these bacterial species.
Area of Science:
- Microbiology
- Bacterial Genetics
- Molecular Epidemiology
Background:
- Neisseria meningitidis and Neisseria gonorrhoeae are significant human pathogens.
- Distinguishing between Neisseria species is crucial for diagnosis and treatment.
- Outer membrane porins play a role in Neisseria pathogenesis and immune evasion.
Purpose of the Study:
- To characterize a Neisseria isolate with mixed biochemical and serological properties.
- To investigate the genetic basis for the observed phenotypic characteristics.
- To determine the phylogenetic relationship of the isolate to Neisseria meningitidis and Neisseria gonorrhoeae.
Main Methods:
- Biochemical characterization of the Neisseria isolate.
- Isoenzyme analysis and dendrogram construction for phylogenetic comparison.
- Gene sequencing of housekeeping genes (fbp, adk) and the porB gene.
Main Results:
- The isolate exhibited biochemical characteristics consistent with Neisseria meningitidis.
- Phylogenetic analysis based on isoenzyme variation clustered the isolate with Neisseria meningitidis.
- Sequencing revealed Neisseria meningitidis-like fbp and adk genes, but a Neisseria gonorrhoeae-like porB gene.
Conclusions:
- The isolate is a typical Neisseria meningitidis strain that has acquired the porB gene from Neisseria gonorrhoeae.
- This suggests horizontal gene transfer of the porB gene between Neisseria species.
- The findings have implications for understanding Neisseria evolution and potential mechanisms of immune evasion.