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Relationship of serogroups of Neisseria meningitidis. II. R variants of Neisseria meningitidis
Abstract:
Meningococci isolated in primary cultures from nasopharyngeal carriers occasionally consisted of mixtures of smooth (S) and rough (R) strains. The R strains were separated from the S strains and their morphological and serological characteristics were studied. Some of these R strains reverted spontaneously to S strains which subsequently produced group-specific polysaccharide. Several R strains, grown in the presence of deoxyribonucleic acid from either an R strain of known parentage or an S strain, formed recombinants with serological group specificity.
Insights
Meningococci rough strains can spontaneously revert to smooth strains and form recombinants with specific group characteristics when exposed to deoxyribonucleic acid. This study explores meningococcal strain characteristics and genetic recombination.
Area of Science:
- Microbiology
- Bacteriology
- Genetics
Background:
- Neisseria meningitidis (meningococci) are bacteria that can colonize the nasopharynx.
- Meningococcal isolates from carriers sometimes present as mixed populations of smooth (S) and rough (R) strains.
Purpose of the Study:
- To investigate the characteristics of rough meningococcal strains.
- To explore the potential for genetic recombination and reversion in meningococci.
Main Methods:
- Isolation and separation of rough (R) and smooth (S) meningococcal strains from primary cultures.
- Morphological and serological characterization of R strains.
- Observation of spontaneous R to S strain reversion.
- Experimental recombination assays using deoxyribonucleic acid (DNA) from R and S strains.
Main Results:
- Isolated R strains exhibited distinct morphological and serological properties.
- Some R strains spontaneously reverted to the S phenotype, regaining the ability to produce group-specific polysaccharide.
- Exposure to DNA from other R or S strains induced the formation of recombinants with specific serological group characteristics.
Conclusions:
- Rough meningococcal strains possess the capacity for spontaneous reversion to the smooth phenotype.
- Genetic exchange, evidenced by recombination, can occur between meningococcal strains, leading to altered serological specificities.