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Naturally occurring PIA/PIB hybrids of Neisseria gonorrhoeae
M J Gill1, J Jayamohan, M P Lessing
1Department of Medical Microbiology, St. Mary's Hospital Medical School, Paddington, London, UK.
Abstract:
The major outer membrane protein of Neisseria gonorrhoeae, Por, functions as a porin and is thought to occur as one gene with two alleles. The immunologically distinct epitopes of the two subclasses, IA and IB, have allowed the development of serotyping schemes. Clinical isolates of N. gonorrhoeae are believed to express only a single type of Por, either IA or IB. We have encountered two clusters of isolates that react with antibodies to both IA and IB Por. Isolates within the clusters are indistinguishable by the phenotypic characteristics tested. In addition, the amplification of the por gene in representative isolates showed that the por gene of the hybrids gave similar restriction digest patterns within but not between the clusters.
Insights
Two Neisseria gonorrhoeae clusters express both IA and IB Por protein types, challenging existing serotyping. These unique bacterial isolates possess distinct por gene restriction patterns within, but not between, the identified clusters.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- Neisseria gonorrhoeae's major outer membrane protein, Por, acts as a porin.
- Por exists as one gene with two alleles (IA and IB), enabling serotyping.
- Clinical isolates typically express only one Por type (IA or IB).
Purpose of the Study:
- To investigate unusual Neisseria gonorrhoeae isolates expressing both IA and IB Por types.
- To characterize these isolates and their por genes.
Main Methods:
- Serological testing using antibodies against IA and IB Por subclasses.
- Phenotypic characterization of clinical isolates.
- Polymerase chain reaction (PCR) amplification of the por gene.
- Restriction fragment length polymorphism (RFLP) analysis of amplified por genes.
Main Results:
- Identified two distinct clusters of N. gonorrhoeae isolates reacting with both IA and IB Por antibodies.
- Isolates within each cluster were phenotypically indistinguishable.
- PCR and RFLP analysis revealed distinct por gene restriction patterns within, but not between, the two clusters.
Conclusions:
- These findings suggest the existence of novel N. gonorrhoeae variants or hybrid strains.
- The distinct por gene patterns indicate genetic divergence within these unusual isolates.
- Further research is needed to understand the implications of dual Por expression for gonococcal pathogenesis and diagnostics.