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M or M-like protein gene polymorphisms in human group G streptococci
N Schnitzler1, A Podbielski, G Baumgarten
1Institute of Medical Microbiology, Technical University RWTH Aachen, Germany.
Journal of Clinical Microbiology
|February 1, 1995
Summary
Group G streptococci (GGS) from humans carry M-like protein genes homologous to human group A streptococci (GAS) M genes, unlike GGS from animals. This genetic diversity suggests horizontal gene transfer and potential for GGS strain typing.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Group G streptococci (GGS) from human infections share M or M-like proteins with group A streptococci (GAS).
- The genetic basis and diversity of these M-like protein genes (emmL) in GGS require further elucidation.
Purpose of the Study:
- To investigate the polymorphisms of the emmL gene in GGS strains isolated from human and animal sources.
- To compare the genetic features of emmL genes in GGS with those of GAS.
Main Methods:
- Southern blot hybridization using probes for GAS M class I and M class II emm genes.
- Polymerase chain reaction (PCR) amplification of emmL genes from GGS strains.
- DNA sequencing of emmL genes from human-associated GGS isolates.
Main Results:
- All human-associated GGS strains hybridized with the GAS M class I emm gene probe, while animal-associated strains did not.
- emmL genes from human GGS isolates exhibited structural features typical of M class I GAS emm genes.
- Sequencing revealed significant emmL gene diversity in human GGS, with six distinct genetic types identified among 30 strains and unique sequences in the remaining eight.
Conclusions:
- Human-associated GGS possess emmL genes homologous to GAS M genes, suggesting a distinct evolutionary path from animal-associated GGS.
- The observed emmL gene polymorphisms in GGS indicate potential horizontal gene transfer from GAS and offer a basis for molecular subspecies delineation and epidemiological typing.