Related Experiment Video
Updated: Feb 18, 2026
04:25
Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
46.7K
Identification and Characterization of Serotype-Specific Variation in Group A Streptococcus Pilus Expression
Gregory Calfee1, Jessica L Danger1, Ira Jain1
1Department of Microbiology & Immunology, University of Nevada, Reno, School of Medicine, Reno, Nevada, USA.
Infection and Immunity
|November 22, 2017
Summary
Group A Streptococcus (GAS) bacteria show serotype-specific pili expression. Serotype M3 GAS, linked to severe infections, has low pili, aiding blood survival and host adherence reduction.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Phenotypic variation in bacterial pathogens like Group A Streptococcus (GAS; Streptococcus pyogenes) can impact public health and treatment efficacy.
- GAS infections range in severity, with certain serotypes, like M3, disproportionately associated with invasive and lethal outcomes.
- Cell surface structures, such as pili, play critical roles in bacterial-host interactions and virulence.
Purpose of the Study:
- To investigate the role of pili expression in serotype-specific phenotypic variation within Group A Streptococcus (GAS).
- To understand the molecular mechanisms regulating pilus expression in different GAS serotypes, particularly M3.
- To determine the functional consequences of differential pilus expression on GAS virulence and host-pathogen interactions.
Main Methods:
- Comparative analysis of pilus expression across different GAS serotypes (M1, M3, M49).
- Transcriptome comparison between serotype M1 and M3 GAS isolates to identify regulatory differences.
- Investigation of the transcriptional regulator Nra's role in pilus expression in M3 GAS.
Main Results:
- GAS isolates exhibit serotype-specific pilus expression, with serotype M3 producing significantly lower levels compared to M1 and M49.
- The transcriptional regulator Nra positively controls pilus expression in M3 GAS, and its low transcription correlates with reduced pilus levels.
- Low pilus expression in M3 GAS is associated with decreased adherence to host cells but enhanced survival and proliferation in human blood.
Conclusions:
- Serotype-dependent pilus expression is a key feature of GAS, influencing its pathogenic potential.
- Reduced pilus expression in M3 GAS contributes to enhanced survival in blood, potentially explaining its association with severe invasive infections.
- These findings provide insights into GAS virulence mechanisms and may inform the development of novel GAS vaccines targeting pilus proteins.
Related Concept Videos
01:28Fimbriae, Pili, and Axial Filaments
2.2K
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
2.2K
01:28Methods of Classification and Identification
1.3K
Bacterial identification relies on a diverse array of techniques to classify and understand microorganisms, each tailored to uncover specific characteristics. Traditional morphological approaches, while still valuable, are limited for closely related or structurally simple organisms. Modern methods integrate biochemical, serological, genetic, and advanced molecular tools to achieve greater accuracy.Morphological and Biochemical TechniquesMorphological characteristics, such as cell shape and...
1.3K