Related Experiment Video
Updated: Aug 4, 2026
Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature
Published on: April 1, 2014
Generation and characterization of a plasminogen-binding group A streptococcal M-protein/streptokinase-sensitive
Yetunde A Ayinuola1, Deborah L Donahue1, Jermilia Charles1
1W. M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana, USA.
Background:
Streptococcus pyogenes (GAS) is a human bacterial pathogen that generates various mild to severe diseases. Worldwide, there are approximately 700 million cases of GAS infections per year. In some strains of GAS, the surface-resident M-protein, plasminogen-binding group A streptococcal M-protein (PAM), binds directly to human host plasminogen (hPg), where it is activated to plasmin through a mechanism involving a Pg/bacterial streptokinase (SK) complex as well as endogenous activators. Binding to Pg and its activation are dictated by selected sequences within the human host Pg protein, making it difficult to generate animal models to study this pathogen.
Objectives:
To develop a murine model for studying GAS infection by minimally modifying mouse Pg to enhance the affinity to bacterial PAM and sensitivity to GAS-derived SK.
Methods:
We used a targeting vector that contained a mouse albumin-promoter and mouse/human hybrid plasminogen cDNA targeted to the Rosa26 locus. Characterization of the mouse strain consisted of both gross and histological techniques and determination of the effects of the modified Pg protein through surface plasmon resonance measurements, Pg activation analyses, and mouse survival post-GAS infection.
Results:
We generated a mouse line expressing a chimeric Pg protein consisting of 2 amino acid substitutions in the heavy chain of Pg and a complete replacement of the mouse Pg light chain with the human Pg light chain.
Conclusion:
This protein demonstrated an enhanced affinity for bacterial PAM and sensitivity to activation by the Pg-SK complex, making the murine host susceptible to the pathogenic effects of GAS.
Insights
Researchers developed a new mouse model to study Streptococcus pyogenes infections. This model enhances plasminogen binding and activation, making mice susceptible to GAS, aiding in infection research.
Area of Science:
- Microbiology
- Immunology
- Pathogen Research
Background:
- Streptococcus pyogenes (GAS) causes millions of infections globally.
- GAS M-protein (PAM) binds and activates human plasminogen (hPg), complicating animal model development.
- Plasminogen (Pg) binding and activation are key to GAS pathogenesis.
Purpose of the Study:
- To create a murine model for studying GAS infection.
- To enhance mouse plasminogen (Pg) affinity for bacterial PAM and sensitivity to GAS streptokinase (SK).
Main Methods:
- Generated a mouse line with a chimeric Pg protein (mouse/human hybrid) at the Rosa26 locus.
- Utilized surface plasmon resonance, Pg activation assays, and survival studies.
- Modified mouse Pg with 2 amino acid substitutions and human light chain replacement.
Main Results:
- Created a mouse line expressing a chimeric Pg protein.
- The modified Pg exhibited increased affinity for bacterial PAM.
- Enhanced sensitivity to Pg-SK complex activation was observed.
Conclusions:
- The developed mouse model is susceptible to GAS pathogenic effects.
- This model facilitates the study of GAS infection mechanisms.
- Minimal modification of mouse Pg enables a viable infection model.
