Related Experiment Video
Updated: Mar 6, 2026
Opsonophagocytic Killing Assay to Assess Immunological Responses Against Bacterial Pathogens
Published on: April 5, 2019
Evaluation of the Potency, Neutralizing Antibody Response, and Stability of a Recombinant Fusion Protein Vaccine for
E Burlet1, H HogenEsch2, A Dunham2
1VaxForm, LLC, Bethlehem, Pennsylvania, USA.
Insights
A new recombinant fusion protein vaccine (SpeAB) shows promise for preventing Group A Streptococcus (GAS) infections. The vaccine is stable and elicits neutralizing antibodies against key GAS virulence factors.
Area of Science:
- Microbiology
- Immunology
- Vaccinology
Background:
- Group A Streptococcus (GAS) causes significant global health issues, including pharyngitis and severe invasive diseases.
- There is a critical unmet need for a vaccine to prevent GAS infections, as none are currently licensed.
- GAS virulence is mediated by toxins like streptococcal pyrogenic exotoxin A (SpeA) and streptococcal pyrogenic exotoxin B (SpeB).
Purpose of the Study:
- To evaluate the immunogenicity and stability of a novel recombinant fusion protein vaccine targeting GAS infections.
- To assess the vaccine's ability to induce neutralizing antibodies against major GAS virulence factors.
- To determine the potential of this vaccine to reduce the global burden of GAS disease.
Main Methods:
- Development of a recombinant fusion protein (SpeAB) combining inactive mutant forms of SpeA and SpeB.
- Adsorption of the SpeAB vaccine to an aluminum adjuvant for enhanced immunogenicity.
- Assessment of vaccine immunogenicity, antibody induction, and stability through rigorous testing.
Main Results:
- The SpeAB vaccine demonstrated robust immunogenicity in studies.
- Specific neutralizing antibodies against SpeA and SpeB were successfully elicited.
- Stability studies indicated the vaccine retains immunogenicity for at least two years under refrigeration.
Conclusions:
- The novel SpeAB vaccine is a promising candidate for protection against GAS infections.
- This vaccine has the potential to significantly reduce the global health burden associated with GAS.
- Further development could lead to the first licensed vaccine against Group A Streptococcus.
Abstract:
Streptococcus pyogenes or group A streptococcus (GAS) is a Gram-positive bacterium that can cause a wide range of diseases, including pharyngitis, impetigo, scarlet fever, necrotizing fasciitis, rheumatic fever, and streptococcal toxic shock syndrome. Despite the increasing burden on global health caused by GAS, there is currently no licensed vaccine available. In this study, we evaluated immunogenicity, induction of neutralizing antibodies, and stability of a new recombinant fusion protein vaccine that targets infections from GAS. The recombinant fusion protein (SpeAB) combines inactive mutant forms of streptococcal pyrogenic exotoxin A (SpeA) and streptococcal pyrogenic exotoxin B (SpeB). The SpeAB vaccine evaluated in this study was adsorbed to an aluminum adjuvant and demonstrated robust immunogenicity, eliciting production of specific neutralizing antibodies against SpeA and SpeB, two major virulence factors of S. pyogenes. Stability studies suggest that the vaccine will retain immunogenicity for at least 2 years when stored at refrigerated temperatures. This novel vaccine shows great potential to provide protection against GAS infections and to reduce the burden of GAS disease globally.
