Recombinant production platform for Group A Streptococcus glycoconjugate vaccines

Area of Science:

• Microbiology
• Vaccinology
• Biotechnology

Background:

• Group A Streptococcus (Strep A) is a significant human pathogen responsible for over 500,000 deaths annually, with no existing licensed vaccine.
• Strep A possesses a conserved rhamnose polysaccharide (RhaPS) backbone in its surface Group A Carbohydrate, making it a validated universal vaccine target.
• Current vaccine development strategies often involve glycoconjugates, chemically linking carbohydrates to carrier proteins.

Purpose of the Study:

• To engineer the Group A Carbohydrate biosynthesis pathway for recombinant production of RhaPS glycoconjugates.
• To assess the structural integrity and immunogenicity of the recombinantly produced RhaPS glycoconjugates.
• To confirm the potential of these recombinant glycoconjugates as vaccine candidates against Strep A.

Main Methods:

• Engineering the Group A Carbohydrate biosynthesis pathway in Escherichia coli for RhaPS production.
• Recombinant coupling of RhaPS to carrier proteins within E. coli.
• Structural confirmation using Nuclear Magnetic Resonance (NMR) spectroscopy and mass spectrometry.
• Immunization of mice and rabbits with purified RhaPS glycoconjugates.
• Assessment of antibody response and binding to diverse Strep A strains.

Main Results:

• Successful engineering of the RhaPS biosynthesis pathway for recombinant production.
• Confirmation of structural integrity of the recombinant RhaPS glycoconjugates.
• Elicitation of carbohydrate-specific antibodies in immunized animals.
• Demonstrated binding of antibodies to multiple Strep A strains of diverse M-types.

Conclusions:

• Recombinant production of RhaPS glycoconjugates is feasible and maintains structural integrity.
• The produced RhaPS glycoconjugates are immunogenic and elicit specific antibodies.
• These findings validate recombinantly produced RhaPS glycoconjugates as promising vaccine candidates against Strep A.