Gamma-Irradiated Non-Capsule Group B Streptococcus Promotes T-Cell Dependent Immunity and Provides a Cross-Protective...

Area of Science:

• Immunology
• Microbiology
• Vaccinology

Background:

• Group B Streptococcus (GBS) is a major cause of neonatal sepsis and pneumonia, with increasing disease burdens in adults.
• Current intrapartum antibiotic prophylaxis (IAP) is insufficient to curb rising GBS infection rates.
• Inactivating GBS via gamma radiation preserves antigenicity while eliminating replication, offering a potential vaccine strategy.

Purpose of the Study:

• To evaluate the immunogenicity and protective efficacy of gamma radiation-inactivated GBS (Rad-GBS) compared to formalin-inactivated GBS (Che-GBS).
• To assess the potential of Rad-GBS as a universal vaccine candidate against invasive GBS infections.

Main Methods:

• GBS strains were inactivated using gamma radiation (Rad-GBS) or formalin (Che-GBS).
• Immunogenicity was assessed by measuring immune cell responses (BMDCs, CD4+ T cells) and antibody production in mice.
• Protective efficacy was determined through challenge studies with virulent GBS strains and adoptive transfer experiments.

Main Results:

• Rad-GBS demonstrated superior immunogenicity compared to Che-GBS, inducing higher expression of costimulatory molecules and stronger CD4+ T cell responses (IFN-γ+, IL-17A+).
• Mice immunized with Rad-GBS showed significant protection against GBS challenge, mediated by antibodies and T cells.
• Rad-GBS induced cross-protection against multiple GBS serotypes, evidenced by enhanced opsonophagocytic killing activity.

Conclusions:

• Gamma radiation is an effective method for inactivating GBS while preserving key antigenic epitopes for vaccine development.
• Rad-GBS elicits robust cellular and humoral immune responses, providing significant protection against invasive GBS disease.
• Inactivated whole-cell GBS vaccines represent a viable strategy for developing universal vaccines against GBS infections.