Safety and immunogenicity of the group B streptococcus vaccine AlpN in a placebo-controlled double-blind phase 1...

Area of Science:

• Microbiology
• Vaccinology
• Immunology

Background:

• Group B Streptococcus (GBS) causes severe neonatal infections and adverse pregnancy outcomes.
• Alpha-like proteins (Alps) are key GBS surface proteins, with most strains expressing at least one Alp allele.
• Previous GBS vaccine (GBS-NN) showed safety and immunogenicity but targeted limited Alp domains.

Purpose of the Study:

• To assess the safety and immunogenicity of a second-generation GBS vaccine (AlpN) in healthy non-pregnant women.
• To evaluate AlpN's ability to elicit antibody responses against multiple clinically relevant Alp proteins.
• To determine if AlpN vaccination enhances opsonophagocytic killing of GBS strains expressing targeted Alps.

Main Methods:

• Phase I, randomized, double-blind, placebo-controlled, parallel-group study.
• Involved 60 healthy non-pregnant women.
• Assessed safety, antibody titers, and opsonophagocytic activity post-vaccination.

Main Results:

• AlpN vaccine was well tolerated in participants.
• Robust and persistent antibody responses were observed against all four targeted Alp N-terminal domains.
• Vaccination resulted in enhanced opsonophagocytic killing of GBS strains expressing the vaccine targets.

Conclusions:

• The AlpN vaccine is safe and immunogenic in healthy non-pregnant women.
• AlpN elicits broad antibody responses against key GBS Alps, suggesting potential for improved GBS prevention.
• Further studies are warranted to confirm efficacy in preventing GBS infections during pregnancy and in neonates.