Alpha-like protein 3 (Alp3) (Alp3)

Alpha-like protein 3 (Alp3) is a surface-anchored protein belonging to the alpha-like protein (Alp) family of Streptococcus agalactiae (Group B Streptococcus, GBS). It is a chimeric molecule characterized by a mosaic structure of repetitive domains shared with other family members such as Alpha C and Rib. Alp3 is a key virulence factor that facilitates bacterial adherence to and invasion of host epithelial cells, particularly within the vaginal and cervical mucosa, which is critical for maternal colonization and subsequent neonatal infection. It is also expressed by Streptococcus pyogenes (Group A Streptococcus), where it is commonly referred to as R28. As a highly immunogenic surface antigen, Alp3 is a major target in the development of maternal vaccines designed to provide passive immunity to newborns against GBS-induced sepsis, meningitis, and pneumonia.

Other names

R28Protein R28Alp3 proteinSurface protein Alp3

Induction of protective opsonophagocytic antibodies that prevent bacterial adherence and promote immune clearance.