Alpha-like protein family (Alp family) (Alp family)

The Alpha-like protein (Alp) family is a group of surface-anchored proteins found in Streptococcus agalactiae (Group B Streptococcus, GBS), which is a leading cause of neonatal sepsis and meningitis (Lindahl et al., 2005). This family includes the Alpha C protein, Rib, and Alp1 through Alp4, all of which share a similar structural organization characterized by a conserved N-terminal signal sequence, a large repeat region, and a C-terminal cell wall anchoring motif (Maeland et al., 2015). These proteins play critical roles in bacterial pathogenesis by mediating adhesion to host epithelial cells and facilitating invasion, as well as contributing to immune evasion by interfering with host complement deposition (Bolduc et al., 2002). Because these proteins are highly immunogenic and expressed across most GBS clinical isolates, they are primary targets for the development of protein-based maternal vaccines (Minervax, 2023). Current therapeutic strategies focus on using recombinant N-terminal domains of these proteins to elicit opsonophagocytic antibodies that provide passive immunity to newborns (Fischer et al., 2021). The diversity within the Alp family necessitates multivalent vaccine approaches to ensure broad protection against various GBS strains (Creti et al., 2004).

Other names

Alp proteinsAlpha-antigen familyGroup B Streptococcus surface proteinsAlpha-C-like proteinsBca-like proteins

Induction of opsonophagocytic antibodies that facilitate bacterial clearance by the host immune system (Maeland et al., 2015).