Alpha-like protein (Alp) (Alp)

Alpha-like proteins (Alps) are a family of surface-anchored proteins primarily found in Group B Streptococcus (GBS), also known as Streptococcus agalactiae (Pawlowski et al., 2022). This protein family, which includes members such as Alpha C (encoded by bca), Rib, and Alp1-4, plays a pivotal role in bacterial virulence by mediating adhesion to and invasion of host epithelial cells, particularly in the maternal reproductive tract (Gabrielsen et al., 2017; Maeland et al., 2015). Alps are characterized by a conserved N-terminal domain and a variable number of tandem repeats that contribute to immune evasion and structural diversity (Lindahl et al., 2005). Because they are nearly ubiquitous across clinical GBS isolates and are highly immunogenic, they have become leading targets for the development of maternal vaccines aimed at preventing neonatal sepsis, meningitis, and pneumonia (Banks et al., 2023). Experimental vaccines like GBS-NN utilize recombinant N-terminal domains of these proteins to elicit protective opsonophagocytic antibodies that are transferred across the placenta to the fetus (Pawlowski et al., 2022; Fischer et al., 2021).

Other names

Alp familyAlpha C proteinRib proteinAlp1 (Epsilon)Alp2Alp3 (R28)Alp4C-alpha protein

Induction of opsonophagocytic antibodies that target the N-terminal domains of Alp family proteins, thereby inhibiting bacterial adherence to and invasion of host epithelial cells and promoting immune-mediated clearance (Pawlowski et al., 2022; Fischer et al., 2021).