Alpha-like protein family N-terminal domain (Alp NTD)

The N-terminal domains of the alpha-like protein (Alp) family are critical surface-exposed virulence factors of Group B Streptococcus (GBS; Streptococcus agalactiae) (PubMed: 24511471). This protein family includes members such as Alpha C protein (ACP), Rib, Alp1, Alp2, Alp3, and Alp4, which share a common structural architecture consisting of a conserved N-terminal domain (NTD) followed by a variable number of tandem repeats (PubMed: 15103027). These NTDs are primarily involved in bacterial adhesion to host epithelial cells and the invasion of vaginal and neonatal barriers, which are essential steps in the progression of GBS infection (PubMed: 27161805). Because the NTDs are highly immunogenic and their structural folds are relatively conserved across different GBS clinical isolates, they serve as primary targets for recombinant subunit vaccine development (MinervaX, 2024). Therapeutic strategies, such as the GBS-NN and GBS-NN2 vaccines, utilize these recombinant domains to elicit high titers of opsonophagocytic antibodies in pregnant women. These antibodies are then transplacentally transferred to the fetus, providing passive immunity to protect neonates from life-threatening conditions like sepsis and meningitis (PubMed: 33159130).

Other names

Alp family N-terminal domainsGroup B Streptococcus surface protein N-terminal domainsGBS Alp NTDsAlpha-like protein N-terminal regions

Vaccine-mediated induction of protective opsonophagocytic antibodies (OPA) that neutralize bacterial adhesion to host cells and promote immune-mediated clearance by phagocytes (PubMed: 33159130).