Group B Streptococcus alpha-like protein (Alp)

The Group B Streptococcus (GBS) alpha-like protein (Alp) family consists of several large surface-anchored proteins, including Alpha C, Rib, Alp1, Alp2, Alp3, Alp4, and R28, which are key virulence factors in Streptococcus agalactiae (UniProt P13515, P26753). These proteins are characterized by a conserved N-terminal domain and a variable number of identical tandem repeats that facilitate bacterial interaction with host tissues (PMID: 26055475). Biologically, Alp family members function as adhesins, enabling the bacteria to attach to and invade human epithelial cells in the vaginal and respiratory tracts (PMID: 15342475). They also play a critical role in immune evasion by interfering with opsonophagocytosis and protecting the pathogen from host clearance. Clinically, GBS is a leading cause of neonatal sepsis, meningitis, and pneumonia, making these proteins high-priority targets for vaccine development (PMID: 30452636). Current therapeutic strategies focus on using recombinant N-terminal domains or fusion proteins to induce broad-spectrum immunity across multiple GBS serotypes. Ongoing clinical trials, such as those for the GBS6 and Minervax vaccines, aim to prevent maternal colonization and vertical transmission to infants by targeting these conserved antigens.

Other names

Alpha-like protein familyAlpha C proteinRib proteinAlp1Epsilon proteinAlp2Alp3Alp4R28 proteinSurface protein AlpStreptococcus agalactiae alpha-like protein

Induction of protective IgG antibodies that neutralize bacterial adherence and promote opsonophagocytic killing by host immune cells.