Alpha-like protein 1 (Alp1) (Alp1)

Alpha-like protein 1 (Alp1), also known as Epsilon, is a critical surface-anchored protein found in Streptococcus agalactiae (Group B Streptococcus or GBS), which is a leading cause of life-threatening neonatal infections (UniProt P0C0U1). It belongs to the Alpha-like protein (Alp) family, a group of virulence factors characterized by a conserved N-terminal domain and a variable number of tandem repeats that facilitate bacterial adhesion to host epithelial cells (PubMed 22434305). Alp1 plays a significant role in immune evasion by interfering with the host complement system, thereby enhancing bacterial survival within the bloodstream (PubMed 15103025). Due to its high prevalence in clinical isolates and its ability to elicit protective opsonophagocytic antibodies, Alp1 is a primary target for the development of maternal vaccines intended to provide passive immunity to newborns (PubMed 33166118). Current therapeutic strategies, such as the hexavalent GBS6 vaccine, utilize the N-terminal domains of Alp1 and other family members to provide broad-spectrum protection against diverse GBS serotypes (ClinicalTrials.gov NCT03765073).

Other names

Epsilon proteinAlp1Surface protein Alp1Alpha-like protein EpsilonGroup B Streptococcus Alpha-like protein 1

Induction of opsonophagocytic antibodies (IgG) that recognize the N-terminal domain of the protein, facilitating bacterial clearance by host immune cells.