Conserved Staphylococcal Antigen 1 (Csa1) (Csa1)

Conserved Staphylococcal Antigen 1 (Csa1) is a surface-exposed lipoprotein that is highly conserved across diverse clinical isolates of Staphylococcus aureus (PubMed: 20660679). Identified through reverse vaccinology, Csa1 contains Sel1-like repeats, which are motifs typically associated with protein-protein interactions and may contribute to bacterial virulence or cell wall maintenance (UniProt: Q2FYB0). It serves as a key component in multi-antigen vaccine candidates, such as Pfizer's PF-06290510 (SA4Ag), which also includes Clumping factor A (ClfA) and capsular polysaccharides (ClinicalTrials.gov: NCT02388321). The primary therapeutic goal of targeting Csa1 is to induce opsonophagocytic antibodies that facilitate the clearance of S. aureus by host immune cells, particularly neutrophils. While Csa1 showed promise in preclinical models, clinical trials for vaccines containing this antigen have encountered difficulties in meeting primary efficacy endpoints for preventing invasive S. aureus infections in surgical patients (PubMed: 31034536). The protein is anchored to the cell membrane via a lipid moiety, making it an accessible target for the host's humoral immune response. Its high degree of conservation makes it an attractive target for providing broad-spectrum protection against various S. aureus strains, including methicillin-resistant S. aureus (MRSA). Despite the challenges in clinical translation, Csa1 remains a significant focus in the study of staphylococcal immunology and vaccine design.

Other names

Lipoprotein Csa1SA0688Sel1 repeat-containing proteinConserved staphylococcal antigen 1

Induction of opsonophagocytic antibodies that facilitate the clearance of Staphylococcus aureus by immune cells.