Staphylococcus aureus Alpha-hemolysin (Hla)

Staphylococcus aureus Alpha-hemolysin (Hla), commonly referred to as Alpha-toxin, is a major virulence factor and a potent pore-forming exotoxin secreted by most clinical isolates of S. aureus (UniProt P09616). The toxin is secreted as a water-soluble monomer that binds to the host cell surface receptor ADAM10, where it assembles into a heptameric prepore before inserting a beta-barrel into the plasma membrane (PubMed: 25535925). This pore formation leads to the leakage of intracellular contents, osmotic lysis, and the induction of programmed cell death in various host cells, including epithelial cells, endothelial cells, and leukocytes. Hla also triggers pro-inflammatory signaling and disrupts tissue barriers, which is central to the pathogenesis of severe conditions such as ventilator-associated pneumonia and sepsis (PubMed: 23935147). In the pharmaceutical industry, Hla is a high-priority target for passive immunization strategies, with several monoclonal antibodies like suvratoxumab and tosatoxumab in clinical development (ClinicalTrials.gov: NCT02296320, NCT03816956). These therapeutic agents aim to neutralize the toxin's activity, thereby limiting tissue damage and improving the efficacy of standard antibiotic treatments.

Other names

Alpha-toxinAlpha-hemolysinHlyATStaphylococcal alpha-toxin

Neutralization of the toxin by monoclonal antibodies prevents its binding to the host receptor ADAM10 and subsequent oligomerization into a heptameric pore, thereby protecting host cells from lysis and reducing inflammatory damage (PubMed: 25535925).