RNAIII inhibiting peptide (RIP) inhibits agr-regulated toxin production.

Staphylococcal enterotoxins (SEs) are emetic toxins that cause food poisoning. SEs also function as powerful pyrogenic toxin superantigens that stimulate non-specific T-cell proliferation. Together with the hemolysins, SEs have been largely implicated as virulence factors in multiple infection models. Recent biochemical and genetic analyses have demonstrated that production of some of these toxins is partially regulated by quorum sensing mechanisms where proteins and peptides activate the accessory gene regulator (agr). Because toxin production is central to bacterial pathogenesis, therapeutic strategies alternative to antibiotics, and based on rational interference of the quorum sensing systems involved, are currently being developed. This approach would lead to repression of toxin production and, thus, to disease prevention. Here we provide evidence to conclude that synthetic analogs of the RNAIII inhibiting peptide (RIP) and antibodies to its target molecule TRAP function in vitro as efficient suppressors of agr-regulated exotoxin production by Staphylococcus aureus.