Cyclo(Phe-Pro) is a bacterial quorum-sensing molecule that has been found in V. cholerae.1 It enhances ToxR-dependent transcription of leuO, a DNA binding protein, and inhibits virulence factor production in V. cholerae. Cyclo(Phe-Pro) is an inhibitor of the interaction between retinoic acid-inducible gene I (RIG-I) and the ubiquitin ligase TRIM25.2 It increases the viral load in Huh7 cells infected with hepatitis C virus (HCV) when used at concentrations of 1, 2.5, and 5 mM. Cyclo(Phe-Pro) (50 mg/kg) reduces the expression of IFN-β induced by poly(I:C) and increases serum HCV titers in animal models of HCV infection.
1.Bina, X.R., Taylor, D.L., Vikram, A., et al.Vibrio cholerae ToxR downregulates virulence factor production in response to cyclo(Phe-Pro)mBio4(5)e00366-00313(2013) 2.Lee, W., Lee, S.-H., Kim, M., et al.Vibrio vulnificus quorum-sensing molecule cyclo(Phe-Pro) inhibits RIG-I-mediated antiviral innate immunityNat. Commun.9(1)1606(2018)