The mechanism of action of pepR, a #viral-derived #peptide, against #Staphylococcus aureus #biofilms (J Antimicrob Chemother., abstract)

[Source: Journal of Antimicrobial Chemotherapy, full page: (LINK). Abstract, edited.]

The mechanism of action of pepR, a viral-derived peptide, against Staphylococcus aureus biofilms

Sandra N Pinto, Susana A Dias, Ana F Cruz, Dalila Mil-Homens, Fabio Fernandes, Javier Valle, David Andreu, Manuel Prieto, Miguel A R B Castanho, Ana Coutinho, Ana Salomé Veiga

Journal of Antimicrobial Chemotherapy, dkz223,

Published: 24 May 2019




To investigate the mechanism of action at the molecular level of pepR, a multifunctional peptide derived from the Dengue virus capsid protein, against Staphylococcus aureus biofilms.


Biofilm mass, metabolic activity and viability were quantified using conventional microbiology techniques, while fluorescence imaging methods, including a real-time calcein release assay, were employed to investigate the kinetics of pepR activity at different biofilm depths.


Using flow cytometry-based assays, we showed that pepR is able to prevent staphylococcal biofilm formation due to a fast killing of planktonic bacteria, which in turn resulted from a peptide-induced increase in the permeability of the bacterial membranes. The activity of pepR against pre-formed biofilms was evaluated through the application of a quantitative live/dead confocal laser scanning microscopy (CLSM) assay. The results show that the bactericidal activity of pepR on pre-formed biofilms is dose and depth dependent. A CLSM-based assay of calcein release from biofilm-embedded bacteria was further developed to indirectly assess the diffusion and membrane permeabilization properties of pepR throughout the biofilm. A slower diffusion and delayed activity of the peptide at deeper layers of the biofilm were quantified.


Overall, our results show that the activity of pepR on pre-formed biofilms is controlled by its diffusion along the biofilm layers, an effect that can be counteracted by an additional administration of peptide. Our study sheds new light on the antibiofilm mechanism of action of antimicrobial peptides, particularly the importance of their diffusion properties through the biofilm matrix on their activity.


Keywords: Antimicrobial peptides; Biofilm; Staphylococcus aureus.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum ( in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.