Virginia Research Day 2021

Faculty Research Biomedical

03 Peptide Nucleic Acids for the Prevention/Treatment of Persistent Infections Caused by Staphylococcus aureus Biofilms

Nihan Akguc Col 1* ; Jayasimha Rao 2 ; Govindarajan Rajagopalan 3 ; Nammalwar Sriranganathan 1 Corresponding author: nihana@vt.edu

1 Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech 2 Department of Medicine, Division of Infectious Diseases, Carilion Clinic, Virginia Tech Carilion School of Medicine, 3 Department of Internal Medicine, Yale School of Medicine, Yale University

Staphylococcus aureus readily forms biofilms, which is one of the common mechanisms of antibiotic resistance and plays a crucial role in progression of infections in humans and animals. It is a challenge to treat of such biofilm infections, often leads to antibiotic resistance, thereby causing persistent infection of wounds, heart valves and other living tissue as well as various indwelling devices such as catheters, cardiac implants and prosthetic joints, causing enormous economic and clinical burden. Hence, novel approaches to prevent/treat biofilm formation by this pathogen are urgently needed. In this context, inhibition of bacterial gene expression using peptide nucleic acids (PNAs) is an effective mean to either kill bacteria or to prevent biofilm

targeting sarA gene was able to significantly interfere with S. aureus biofilm formation. Our results showed that anti- sarA P-PNA at 50 μM can prevent the biofilm formation on the surface of low binding microtiter plate. However, CPP and scrambled PNAs had no effect on both inhibition bacterial growth as well as biofilm formation. Thus, our findings have the potential as an alternative strategy to prevent/treat biofilm formation by S. aureus and hence has clinical utility.

formation. Therefore, we envisioned that a potential strategy for the prevention of S. aureus biofilm infections would be to use PNAs to down-regulate or abolish the expression of specific genes associated with biofilm formation. Antisense PNAs linked with cell penetrating peptides (CPP) designated as P-PNAs targeting S. aureus -essential genes as well as genes important for biofilm formation were designed, and commercially synthesized along with scrambled P-PNAs (control) with CPP. The biofilm inhibitory activities of the synthesized P-PNAs targeting the three essential genes ( fmhB, yycF & yycG ), and four genes relevant to biofilm formation ( icaA, sarA, saeS, rot ) were tested against S. aureus P231 strain by a standard microtiter biofilm assay. Only P-PNA

This study was funded in part by the VCOM One Health Seed Grant.

B

A

Figure 1. (A) Image of S. aureus P231 strain biofilm treatment with P-PNAs in microtiter plate after removing the liquid culture of the wells at 48 h. (B) Percentage biofilm inhibition in S. aureus by peptide nucleic acids (PNAs). Crystal violet staining was performed to assess biofilm formation on 96-well low binding microtiter plate at 48 h.

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