LL37-rIb-AMP4 Hybrid Peptide as a Therapy for Systematic Infections of Acinetobacter baumannii, Pseudomonas aeruginosa, Vancomycin-resistant Enterococcus (VRE), and Methicillin-resistant Staphylococcus aureus (MRSA) cells in a mouse model.

Abstract

Background: Antimicrobial peptides (AMPs) are beneficial compounds that could be used as a new and effective method to suppress microbes. Both Ib-AMP4 and LL37 are antimicrobial peptides with a wide range of antimicrobial activities. This research aimed to evaluate the antibacterial potential of LL37-rIb-AMP4 hybrid protein as an antimicrobial agent against pathogenic bacteria. Therefore, its antibacterial effects against Acinetobacter baumannii, Pseudomonas aeruginosa, vancomycin-resistant Enterococcus (VRE), and methicillinresistant Staphylococcus aureus (MRSA) were investigated in vivo and in vitro.Materials & Methods: In this study, antimicrobial peptides rIb-AMP4, LL37, and LL37-rIb-AMP4 were expressed, purified, and refolded, and their synergistic and antibacterial effects in combination with each other (LL37+rIb-AMP4) and as fusion proteins (LL37-rIb-AMP4) were tested against A. baumannii, P. aeruginosa, VRE, and MRSA cells in vitro (MIC, time kill, and SEM) and against P. aeruginosa and VRE cells in vivo. Findings: LL37-rIb-AMP4 Protein with molecular weight= 28 KD was correctly produced and purified. Despite the lack of synergistic effects between LL37 and rIb-AMP4 peptides in vitro, the stability test results showed higher stability for LL37-rIb-AMP4 hybrid protein.The findings of in vivo tests confirmed that all infected mice were improved with LL37-rIb-AMP4 and no signs of bacteria were observed in their blood and spleen samples. Also, these results confirmed the stability and higher activity of LL37-rIb-AMP4 than the single form of these proteins. Conclusion:Considering the antimicrobial potential of the produced proteins, it seems that the recombinant LL37-rIb-AMP4 protein could be considered and used as a stable and active antimicrobial drug in future studies.