Ib-AMP4 antimicrobial peptide as a treatment for skin and systematic infection of methicillin-resistant Staphylococcus aureus (MRSA)

Antimicrobial peptide compounds (AMPs) play important roles in the immune system. They also exhibit significant anti-tumor and antibacterial properties. Most AMPs are cationic and are able to bind bacterial cell membranes through electrostatic affinity. Ib-AMP4 is a plant-derived AMP that exerts rapid bactericidal functions. In the present study, the antibacterial efficiency of the produced recombinant Ib-AMP4 in elimination of Methicillin-resistant Staphylococcus aureus (MRSA) bacterial infection, was investigated under in vitro and in vivo situations. 

The synthesized Escherichia coli codon-optimized gene sequences of the Ib-AMP4 were expressed in E. coli BL21 (DE3) pLysS. The recombinant Ib-AMP4 was purified and refolding conditions were optimized. The antibacterial efficiency of the refolded peptide against MRSA was tested under in vivo and in vitro situations for treatment of skin and systematic infection of MRSA in a mouse model.

Antibacterial assays confirmed the antibacterial function of Ib-AMP4 against MRSA. SEM results proved the destructive effects of applying Ib-AMP4 on MRSA biomembrane. Time-kill curve and growth kinetic assay illustrated rapid antibacterial activity of the produced Ib-AMP4. Moreover, Ib-AMP4 showed significant infection treatment ability in a mouse model and all infected mice receiving Ib-AMP4 protein survived and there was no trace of bacteria in their blood samples.

The results confirmed the rapid antibacterial potential of the produced recombinant Ib-AMP4 to be used for efficient treatment of  MRSA infection.