Construction and bacteriostatic effect analyses of a recombinant thermostable Newcastle disease virus expressing cecropin AD

Abstract

Cecropin AD (CAD), a hybrid antimicrobial peptide composed of the first 11 residues of cecropin A and last 26 residues of cecropin D, is a promising antibiotic candidate. Therefore, an efficient and convenient method for producing CAD is necessary for commercial applications. The Newcastle disease virus (NDV) has been widely used as a platform for gene delivery and exogenous protein expression. In this study, we constructed a recombinant NDV that expresses CAD. To obtain high expression of the CAD peptide, tandem repeats of the cad gene were inserted into the genomes of the thermostable NDV strain TS09-C using reverse genetic technology. The thermostable recombinant NDV, namely rTS-CAD₃, showed thermostability and growth kinetics similar to those of their parental strain. A bacteriostatic test showed that rTS-CAD₃ inhibited Staphylococcus aureus (gram-positive bacteria) and Escherichia coli (gram-negative bacteria) in vitro. We further determined the bacteriostatic effects of rTS-CAD₃ expressed CAD against S. aureus in skin wound infections. The results showed that rTS-CAD₃ subcutaneously injection improved wound healing and reduced S. aureus decolonization. In summary, our results indicate that the rTS-CAD₃ expressing CAD peptide is a potent antimicrobial agent against S. aureus and E. coli and may be applied to accelerate wound healing in farm animals.