Expression of recombinant HBD3 protein that reduces Mycobacterial infection capacity

Bovine tuberculosis is a disease caused by Mycobacterium bovis (M. bovis) that leads to great economic losses in cattle production. The discovery of a reasonable bioagent to reduce M. bovis infection risk and environment contamination becomes significant and urgent. Previous study reported that human β-defensin-3 (HBD3) participated in Mycobacterial immunity and was recognized as a suitable candidate reagent. However, its minimal inhibitory concentration to M. bovis is not yet reported. In this study, we first purified HBD3 protein by recombinant-DNA technology and prokaryotic expression system. Subsequently, anti-bacterial tests were used to evaluate the basic bioactivity of the protein. Results revealed that recombinant HBD3 (rHBD3) protein inhibits Staphylococcus multiplication but not the host Escherichia coli. The growth curve of M. bovis showed that rHBD3 protein controls the proliferation of M. bovis in 20 μg/ml concentration. In addition, rHBD3 protein-incubated M. bovis exhibited reduced infectivity to alveolar epithelial cells and macrophages. In conclusion, the expression of rHBD3 protein is a potential ideal bio-regent for reducing M. bovis infection.