Research Article: Expression of recombinant HBD3 protein that reduces Mycobacterial infection capacity

Date Published: March 20, 2018

Publisher: Springer Berlin Heidelberg

Author(s): Feng Su, Xin Chen, Xin Liu, Guanghui Liu, Yong Zhang.


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.

Partial Text

Bovine tuberculosis is a chronic disease caused by Mycobacterium bovis (M. bovis) and is mainly characterized by the formation of granulomas in the lung and other organs (Muller et al. 2013). The disease causes great economic losses in cattle production every year. Killing of the suffering cattle as a common approach to reduce M. bovis prevalence results in great economic losses (Su et al. 2016). Our understanding on reducing these losses mainly focuses on tuberculosis prevention. This approach is divided into two major approaches. One of which is the vaccine method; however, the inefficient protection ability and potential virulence risk of antigen limits its application in cattle (Buddle et al. 2011). The other one is the prophylactic application of antibiotics in rational dosage. However, the ecological damage of probiotics in the animal body, and the pathogenic bacteria variation in the environment increased the cattle illness occurrence risk (Allen et al. 2010; Martinez 2008, 2009). Thus, a reasonable bio-agent is needed to reduce bovine Mycobacterial infection risk and environment contamination. Small potential human defensins that participated in the Mycobacterial immunity were recognized as suitable candidate agents that can reduce this risk (Driss et al. 2009; Rivas-Santiago et al. 2006). Among these defensins, human β-defensin 3 (HBD3) is an ideal potential one as previously reported.

Human β-defensins participate in the control of Mycobacteria multiplication in the latent infection stage (Rivas-Santiago et al. 2006). As a star molecule of human β-defensins, HBD3 participated in the in vivo killing of pathogenic microorganism that relies on its bioactivity (Auvynet and Rosenstein 2009). A recent study reported that HBD3-transgenic cattle reduces the susceptibility to M. bovis infection (Su et al. 2016). However, the expression of HBD3 in vitro and its accurate inhibition concentration are not yet determined. The results of the current study suggested that purified rHBD3 is obtained by recombinant DNA technology and prokaryotic expression system. Anti-bacterial tests revealed that rHBD3 protein maintains its basic bioactivity. Anti-Mycobacterial capacity study showed that rHBD3 protein reduces the M. bovis infectivity by killing the bacteria.




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