Antiviral activity of recombinant mouse β-defensin 3 against influenza A virus in vitro and in vivo.

Jiang, Yan; Yang, De; Li, Wanyi; Wang, Baoning; Jiang, Zhonghua; Li, Mingyuan

BACKGROUND Influenza causes significant morbidity and mortality. Mammalian β-defensins are small peptides of about 4.5-6 kDa in mass and are effectors of the innate immune response with potent antimicrobial activity. In this paper, we focused on the anti-influenza A activity of the recombinant mouse β-defensin 3 (rMBD-3) in vivo and in vitro. METHODS The rMBD-3 peptide was added to Madin-Darby canine kidney (MDCK) cells at different stages of influenza A virus (IAV) A/PR/8/34 (H1N1) infection and its virus inhibitory properties were determined. Mice were infected with IAV and treated with rMBD-3 peptide from 12 h post-infection. The effect of rMBD-3 peptide was determined by pulmonary viral load, pathology and mortality. In addition, the expression of interleukin (IL)-12, interferon (IFN)-γ and tumour necrosis factor (TNF)-α genes in mice with or without rMBD-3 treatment was determined by semi-quantitative reverse transcriptase PCR. RESULTS rMBD-3 was shown to protect MDCK cells against IAV infection and had a major role in inhibition of adsorption and uptake by cells infected with IAV. Following the addition of 100 μg/ml rMBD-3 to MDCK cells medium, approximately 80% of cells were protected from infection in vitro. rMBD-3 given by tail vein injection (10 mg/kg/day) was the most effective method to improve the survival rate of the mice. Treatment with rMBD-3 was found to up-regulate IFN-γ and IL-12 gene expression, but reduced expression of the TNF-α gene. CONCLUSIONS These results demonstrate that rMBD-3 possesses anti-influenza virus activity both in vivo and in vitro that might be of therapeutic use.