Antiviral efficacy and mechanisms of action of oregano essential oil and its primary component carvacrol against murine norovirus
Article first published online: 12 FEB 2014
© 2014 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 116, Issue 5, pages 1149–1163, May 2014
How to Cite
Gilling, D.H., Kitajima, M., Torrey, J.R. and Bright, K.R. (2014), Antiviral efficacy and mechanisms of action of oregano essential oil and its primary component carvacrol against murine norovirus. Journal of Applied Microbiology, 116: 1149–1163. doi: 10.1111/jam.12453
- Issue published online: 11 APR 2014
- Article first published online: 12 FEB 2014
- Manuscript Revised: 13 JAN 2014
- Manuscript Accepted: 13 JAN 2014
- Manuscript Received: 5 NOV 2013
- Organic Agriculture Research and Extension Initiative. Grant Number: 2010-51300-21760
- plant antimicrobials;
- human norovirus;
- mechanism of action;
- nonenveloped viruses
To investigate the antiviral efficacy of oregano oil and its primary active component, carvacrol, against the nonenveloped murine norovirus (MNV), a human norovirus surrogate.
Methods and Results
Along with an observed loss in cell culture infectivity, the antiviral mechanisms of action were determined in side-by-side experiments including a cell-binding assay, an RNase I protection assay and transmission electron microscopy (TEM). Both antimicrobials produced statistically significant reductions (P ≤ 0·05) in virus infectivity within 15 min of exposure (c. 1·0-log10). Despite this, the MNV infectivity remained stable with increasing time exposure to oregano oil (1·07-log10 after 24 h), while carvacrol was far more effective, producing up to 3·87-log10 reductions within 1 h. Based on the RNase I protection assay, both antimicrobials appeared to act directly upon the virus capsid and subsequently the RNA. Under TEM, the capsids enlarged from ≤35 nm in diameter to up to 75 nm following treatment with oregano oil and up to 800 nm with carvacrol; with greater expansion, capsid disintegration could be observed. Virus adsorption to host cells did not appear to be affected by either antimicrobial.
Our results demonstrate that carvacrol is effective in inactivating MNV within 1 h of exposure by acting directly on the viral capsid and subsequently the RNA.
Significance and Impact of the Study
This study provides novel findings on the antiviral properties of oregano oil and carvacrol against MNV and demonstrates the potential of carvacrol as a natural food and surface (fomite) sanitizer to control human norovirus.