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J Appl Microbiol. 2014 May;116(5):1149-63. doi: 10.1111/jam.12453. Epub 2014 Feb 12.

Antiviral efficacy and mechanisms of action of oregano essential oil and its primary component carvacrol against murine norovirus.

Author information

1
Department of Soil, Water and Environmental Science, The University of Arizona, Tucson, AZ, USA.

Abstract

AIMS:

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.

CONCLUSIONS:

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.

KEYWORDS:

human norovirus; mechanism of action; nonenveloped viruses; plant antimicrobials; sanitizer

PMID:
24779581
DOI:
10.1111/jam.12453
[Indexed for MEDLINE]
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