In vitro comparison of three common essential oils mosquito repellents as inhibitors of the Ross River virus.

Miora Ralambondrainy,Wildriss Viranaicken,Philippe Desprès,Petras Rimantas Venskutonis,Chaker El Kalamouni,Jimmy Sélambarom,Essia Belarbi,Pierre Roques,Renata Baranauskienė,Cheryl A Stoddart

doi:10.1371/journal.pone.0196757

Abstract

BackgroundThe essential oils of Cymbopogon citratus (CC), Pelargonium graveolens (PG) and Vetiveria zizanioides (VZ) are commonly used topically to prevent mosquito bites and thus the risk of infection by their vectored pathogens such as arboviruses. However, since mosquito bites are not fully prevented, the effect of these products on the level of viral infection remains unknown.ObjectivesTo evaluate in vitro the essentials oils from Reunion Island against one archetypal arbovirus, the Ross River virus (RRV), and investigate the viral cycle step that was impaired by these oils.MethodsThe essential oils were extracted by hydrodistillation and analyzed by a combination of GC-FID and GC×GC-TOF MS techniques. In vitro studies were performed on HEK293T cells to determine their cytotoxicity, their cytoprotective and virucidal capacities on RRV-T48 strain, and the level of their inhibitory effect on the viral replication and residual infectivity prior, during or following viral adsorption using the reporter virus RRV-renLuc.ResultsEach essential oil was characterized by an accurate quantification of their terpenoid content. PG yielded the least-toxic extract (CC50 > 1000 μg.mL-1). For the RRV-T48 strain, the monoterpene-rich CC and PG essential oils reduced the cytopathic effect but did not display virucidal activity. The time-of-addition assay using the gene reporter RRV-renLuc showed that the CC and PG essential oils significantly reduced viral replication and infectivity when applied prior, during and early after viral adsorption. Overall, no significant effect was observed for the low monoterpene-containing VZ essential oil.ConclusionThe inhibitory profiles of the three essential oils suggest the high value of the monoterpene-rich essential oils from CC and PG against RRV infection. Combined with their repellent activity, the antiviral activity of the essential oils of CC and PG may provide a new option to control arboviral infection.

Highlights

Management of arthropod-borne viruses related to neglected tropical diseases has become a global health public concern [1]
The inhibitory profiles of the three essential oils suggest the high value of the monoterpenerich essential oils from Cymbopogon citratus (CC) and Pelargonium graveolens (PG) against River virus (RRV) infection
The combination of gas chromatography-flame ionization detector (GC-FID) and GC-TOF MS allowed identifying 37, 67 and 53 components of the essential oils from CC, PG and Vetiveria zizanioides (VZ), respectively, and their major components are listed in Table 1

Summary

Introduction

Management of arthropod-borne viruses (arboviruses) related to neglected tropical diseases has become a global health public concern [1]. The discovery of novel prophylactic or therapeutic treatments against arboviruses remain a continuous goal aimed to counter emerging virus or new viral strains [2]. The RRV incubation period in humans was estimated to be from 7 to 9 days [4] and like the well-known Chikungunya virus that belongs to the same viral family, it typically causes fever, rash and polyarthralgia [5, 6]. The essential oils of Cymbopogon citratus (CC), Pelargonium graveolens (PG) and Vetiveria zizanioides (VZ) are commonly used topically to prevent mosquito bites and the risk of infection by their vectored pathogens such as arboviruses. Since mosquito bites are not fully prevented, the effect of these products on the level of viral infection remains unknown

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