Antiviral mechanism of carvacrol on HSV-2 infectivity through inhibition of RIP3-mediated programmed cell necrosis pathway and ubiquitin-proteasome system in BSC-1 cells

Li Wang,Yunlan Li,Xingan Wu,Rui Xu,Dan Wang

doi:10.1186/s12879-020-05556-9

Abstract

BackgroundCarvacrol, as the major components of aromatic plants used for treating human skin diseases including origanum, Satureja, thymus, and coridothymus species, presented a kind of antiviral activity. To explore the mechanisms of carvacrol against herpes simplex virus (HSV) in vitro.MethodThe BSC-1 cells model of HSV infection was established, and from the two aspects of viral replication level and cell death pathway, the antiviral effects of carvacrol on HSV infected cells were also evaluated by plaque assay under the three modes including prevention, treatment, and direct inactivation.ResultsIn the three ways, the half-maximal effective concentration (EC50) of 2% true carvacrol solution on HSV-2 infected cells were severally 0.43, 0.19 and 0.51 mmol/L, and the corresponding therapeutic index (TI) were 4.02, 9.11 and 3.39, respectively. It’s the opposite of the increased levels caused by HSV-2 infection, that both the expressions at the transcription genes and protein levels of virus own replication key factors (including ICP4, ICP27, VP16, gB, and UL30) and cytokines (including RIP3, TNF-α, and MLKL) of infected cells treated with carvacrol were dose-dependently inhibited. Besides, HSV-2 infection can cause the decrease of intracellular protein ubiquitination level, and carvacrol can reverse the ubiquitination decrease level caused by HSV-2 infection.ConclusionCarvacrol exhibits significant antiviral activity by inhibiting the HSV-2 proliferation process and HSV-2-induced TNF-α increasing levels, decreasing RIP3 and MLKL protein expressions through the intracellular RIP3-mediated programmed cell necrosis pathway. In addition, carvacrol also may exhibit anti-HSV-2 activity by reversing the ubiquitination decrease level caused by HSV-2 infection on the ubiquitin-proteasome system, which provides insights into the molecular mechanism.

Highlights

Carvacrol, as the major components of aromatic plants used for treating human skin diseases including origanum, Satureja, thymus, and coridothymus species, presented a kind of antiviral activity
To clarify whether BSC-1 cells can be infected with the herpes simplex virus (HSV) virus, the viral titer of both HSV-1 and Herpes simplex virus-2 (HSV-2) were compared on the different cell lines: African green monkey kidney cells (Vero) and BSC-1 cells
When carvacrol was applied on infected cells, it may exhibit anti-HSV-2 activity by inhibiting HSV-2-induced TNF-α increased levels, decreasing RIP3 protein activity and weakening MLKL protein expression

Summary

Introduction

As the major components of aromatic plants used for treating human skin diseases including origanum, Satureja, thymus, and coridothymus species, presented a kind of antiviral activity. Herpes simplex virus (HSV) is enveloped, linear and double-stranded DNA virus, which belongs to the family herpesviridae, genus alphaherpesvirinae. It is one of the most common pathogenic agents in humans and divided into two types: HSV-1 and HSV-2 [1]. The disadvantages of their narrow antiviral spectrum and high costs gradually aggravated people’s living burden [8,9,10], extremely in America [11] For these reasons, there is a need for the development of novel antiherpes drugs which are safe and preferably inexpensive with limiting the primary infection and supporting further treatment

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