In vitro screening antiviral activity of Thai medicinal plants against porcine reproductive and respiratory syndrome virus

Chaiwat Arjin,Kidsadagon Pringproa,Surat Hongsibsong,Korawan Sringarm,Warintorn Ruksiriwanich,Mintra Seel-Audom,Supamit Mekchay

doi:10.1186/s12917-020-02320-8

Abstract

BackgroundPorcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) results in economic losses in the swine industry globally. Several studies have investigated the use of plant extracts in the prevention and control of PRRS outbreaks. Thai medicinal plants may be useful for treating PRRSV infection in pigs. Therefore, we investigated the in vitro anti-PRRSV and antioxidant properties of seven Thai medicinal plants: Caesalpinia sappan Linn., Garcinia mangostana Linn., Houttuynia cordata, Perilla frutescens, Clinacanthus nutans, Phyllanthus emblica, and Tiliacora triandra.ResultsUsing antiviral screening, we observed that T. triandra extract strongly inhibited PRRSV infectivity in MARC-145 cells [virus titer 3.5 median tissue culture infective dose (TCID50)/ml (log10)] at 24 h post-infection, whereas C. sappan extract strongly inhibited PRRSV replication [virus titer 2.5 TCID50/ml (log10)] at 72 h post-infection. C. sappan extract had the highest total phenolic content [220.52 mM gallic acid equivalent/g] and lowest half-maximal inhibitory concentration [1.17 mg/ml in 2,2-diphenyl-1-picrylhydrazyl and 2.58 mg/ml in 2,2-azino-bis (3-ethylbenzothiazo-line-6-sulfonic acid) diammonium salt].ConclusionT. triandra extract could inhibit PRRSV infectivity, whereas C. sappan extract was the most effective in inhibiting PRRSV replication in MARC-145 cells. This study elucidates the antiviral activities of Thai medicinal plant extracts in vivo. The results promise that Thai medicinal plant extracts, particularly T. triandra and C. sappan extracts, can be developed into pharmaceutical drugs for the prevention of PRRS in pigs.

Highlights

Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) results in economic losses in the swine industry globally
Cytotoxic activities of plant extracts Prior to determining antiviral activity, we evaluated the cytotoxicity of the seven Thai medicinal plant extracts on the viability of MARC-145 cells, and viability is expressed as 50% cytotoxic concentration (CC50)
The results showed that the CC50 of the seven plant extracts ranged from 78 to 2500 μg/ml, and the effect of Thai medicinal plant extract concentration on the tested cells increased in a dose-dependent manner (Fig. 1)

Summary

Introduction

Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) results in economic losses in the swine industry globally. Porcine reproductive and respiratory syndrome virus (PRRSV) is endemic in most pig-producing countries, and it results in enormous economic losses to the swine industry globally [1]. PRRSV infection causes a disease that is characterized by reproductive failure in sows and respiratory infections in growing pigs [3], and this disease predisposes pigs to infection by bacteria and other viral pathogens [4, 5] This disease is known as porcine reproductive and respiratory syndrome (PRRS) and has become endemic in many countries throughout the world following an epidemic phase [6, 7]. It has become a major infectious disease that causes high mortality in swine and production losses in the swine industry in this country

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