In Vitro Anti Porcine Reproductive And Respiratory Syndrome Virus Effects Of 14 Traditional Chinese Medicines

Porcine reproductive and respiratory syndrome（PRRS）is an infectious disease caused by porcine reproductive and respiratory syndrome virus（PRRSV）,which is characterized by reproductive dysfunction and respiratory symptoms.After PRRSV infection,the overexpression of proinflammatory factors,will cause tissue and organ damage in the body.At present,there is no specific medicine,and the main means of prevention and control are vaccine immunization and biosecurity prevention and control.In recent years,studies have found that TCMs have strong antiviral activity,which not only can directly inhibit or kill viruses,but also enhance body immunity.In order to investigate the in vitro anti porcine reproductive and respiratory syndrome virus activity of 14 herbs including Houttuynia cordata,caprifolia morifolium,and variola powder,based on the establishment of a Marc-145 cell model and determination of its maximum safe concentration on Marc-145 cells,MTT assay was applied to explore its inhibitory effect on PRRSV by three modes of action:blocking,inhibiting,and killing.The relative expression of cytokines IL-6,IL-8 and TNF-αafter drug and virus effects were further measured by fluorescence quantitative PCR to explore the mechanism of anti PRRSV in TCM.The drug toxicity test showed that the safety concentration of traditional Chinese medicine was between 0.78 mg/m L and 25 mg/m L,in which Scrophularia ningpoensis was the highest,25 mg/m L,Arnebia euchroma and Polygonum cuspidatum was the lowest,0.78 mg/m L.The TCID₅₀of PRRSV-JXA1 strain was 10^-6.8/0.1m L.In vitro antiviral assays showed that Polygonum cuspidatum,Glycyrrhizae radix,Houttuynia cordata,radicicol,and Polygonum purpureus were the most effective in blocking PRRSV,while direct killing of PRRSV was obtained from Polygonum cuspidatum,Polygonum cuspidatum,Houttuynia cordata,Scrophularia radix,and Polygonum cuspidatum.Of the combined three modes of action,Houttuynia cordata and Polygonum cuspidatum showed greater inhibition of porcine reproductive and respiratory syndrome virus.qPCR method was used to explore the relative expression of IL-6,IL-8 and TNF-αin Houttuynia cordata Thunb and Polygonum cuspidatum.The results showed that compared with the cell control group,the levels of IL-6,IL-8 and TNF-αin the virus control group were significantly increased,and the expression levels of IL-6,IL-8 and TNF-αdecreased with the increase of drug concentration under the three action modes,with different changes.However,compared with the virus control group,Houttuynia cordata Thunb and Polygonum cuspidatum could significantly（p<0.05）or extremely significantly（p<0.01）reduce the expression of IL-6,IL-8 and TNF-α.The results showed that Houttuynia cordata Thunb and Polygonum cuspidatum could reduce the production of pro-inflammatory cytokines IL-6,IL-8 and TNF-αin Marc-145 cells infected with PRRSV.