Effect Of Matrine And Glycyrrhizic Acid Compounds On Porcine Reproductive And Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome is widespread（PRRS） worldwide,seriously affecting the development of the pig industry.Currently,the protection of PRRS mainly depends on vaccine immunization,However,due to the mutation of porcine reproductive and respiratory syndrome virus（PRRSV）and the presence of antibody dependent enhancement（ADE）,the results are not satisfactory.Chinese herbal medicine having been used for antivirus has a long history in China.Glycyrrhizic acid and matrine with antiviral effect were screened out from Chinese herbal medicine.Compounds of matrine and glycyrrhizin were tested in vitro and in vivo to explore the effect of anti-PRRSV.This study consists of three parts.1 Effect of matrine and glycyrrhizin compound on PRRSV in vitro.Seven compounds of glycyrrhizic acid and matrine were prepared by different mass ratio: 1:1,1:2,1:3,1:4,2:1,3:1,4:1.The antiviral test in vitro was carried out by using Marc-145 cells.The results showed that different compounds had therapeutic and direct killing effects on PRRSV,and the effect is better than monomer.Compound of matrine and glycyrrhizic acid at 0.25 mg/mL in mass ratio of 1:4,showing the best efficacy in the treatment and direct killing test,the inhibition rate was 76.95% and 83.25%,and the treatment index was 12.696.It was found that the earlier the drug intervened in virus-infected cells,the better the effect.When the cells was infected by virus for more than 24 hours,the drugs has no inhibitory effect on virus replication（P>0.05）.The optimal compound can reduce the TCID₅₀ of the virus and has a positive correlation with the concentration of the drug in the safe concentration range.2 Study on the anti PRRSV of matrine and glycyrrhizin compound in pigs.The test is divided into the control group and the control cohabitation infection group,the medication group and the medication cohabitation infection group.The results showed that the morbidity of all groups was 100%,and there was no significant difference in mortality among all groups（P>0.05）.In body temperature and antibody test,there was no significant difference between the control group and the medication treatment group（P>0.05）,and there was no significant difference between the two cohabiting groups（P>0.05）.From the clinical symptoms,the medication treatment group showed acute death after drug use,and the mortality rate reached 75% on the eighth day after drug treatment.At this time,there was no death in the control group.The results showed that the prescription accelerated the death of the test pigs,and showed no anti PRRSV effect in vivo.3 Effect of matrine and glycyrrhizic acid compound on PRRSV live vaccine immune in pigs.There were 4 groups: the Immunotherapy group and the immune control group,the non Immunotherapy group and the non immune control group.The results showed that the incidence of PRRSV infection was 0% and 20% by clinical symptoms respectively in the immune control group and the immune medication group after challenge.There was no significant difference between the two groups（P>0.05）.The morbidity of non-immune control group and treatment non-immune group were 100%,and the mortality is 60% and 80% respectively There was no significant difference between the two groups（P>0.05）.The morbidity and mortality of pigs not inoculated with live vaccine were significantly higher than those of the immunization group（P<0.05）.During the experiment,there was no significant difference in body weight,body temperature and PRRSV N protein antibody between the treatment group and the control group（P>0.05）.There was no significant difference in cytokine levels between the non-immunized groups during immunization.The levels of IL-6,IL-8,IFN-α,and TNF-α inflammatory factors in the Immunotherapy group were significantly higher than those in the immunized control group at 14 days of immunization（P<0.05）,the cytokine levels in the Non-immune medication group were significantly higher than the non-immunized control group at multiple time points（P<0.05）;the non-immune group cytokine levels were higher than the immune at multiple time points.The results showed that matrine and glycyrrhizic acid compound had no synergistic effect with PRRSV live vaccine in vivo,can enhance the inflammatory reaction of pigs infected with PRRSV virulent strain,and cause the body to produce excessive inflammatory factors,causing damage to the body,and the therapeutic effect was unsatisfactory.