Effect Of Chinese Traditional Medicine Polysaccharide As Immunopotentiators On PRRS Attenuated Vaccine

Porcine Reproductive and Respiratory Syndrome is a highly contagious and severe viral disease caused by porcine reproductive and respiratory syndrome virus,which mainly causes symptoms of sow reproductive failure and respiratory symptoms of piglets.It still causes huge loss in global pig industry every year.The main means of prevention and control of porcine reproductive and respiratory syndrome is to immunize with traditional vaccines,but the effect is not satisfactory,and it is necessary to find a way to improve the vaccine effect.Traditional Chinese medicine contains many effective and active ingredients.It has been found that the polysaccharides in the extract have anti-virus,anti-aging,immune-enhancing and other biological activities,and have the potential to be developed into immunopotentiators.In this experiment,two kinds of traditional Chinese medicines,Epimedium and Gynostemma pentaphyllum,were used for polysaccharide extraction and determination.The antiviral and immunopotentiating effects of Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide were investigated by in vitro and in vivo experiments,and the possibility of its use as a PRRSV attenuated vaccine immunopotentiator was evaluated.The main research contents and summary are as follows.The polysaccharides of Epimedium and Gynostemma pentaphyllum were extracted by water extraction and alcohol precipitation method to obtain polysaccharides from Epimedium and Gynostemma pentaphyllum.The content of polysaccharides was determined by phenol-sulfuric acid method.The results showed that the extraction rate of Epimedium polysaccharides was 8.47%,and the net content was 63.08%,the extraction rate of Gynostemma pentaphyllum polysaccharide was 10.34%,and the net content was 55.67%.The antiviral effect of Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide on PRRSV was determined by CPE observation method.The results showed that Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide could block the infection of PRRSV on Marc-145 cells in a safe concentration range.With the increase of dilution,the anti-infection effect was reduced.When the concentration of Epimedium polysaccharide was 32.15 μg/m L,The anti-infection effect was best.When the concentration of Gynostemma pentaphyllum polysaccharide was 62.5 μg/m L,the anti-infection effect was the best.The concentration of Epimedium polysaccharide had a certain inhibited effect on PRRSV proliferation at the concentration of 31.25 μg/m L,but the effect is not strong,and there is no inhibited effect on PRRSV proliferation at concentrations of 15.625 μg/m L,7.8125 μg/m L,3.9063 μg/m L;The concentration of Gynostemma pentaphyllum polysaccharides at 62.5 μg/m L,31.25 μg/m L,15.625 μg/m L,7.8125 μg/m L,there is no inhibited effect on PRRSV proliferation at the concentration.The mice were administered with different concentrations of Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide to observe the effects on the organs of mice and the determination of spleen index.The results showed that Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharides were continuously administered for 7 days at 150 mg/kg and 50 mg/kg,and had no toxic effects on the main organs of mice.When Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide were.at doses of 150 mg/kg and 50 mg/kg,the spleen index of mice was significantly increased,and the effect of 150 mg/kg was better than that of 50 mg/kg.The clinical trials of different doses of Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide as immunopotentiators for PRRSV attenuated vaccine were conducted to investigate the effects of serum antibody level and dispersion,IFN-γ,IL-12 and serum neutralizing antibody titers.The results showed that Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide could significantly increase the serum antibody level of PRRSV at the dose of 150 mg/kg for 28 days(P<0.05);Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharides at the dose of 150 mg/kg and 50mg/kg can reduce the dispersion of serum antibody levels of PRRSV;the concentration of epimedium polysaccharide can significantly increase serum IFN-γ level at the dose of 150 mg/kg on the 35 th day after immunization(P<0.05);When Gynostemma pentaphyllum polysaccharides were at the dose of 150 mg/kg,serum IL-12 levels were significantly increased on the 35 th day after immunization(P<0.05).Epimedium polysaccharide could significantly increase serum neutralization antibody titer at the dose of 150 mg/kg on the 28 th day after immunization.;epimedium polysaccharide,Gynostemma pentaphyllum polysaccharide at dose of 150 mg/kg and 50 mg/kg,can significantly increase serum neutralizing antibody titer on the 35 th day after immunization(P<0.05).This study showed that Epimedium polysaccharide and Gynostemma pentaphyllum polysaccharide have a good immune enhancement effect on PRRSV attenuated vaccine,which provides theoretical basis and technical support for exploring new Chinese medicine immune enhancer.