Screening Of Anti-PRRSV Of Chinese Herbal Polysaccharide And Its Compound In Vitro

Porcine reproductive and respiratory syndrome(PRRS) caused by Porcine reproductive and respiratory syndrome virus (PRRSV) is characterized by the symptoms, fever, anorexia and miscarriage, premature birth, stillbirth, weak and mummified fetus in pregnant sows, and a highly contagious respiratory disorders disease in all ages pigs (especially piggy). In 1992, it was named porcine reproductive and respiratory syndrome by the International Veterinary Bureau. To date, no effective treatment drug was found. So, the disease has spreaded all over North America and Europe, and spreaded across the globe.Nowadays, viral disease has become one of the greatest threats to the health of humanbeings and animals. Vaccines and antiviral drugs have become the main prevention and treatment ways. In recent years, antiviral medicine prepartion of TCVM has been paid more and more attention. The most important form and essence in application of traditional Chinese medicine are prescription with compatible form. According to the preliminary screening results of single herb polysaccharides, the experiment choose six polysaccharides which showed well anti-PRRSV activity in vitro to form eight polysaccharide compounds based on the principle of compatibility. The antiviral effects of these prescriptions in vitro were observed by MTT assay. The purpose is to screen anti-PRRS herbal polysaccharide compound, and to provide a reference for the prevention and treatment of PRRS in clinic.In this experiment, polysaccharides in eight herbal medicines, including Epimedium, Radix, Polygahatous, lycium barbarum, Angelica, Garlic, Astragalus and Codonopsis were extracted by water-decoction and ethanol-precipitation methods. The contents of eight polysaccharides were measured by Phenol-sulfuric acid method. The results showed that the extractive rates (g.kg-1) of Epimedium polysaccharide (EPS), Isatis root polysaccharide (IRPS), Pohygonatum sibiricmu polysaccharide(PSP), lycium barbarum polysaccharide (IBP), Codonopsis pilosula polysaccharide(CPP), Angelica sinensis polysaccharide(ASP), Garlic polysaccharide(GP), Astragalus polysaccharide(APS) were 55.2,61.9,35.6,48.5, 53.6,49.3,62.7 and 39.1 respectively. The net contents of polysaccharides were 16.8%, 74.0%,46.1%,36.5%,47.9%,22.4%,93.4% and 66.0% respectively.To evaluate the antiviral activity of these polysaccharides, EPS, IRPS, PSP, LBP, CPP, ASP, GP and APS were added into Marc-145 monolayer with three sample-adding modes of pre-, post-and simultaneously-adding with PRRSV respectively. The pathological changes of the cells and the values of OD570 measured by MTT assay were determined to evaluate the antiviral infecting effects of the eight polysaccharides in vitro. The results showed that EPS, IRPS, PSP, LBP, CPP and APS proformed better anti-PRRSV effect than ASP and GP.Based on the antiviral effects of single polysaccharide, six kinds of polysaccharides with better antiviral effect were used to form eight polysaccharide compounds. The anti-PRRSV effects of the eight principles were investigated with three sample-adding modes of pre-, post-and simultaneously-adding with PRRSV respectively. The results showed that the prescriptions â‘¡ and â‘¢ respectively performed better anti-PRRSV effect.