| Porcine reproductive and respiratory syndrome(PRRS)is a highly contagious disease caused by porcine reproductive and respiratory syndrome virus(PRRSV),which is characterized by sow reproductive disturbance and respiratory symptoms of commercial pigs.In recent years,PRRS has widely speared in China and seriously threatened the development of the pig industry.At present,the disease is mainly prevented by vaccination,due to the high-frequency mutation of PRRSV strain,the efficiency of immunization is not satisfied.Traditional Chinese medicine has direct or indirect antiviral effects on prevention and therapy against viral diseases.Yedahuang powder was composed of Yebazi,Turhubarb,clam grass,and ramie root.It is a kind of traditional Chinese medicine for clearing heat and detoxifying toxins.It has the functions of strengthening the body,eliminating pathogens,clearing heat and detoxifying toxins,cooling blood,stopping bleeding,and benefiting the fetus.This study evaluated the effect of Yedahuang powder on PRRS prevention in large scale pig farms and provided the reference for further commercial development and clinical application.1 PRRS Serological Epidemiology Survey on Large-scale Pig Farms in Jiangsu ProvincePRRSV antibody was detected with ELISA for 2062 serum samples from 27 pig farms in 7 regions of Jiangsu Province.The results showed that the total positive rate of PRRSV in 27 pig farms without immunization was 68.82%.The positive rate of antibodies in Suqian and Nantong was 72.04%and 71.09%respectively,and the lowest value was 58.82%from Lianyungang.According to the annual statistics,the positive rate of antibody had decreased from 76.41%to 57.72%from 2016 to 2018.The positive rate of antibody in sows and 18-25 weeks growing and fattening pigs were 92.86%and 98.09%respectively.2 Toxicity test of extract from Yedahuang powderHPLC was conducted to confirm the composition of Yedahuang powder extract.The acute toxicity and subchronic toxicity of this drug were determined with mice challenging experiments by detecting organ index,blood routine,serum biochemical and immunological index,and histopathological observation.Results showed that flavonoids and anthraquinone compounds are the main components.LD50 is too high to be determined in the acute toxicity test,and MTD was more than 120 g/kg.d.Compared to the blank control group,the behavior of mice in each treatment group was normal,and there was no significant difference between blood routine and blood biochemical indicators such as red blood cell count,white blood cell count,aspartate aminotransferase,alanine aminotransferase,creatinine and urea There were no significant pathological changes in the heart,liver,spleen,kidney,and other tissues.3 Inhibitory effect of Yedahuang powder extract against PRRSV in vitroTreat Marc-145 cells with different concentration of Yedahuang powder extract(125.00,62.50,31.25,15.62,7.81,3.90,1.95,0.97 and 0.48 mg/mL).the cell survival rate was calculated by the MTT method,and the toxic effect of the extract on the cells was determined.Three doses of 15.62 mg/mL(high dose),7.81 mg/mL(medium dose),and 3.90 mg/mL(low dose)were selected,and a control group with ribavirin-positive drugs(1.25 mg/mL).The Yedahuang powder extrac inhibition effect against adherence and replication on Marc-145 cells,and its cytotoxicity were detected.The results showed that the Yedahuang powder extract had no side effects on the growth of Marc-145 at a dose of 31.25 mg/mL and below.Compared with the ribavirin control group,the Yedahuang powder extract has significant adsorption inhibition,replication inhibition,and direct inactivation effects to PRRSV-infected Marc-145 cells.The inhibition rate of PRRSV proliferation was above 80%.The titer of virus decreased 2 to 3 magnitudes after Yedahuang powder extract treatment,the difference is significant(P<0.05).Comparative transcriptomics data shows that Yedahuang powder extract can significantly up-regulate the expression of interferon-stimulating genes(ISGs).Flow cytometry showed that Yedahuang powder extract had significant anti-apoptosis and inducing G0/G1 phase block in the cell cycle.4 Therapy Effect of Yedahuang powder against PRRS in Clinical ApplicationFour pig feeding farms without immunization of PRRSV are marked as NT1,NT2,TZ1,and TZ2.Adopt the addition of Yedahuang powder to the feed for 14 consecutive days(treatment)or 21 days(prevention),and cooperate with comprehensive technical measures such as closing the herd,stopping introduction,strengthening biological safety,detection and elimination to evaluate the prevention and treatment effect of Yedahuang Powder on PRRS.The results showed that pregnant sows on NT-1 and NT-2 farms were protected,premature delivery was stopped,and the number of stillbirths was significantly reduced.On TZ-1 and TZ-2 farms,nursery pigs and fattening pigs suffered from cough and asthma.serum PRRSV antibody level S/P value,S/P mean value,standard deviation,dispersion,and other indicators all decreased.The PRRSV load was significantly down-regulated,and the cytokine IFN-y and IL-2 content were significantly increased,and the cytokine IL-10 content was significantly decreased(P<0.05).NT-1 and NT-2 abortion rate of pregnant sows have decreased significantly,and the percentage of healthy litter,the survival rate of piglets in the farrowing room,and the estrus rate of sows after weaning have significantly increased(P<0.05).The mortality has been significantly reduced in TZ-1 and Tz-2.Besides,production indicators such as average daily gain,the 70-day-old average weight of nursery pigs,and the 160-day-old average weight of fattening pigs all increased. |
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