Study On The Safety And Antiviral Effect Of A Compound Chinese Medicine

Objective:To study the antiviral effect of a compound Chinese medicine on artificial infection of infectious bronchitis in chicks,in order to provide evidence for the development of new antiviral drugs.Methods:(1)To evaluate the safety of a compound Chinese medicine on target animal(chickens),100 healthy ISA Brown Roosters(8 days of age)were divided into 5 groups randomly(20 Roosters/group).Each group was given a compound Chinese medicine with water based on the recommended dosage,that is for first group we use the standard recommended dosage(4g/L),for 2nd group 3 times of the recommended dosage(12g/L),3rd group 5 times of the recommended dosage(20g/L)and 4th group has given 10 times of the recommended dosage(40g/L)for 5 days continuously while the 5th group,the control one,were given no medicine with water.General clinical examination such as condition of the chicken,feed and water intake as well as fecal examination were observed on daily basis.On the 6th day of treatment,Body weight,hematology and blood biochemical analysis,Visceral index and histopathological examination were performed.(2)In order to study the therapeutic effect of a compound Chinese medicine on avian infectious bronchitis(IB).we measure the EID50 of infectious bronchitis virus,strain M41 from SPF chicken embryos to determine the challenge dose.We then select 360 roosters(8 days of age)and divided them into 6 groups according to their weight.Except from the blank control group,all the roosters were challenged with 0.2 ml(104.27EID50 IBV)of the 3rd generation chicken embryo allantoic fluid for 72h.Out of the total six groups,the three Treatment groups were treated with 2 g/L,4 g/L and 8 g/L a compound Chinese medicine respectively in drinking water;the drug control group were given 25 g/kg feed Maxingshigan Powder continuous for 5 days;the blank control group(free of virus and drug)and the virus control group(have virus but no treatment).The antiviral effect,mean weight gain,immune organ index,target organ viral load,IFN-?expression in the trachea and histopathology were observed.Results:(1)In the safety test of target animals,there was no significant difference in weight gain,organ index,blood routine indicators,serum biochemical indicators and histopathological observation between the experimental chickens and the blank control group.(2)In this experiment,all the roosters were challenged with 0.2 ml(104.27EID50 IBV)of the 3rd generation chicken embryo allantoic fluid for 72h.Observed typical clinical symptoms and pathological changes of IB and IBV-N genes were detected by PCR.The results showed that the IB disease model was successfully constructed.(3)The clinical trials showed that the percent efficacy of high and medium dose a compound Chinese medicine were 90.00%and 86.67%,the cure rates were 80.00%and 76.67%and the mortality was 10.00%and 13.33%respectively;It can promote chicken weight gain and immune organ development,and significantly improve histopathological changes.(4)The IBV N gene expression in the lungs,trachea and bronchus of each treatment group is significantly lower than that in the virus control group(p<0.05),Compared with the virus control group,each drug group significantly reduced the expression of IBV N gene in the trachea,bronchus and lungs of chickens(p<0.05),compared with the positive control drug MaxingShigan Powder group,each drug group the expression of IBV N gene in trachea,bronchus and lung was not significantly different(p>0.05).(5)The IFN-? expression in the trachea of each treatment group was detected.Compared with the virus control group,the IFN-? expression of high and middle dose groups of a compound Chinese medicine is significantly increased(p<0.05),which was better than MaxingShigan Powder group(p>0.05).compared with the positive control drug MaxingShigan Powder group,high dose group could significantly up regulate the expression of IFN-?(p<0.05),compared with other drug groups,there was no significant difference(p>0.05).Conclusion:1.a compound Chinese medicine at dosage of 4g/L,12g/L,20g/L and 40g/L respectively in drinking water,continuous for 5 days,did not show any adverse effects on the tested chickens compared with the control group.All the results showed that the a compound Chinese medicine were safe for chickens.2.High doses group of a compound Chinese medicine(8 g/L water)and medium doses group of a compound Chinese medicine(4g/L water)have a significant therapeutic effect on artificially infected IB.