Screening Of Anti-swine Influenza Virus Traditional Chinese Medicine Ingredients In Vitro

Swine influenza (SI) is an acute respiratory disease caused by swine influenza virus(SIV), which can seriously affect swine industry. It is one of infectious diseases thatprevalently exist in large scale livestock farm. This disease is characterized by its highmorbidity and low mortality. The severity of this disease largely depends on secondaryinfection by other bacteria or viruses which will lead a higher mortality. Moreover, the pigscan serve as an intermediate host of interspecies transmission of influenza virus. So theresearch of SI plays a significant role in the public health implications.Nowadays, thevaccines and antiviral drugs treatments are the two main methods against SIV. However, dueto the flu virus’ amazing variability and drug resistance, the control of SI is faced with severetest. It’s important for swine industry to screen effective traditional Chinese medicine (TCM).The purpose of this study is to screen TCMs which have an effect on influenza virus.Research results will be useful for further study and experiment.Methods:In this experiment SIV infectious model with MDCK cell was built up in vitrofirstly. The active ingredients of TCMs were extracted in the way of water decocting. TheTCMs were prepared to a final concentration of0.5g/ml water extracts, respectively. Themaximum safe concentration of herbs was determined by observing the morphology of cellsand the integrity of cell monolayer. Through using drugs before and after the infection,first-time screening tests were carried out. By changing the dosage and time, the antiviralmechanism of drugs were discussed. The minimum effective concentration was determinate.Results show that the maximum safe concentration of most drugs is range from15.62mg/ml to3.90mg/ml. In the first-time,13kinds of drugs were tested to have antivirusactivity, they are as follows: bupleurum, dandelion, andrographis paniculata, sophoraflavescens, Amur Corktree Bark, herba violae, herba taching, capillary Artemisia,chrysanthemum, Scutellaria baicalensis, pulsatilla, forsythia suspense, asarum. Theinvestigation of mechanism of antiviral action shows that:(1)The following drugs can resistto virus adsorption, which is more effective than ribavirin: Andrographis paniculata, sophoraflavescens, Amur Corktree Bark, herba taching, forsythia suspense.(2)12kinds of drugs can interfere virus replication, such as: bupleurum, dandelion.(3) When the drugs and viruscontact cells at the same time,11kinds of drugs have an effect on virus such as bupleurumand dandelion.6kinds of them are more effective than ribavirin, such as dandelion andsophora flavescens(.4)10kinds of drugs can directly anti-virus effect such as bupleurum anddandelion. Among these, bupleurum and sophora flavescens are more effective than ribavirin.The drugs’ minimum concentration is range from0.06mg/ml to7.8mg/ml. And the minimumconcentration of Scutellaria baicalensis is lowest,0.06mg/ml. The therapeutic index(TI) ofthese drugs is from1to32, in which Scutellaria baicalensis is32, the highest one.