Objective To study the effects and possible mechanism of Qingqi Jiedu Decoction（清气解毒方）against respiratory syncytial virus（RSV）.Methods Three New Zealand white rabbits were divided into blank serum group

ribavirin group and Qingqi Jiedu Decoction group

with 1 rabbit in each group.The Qingqi Jiedu Decoction group was administered with 36.32 mg/（kg · d） Qingqi Jiedu Decoction

the ribavirin group was given18.24 mg/（kg·d） ribavirin

and the blank serum group was given 50 ml normal saline.The drug-containing serum was prepared after continuous administration for 3 days.The half-infection of RSV（TCID50） was detected and the maximum non-toxic concentration of Qingqi Jiedu Decoction and ribavirin was screened for subsequent experiments.Hep-2 cells were seeded in 96-well plates at 1×10

5

/ml

and were divided into cell group

virus group

ribavirin group and Qingqi Jiedu Decoction group

with 6 duplicate wells in each group.The ribavirin group was added with ribavirin serum

the Qingqi Jiedu Decoction group was added with Qingqi Jiedu Decoction serum

and the cell group as well as virus group were added with the cell maintenance solution.After 48

72

and 96 hours of culture

the virus inhibition of each group was detected.After 96 hours

the cell cycle and apoptosis rate of each group were observed.Results The respiratory syncytial virus A subtype（Long strain） had a TCID50 of 10-4.581/100 μl.The concentration of 40% Qingqi Jiedu Decoction drug-containing serum was screened out as its maximum cell non-toxic concentration（0.363 g/ml）

and the concentration of 50% ribavirin-containing serum was screened out as its maximum cell nontoxic concentration（0.228 mg/ml）.Compared with the cell group

the OD value of the virus group was significantly decreased at 48

72 and 96 hours after infection（P

<

0.01）.Compared with the virus group

the OD values of the ribavirin group and the Qingqi Jiedu Decoction group were significantly increased at 48

72

and 96 h（P

<

0.05 or P

<

0.01）.The virus inhibition rates of Qingqi Jiedu Decoction group were 42.1%

57.0%

and 66.6% at 48

72

and 96 h

respectively

which were lower than 51.2%

69.6%

and 77.3% of the ribavirin group.Compared with the cell group

the G1 phase of the virus group was significantly increased

the S phase was significantly decreased

and the apoptotic rate was also increased（P

<

0.05 or P

<

0.01）.Compared with the virus group

the G1 phase of the ribavirin group and the Qingqi Jiedu Decoction group was significantly decreased

the S phase and the G2 phase were significantly increased

and the apoptotic rate was also decreased（P

<

0.05 or P

<

0.01）.Conclusion Qingqi Jiedu Decoction has a certain anti-RSV effect in vitro

and the effect is slightly worse than ribavirin.