Abstract: Objective To study the possible mechanism and pathway of action through which Shufeng Jiedu capsules combat respiratory syncytial virus (RSV). Methods Sixty BALB/c mice were randomly divided into the normal control group, model control group, ribavirin positive control group, and high, medium and low dose groups of Shufeng Jiedu capsules, with 10 mice in each. All these groups were infected with RSV by nasal drops to establish pneumonia models except the normal control group. Four hours after infection, the drug was administered for four consecutive days, once a day by gavage. On the fifth day of the experiment, the mice were killed, the lung index was calculated, and lung tissues were taken for RT-PCR to detect the mRNA expressions of such genes as absent in melanoma 2 (AIM2), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), cysteine-aspartic protease 1 (Caspase-1), interleukin 18 (IL-18), and interleukin 1 beta (IL-1β). The expression levels of corresponding proteins were analyzed by Western Blot. Results Compared with the normal control group, the lung indexes of mice in the model control group were significantly increased (P<0.01), suggesting that RSV infection caused severe lung inflammation. Compared with the model control group, the lung indexes in all the other groups of Shufeng Jiedu capsules were significantly reduced, especially in the medium and high dose groups (P<0.01). Results of RT-PCR and Western Blot showed that the expressions of AIM2, ASC, pro-caspase-1, cleaved-caspase-1, pro-IL-18, cleaved-IL-18, pro-IL-1β and cleaved-IL-1β (P<0.05, P<0.01) were significantly reduced in the high dose group. Conclusion Shufeng Jiedu capsules can significantly inhibit lung inflammation caused by RSV infection and mitigate the damage to lung tissues by regulating the AIM2 inflammasome pathway.

Key words: Shufeng Jiedu Capsule, Respiratory Syncytial Virus(RSV), Inflammasome Signaling Pathway, Lung Inflammation, Absent in Melanoma 2（AIM2）