Abstract: Objective To observe the therapeutic effects and mechanism of Chai Yin granules on a mouse model of the disease and syndrome of human coronavirus pneumonia caused by the lung-attacking damp-heat epidemic virus (LDEV).Methods Chai Yin granules (8.8, 4.4, 2.2 g/kg) were used to treat the model of the disease and syndrome of human coronavirus pneumonia caused by LDEV. The mechanism by which Chai Yin granules worked on the model was evaluated in terms of the manifestations of symptoms, lung inflammation, expressions of viral nucleic acid in lung tissue, contents of cAMP and PGE-2 in the hypothalamus, contents of inflammatory factors in lung tissue and the percentage of immune cells in peripheral blood. Results In the model control group, the body mass decreased, the intakes of food and drinking water decreased significantly, lying and inactivity increased until depression occurred in some cases, the hair was wet, the mice huddled in clusters, their reaction was slow, their appetite was poor, the stool was sticky in the first stage and dry in later stages. The above symptoms were significantly improved in high-, medium- and low-dose Chai Yin granule groups. Compared with the model control group, the lung index in high and medium dose groups decreased significantly, but the difference was not statistically significant (P>0.05). The inhibition rates of the lung index were 26.49% and 21.06%, respectively; The expression of viral nucleic acid in lung tissue of mice in the high dose group decreased significantly (P<0.05). The contents of PGE2 and CAMP in the three groups decreased significantly (P<0.05, P<0.01). The contents of IL-1β, CD14 and MDA in lung tissue of mice in the three groups decreased significantly, but the content of SOD increased (P< 0.05, P<0.01). The percentage of CD4 ⁺ T / CD8 ⁺ T in peripheral blood of mice in the low-dose group increased significantly (P<0.05).Conclusion Chai Yin granules have a significant therapeutic effect against the mouse model of the disease and syndrome of human coronavirus pneumonia caused by the lung-attacking damp-heat epidemic virus by reducing the lung index of model mice, decreasing the expression of virus nucleic acid in lung tissue, inhibiting the expressions of immune inflammatory factors, regulating the expressions of central factors of hypothalamic thermoregulation and the immune function of peripheral blood lymphocytes.

Key words: coronavirus pneumonia, Chai Yin granules, a combined model of the disease and syndrome, immune function, inflammatory factors