PROTECTIVE EFFECT OF ASTRAGALI RADIX BY ORAL-ADMINISTRATION AGAINST JAPANESE ENCEPHALITIS-VIRUS INFECTION IN MICE

We investigated the protective effect of Astragali Radix (AR) by oral administration against Japanese encephalitis virus (JEV) infection in mice, the pharmacological effects of AR extracts (AE) in different ori gin, and the chemical composition of the AEs. A protective effect mas demonstrated in all four AEs used, however, the effective grade for ea ch one was different. In the control group, an increase of hemagglutin ation inhibition (HT) antibody titer was observed in all mice survivin g 25 d after JEV inoculation. However, the increase of HT antibody tit er was not observed in some animals administered an AE. In the control group, the rate of HI antibody positive mice was 90% 3 d after JEV in oculation, while the four groups which received the AE had a 30-60% po sitive rate. In mice,which received the AE, the peritoneal exudate cel l (PEG) numbers increased significantly compared to the control group. The predominant cell population of PECs in mice receiving the AE was macrophages, and in the PEG, the active oxygen (AO) production was hig h. From these results, me propose that the protective effect of AE by oral administration is based on a non-specific mechanism during the ea rly stage of infection, before shifting to antibody production, and th at macrophages play an important role in this resistance to JEV infect ion, e.g., by inducing the production of AO. In the chemical compositi on of each AE, carbohydrate was the major component.