PROTECTIVE EFFECT OF ASTRAGALI RADIX BY INTRAPERITONEAL INJECTION AGAINST JAPANESE ENCEPHALITIS-VIRUS INFECTION IN MICE

We examined the protective effect of Astragali Radix extracts (AE) by intraperitoneal injection against Japanese encephalitis virus (JEV) in fection in mice. A protective effect was observed by all four samples of AE used. However, the degree of effectiveness for each AE was diffe rent. The observed survival rates of the groups injected with sample A (from Shanhsi, Japanese name Sansei-syo) and sample D (from Hokkaido) extracts mere higher than 80% at 21 d after JEV inoculation. The grou ps injected with sample B (from Hopei, Japanese name Kahoku-syo) and s ample C (from Hsiahsi, Japanese name Sensei-syo) extracts had a 60% su rvival rate. The increase in hemagglutination inhibition antibody tite r was negligible in mice that survived 21 d after JEV inoculation. The antiviral effect of AE was examined by plaque assay in vitro, but no antiviral effect was shown. In mice injected with AE, the peritoneal e xudate cell (PEG) numbers increased significantly, compared to the con trol. In these PEG, active oxygen production was also high. Also the g roup as a whole displayed a high survival rate against JEV infection, these were so strong. From these results, we propose that the protecti ve effect of AE is dependent on a non-specific mechanism during the ea rly stage of infection, before it shifts to antibody production, and t hat PEC plays an important role.