2026 Volume 77 Issue 1 Pages 9-21
Female BALB/c mice (8 weeks old) were infected with mouse-adapted influenza virus A/PR/8/34 (H1N1) by droplet exposure. They were then orally administered a Kampo (traditional Japanese herbal) medicine, saikatsugekito decoction (SKGT, 1.0 g/kg/day) for 6 days starting from the day of infection. Lung tissue was collected and analyzed 6 days post-infection. The results showed that the general condition score and pulmonary gross lesion score were significantly reduced in the SKGT-treated group compared to the solvent-treated (control) group. In addition, viral titers in the lungs were significantly lower in the SKGT-treated group, indicating suppression of viral proliferation. Furthermore, proinflammatory cytokines (IL-6 and TNF-α) in the lungs were significantly reduced by SKGT treatment. SKGT significantly increased the gene expression levels of factors involved in the production of interferon (IFN)-stimulated genes (ISGs) in the early innate immune response of the lungs, as well as multiple ISGs. These results suggest that SKGT exerts antiviral activity that enhances the production of type I IFN by activating the innate immune system and inhibits proliferation of influenza virus in the lungs.
