Treatment using Kampo medicine (Keigai-rengyo-to, Seijo-bofu-to) for Nipah virus infection

抄録

Nipah virus (NiV) is an enveloped, negative‑sense RNA virus of the genus Henipavirus that causes severe respiratory and neurological disease with case fatality rates often exceeding 40–75%. Its six structural proteins—N, P, M, F, G, and L—coordinate genome encapsidation, RNA synthesis, virion assembly, and host‑cell entry via ephrin‑B2/B3 receptors. Natural reservoirs in Pteropus bats enable repeated spillover, with human outbreaks documented in Malaysia, Singapore, Bangladesh, and other countries. Although management remains supportive and no licensed antiviral therapy exists, several repurposed agents, including remdesivir and favipiravir, show preclinical antiviral activity, and the monoclonal antibody m102.4 has been used under compassionate protocols. In silico studies further suggest that multiple phytochemicals—such as berberine, diosgenin, betulinic acid, quercetin, kaempferol, apigenin, luteolin, naringin, EGCG, and others—bind NiV F, G, M, N, and P proteins with inhibitory potential. Many of these compounds are present in Kampo medicines (KMs), including Keigai‑rengyo‑to (KRT), Seijo‑bofu‑to (SBT), Senkyu‑chacho‑san , and Sho‑saiko‑to. Because KRT and SBT contain multiple herbs rich in NiV‑targeting phytochemicals, they may offer comparatively stronger therapeutic potential. Rigorous in vitro, in vivo, and clinical studies are required to validate KM efficacy and safety. If confirmed, combining KMs with established agents such as remdesivir could provide a practical multidrug strategy for future NiV outbreaks.