Treatment using Kampo medicine (Keigai-rengyo-to or Seijo-bofu-to) for human metapneumovirus infection

抄録

Human metapneumovirus (hMPV) is a globally prevalent respiratory pathogen that primarily affects young children, older adults, and immunocompromised individuals. Since its discovery in 2001, hMPV has been recognized as a major cause of upper and lower respiratory tract infections, with clinical features resembling those of respiratory syncytial virus. Nearly all children are exposed by age five, and seasonal peaks occur in late winter to early spring in temperate regions such as Japan. Severe disease, including bronchiolitis and pneumonia, is most common in infants, the elderly, and immunocompromised patients. Although management is supportive care, no antiviral agents are currently licensed for hMPV. Ribavirin and remdesivir show in vitro antiviral activity, but their clinical efficacy remains uncertain. Recent in silico studies suggest that several herbal medicines may inhibit hMPV. Glycyrrhizin from Glycyrrhiza Radix binds strongly to the hMPV matrix (M) protein, while quercetin and rutin from Forsythia Fructus, epigallocatechin gallate from Camellia sinensis, and apigenin from Schizonepetae Spica exhibit binding affinity for the viral fusion (F) protein and/or nucleoprotein (N). In Japan, Kampo medicines containing these ingredients—particularly Keigai‑rengyo‑to and Seijo‑bofu‑to—may therefore have therapeutic potential. Further in vitro, in vivo, and clinical studies are required to evaluate their safety and efficacy as potential treatments for hMPV.