Although respiratory syncytial virus (RSV) is a major cause of
respiratory tract infection in children, no effective
therapies are available. Recently, RSV G, the attachment
glycoprotein, has become a major focus in the development of therapeutic strategies against
RSV infection. Treatment of RSV-infected cultured cells with
maoto, a traditional herbal medicine for acute febrile diseases, significantly reduced the
viral RNA and titers. RSV attachment to the cell surface was inhibited both in the presence of
maoto and when RSV particles were pre-treated with
maoto. We demonstrated that
maoto components,
Ephedrae Herba (EH) and Cinnamomi Cortex (CC), specifically interacted with the central conserved domain (CCD) of
G protein, and also found that this interaction blocked viral attachment to the cellular receptor CX3CR1. Genetic mutation of CX3C motif on the CCD, the
epitope for CX3CR1, decreased the binding capacity to EH and CC, suggesting that CX3C motif was the target for EH and CC. Finally,
oral administration of
maoto for five days to RSV-infected mice significantly reduced the lung viral titers. These experiments clearly showed the anti-RSV activity of EH and CC mixed in
maoto. Taken together, this study provides insights for the rational design of
therapies against
RSV infection.