The antiviral effect of keishi-ni-eppi-ichi-to, a traditional Chinese herbal medicine, on influenza A2(H2N2) virus infection in mice.

The antiviral effect of Keishi-ni-eppi-ichi-to (TJS-064), a traditional Chinese herbal medicine, was investigated in mice infected with influenza A2(H2N2) virus. When mice exposed to a 5 LD50 dose of the virus were treated orally with a 70 mg/kg dose of TJS-064 1 day before and 1 day and 4 days after the infection, 100% survived over a 25-day experimental period. At the end of this period all the control mice, treated with saline alone, had died; their mean survival time in days (MSD) was 11.2 days. When mice infected with a 10 LD50 dose of the virus were treated with TJS-064, the MSD was > 17.4 days and there was a 50% survival rate, while the control group had a MSD of 8.7 days and a 0% survival rate. No significant antiviral effect of TJS-064 was observed when the agent was administered orally to mice infected with a 100 LD50 or larger dose of influenza virus. Pulmonary consolidations, virus titers in lung tissues and HAI titers in sera of infected mice treated with TJS-064 were all significantly lower than those of infected mice treated with saline. Interferon activities were detected in sera of mice treated with the agent at a dose of 100 mg/kg orally. Since viricidal and viristatic activities of the agent against influenza virus were not demonstrated, the antiviral effects of TJS-064 may be expressed through the host's antiviral functions including interferon production.