When BALB/c mice were treated with a
Kampo (Japanese herbal) medicine "
Sho-seiryu-to" (SST) (2 g/kg, 10 times) orally from 7 days before to 4 days after the
infection and infected with mouse-adapted influenza virus A/PR/8/34 by nasal site-restricted
infection, replication of the virus in the nasal cavity and spread of the virus to the lung were efficiently inhibited at 5 days after
infection in comparison with water-treated mice. However, another
Kampo medicine "
Kakkon-to" showed no anti-influenza virus activity in the same condition. The
antiviral IgA antibody in the nasal and broncho-alveolar washes of the SST treated mice increased significantly in comparison with that of water-treated control.
Oral administration of SST (2 g/kg, 18 times) from 7 days before to 13 days after vaccination also significantly augmented serum hemagglutination-inhibiting antibody by nasal inoculation of
influenza HA
vaccine (5 micrograms/mouse) that was insufficient to induce
antiviral antibody. SST did not inhibit the replication of mouse-adapted influenza virus A/PR/8/34 in Madin-Darby canine kidney cells. SST also did not inhibit the influenza virus
sialidase activity against
sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate and hemagglutination by mouse-adapted influenza virus A/PR/8/34. SST showed no influence on
interferon production in nasal wash of mice at 5 days after the
virus infection. These results suggest that SST confers better protection against influenza virus
infection through augmentation of production of
antiviral IgA antibody but not direct action to the virus, and can be used as an adjuvant to nasally inoculated
influenza HA
vaccine.