Active substances from hot water extracts from 267 different Chinese and Japanese medicinal herbs were screened for mucosal adjuvant activity with
influenza HA
vaccine in mice. The extract from the root of Polygala tenuifolia was found to contain potent mucosal adjuvant activity. The active substances were purified and identified as onjisaponins A, E, F, and G. When each onjisaponin (10 microg) was intranasally (i.n.) inoculated with
influenza vaccine (10 microg) in mice, serum hemagglutination-inhibiting (HI) antibody titers increased 3-14 times over control mice administered
vaccine alone after 4 weeks. When each onjisaponin (10 microg) was i.n. inoculated with the
vaccine (10 microg) followed by i.n. vaccination of the
vaccine alone after 3 weeks, serum HI antibody titers increased 27-50 fold over those mice given i.n. vaccinations without onjisaponins. These same conditions also significantly increased nasal anti-influenza virus
IgA antibody titers. Two inoculations with
onjisaponin F (1 microg) and
influenza HA
vaccine (1 microg) at 3 weeks intervals, significantly increased serum HI antibody and nasal anti-influenza virus
IgA and
IgG antibody titers after only 1 week over mice given HA
vaccine alone after the secondary vaccination. Intranasal vaccination with
onjisaponin F inhibited proliferation of mouse adapted influenza virus A/PR/8/34 in bronchoalveolar lavages of infected mice. Separate intranasal vaccinations with onjisaponins A, E, F, and G (10 microg) each and
diphtheria-
pertussis-
tetanus (
DPT) vaccine (10 microg) of mice followed by i.n. vaccination with
DPT vaccine alone after 4 weeks showed significant increases in serum
IgG and nasal
IgA antibody titers after 2 weeks following secondary vaccination over mice vaccinated with
DPT vaccine alone. All onjisaponins showed little hemolytic activity at concentrations up to 100 microg/ml. The results of this study suggest that onjisaponins may provide safe and potent adjuvants for intranasal inoculation of
influenza HA and DPT
vaccines.