Antinicotine antibody titers in mice after HexonAM1 vaccine administration. C57Bl/6 mice (n=8/group) were sensitized to nicotine (0.5 mg/kg) or to phosphate-buffered saline (PBS), daily 10 times over 2 weeks, followed by immunization intramuscularly with 4 μg of HexonAM1 vaccine at 2, 5, 8, and 17 weeks. (A) Levels of antinicotine antibodies following HexonAM1 vaccination. (B) Antibody IgG isotype titers evoked by the HexonAM1 vaccine.