Coimmunization of mice with HBsAg and various Id proteins.

Mice were immunized twice intraperitoneally with a mixture of 2 μg HBsAg and 10 μg Id, Id-GM, or Id-CTLA4. Sera were collected 2 weeks after the second immunization. Anti-Id (A) and anti-HBsAg (B) titers were determined by ELISA, as described in “Materials and methods.” The data are presented as the mean ± SD for 5 animals in each group.