The antibody response to P. berghei ANKA in BALB/c and BALB.B6-Cmv1r mice. BALB/c and BALB.B6-Cmv1r mice were infected with P. berghei. Serum samples were collected at different time points p.i., and parasite-specific IgM (A) and IgG (B) antibody responses or total IgM (C) and IgG (D) contents were analyzed by ELISA as indicated in Materials and Methods. Each point represents the mean of 8 to 10 samples ± the standard error. *, P < 0.05; **, P < 0.01; ***, P < 0.005; ****, P < 0.001.