Figure 3. Protection in B cell–deficient mice.

To define the role of B cells in protection following immunization, B cell–deficient (μMT) or B cell–sufficient (B6) mice were immunized with 10³ (AS) prbc in CpG-ODN or control ODN. 2 weeks later, mice were challenged i.v. with 10⁵ homologous (AS) prbc and (A) parasitemia or (B) disease severity monitored. Disease severity was assessed by determining clinical scores (C). Data for individual mice are shown and are representative of 3 independent experiments. Note that mice of B6 background (B6 or μMT) are naturally resistant to P. c. chabaudi AS and thus, protection was determined by reduced parasitemia and disease severity. ms1, mouse 1.