FIG. 4.
Changes in the specificity of Block 2 antibodies. Typical patterns of changes in Block 2 specificity with time are illustrated by antibody reactivities of pairs of serum samples taken from donors 329 and 41. Antibody reactivity is expressed as the OD492, comparing preseason (April 1994) and postseason (November 1994) samples from each donor side by side. MSP-1 antigens are shaded by type, as shown in the key. Panel A shows a changeover from a narrow MAD20-type specificity to K1-type specificities. Panel B shows boosts of antibody responses to K1 and MAD20 types and also the acquisition of antibodies against the RO33 type.