Figure 2. Type-specific protection against multiple serotypes.
Mice were passively immunized with type-specific (TS) or an equivalent amount of antisera generated to a heterologous serotype (HS) and challenged with 104 pneumococci of the serotype indicated below 4 hours later. CFU/animal was determined 24 hours post immunization. n≥6 mice per group. * P<0.05, ** P<0.01. The agglutinating effect of TS and HS anti-pneumococcal rabbit antiserum was tested for each challenge strain.