PROTECTION OF INFANT MICE FROM CHALLENGE WITH STREPTOCOCCUS-PNEUMONIAE TYPE 19F BY IMMUNIZATION WITH A TYPE 19F POLYSACCHARIDE PNEUMOLYSOIDCONJUGATE

The immunogenicity and protective efficacy of a conjugate of Streptoco ccus pneumoniae type 19F polysaccharide and a genetically toxoided der ivative,e of the pneumococcal toxin pneumolysin was investigated in an infant mouse model. The conjugate was administered to Balb/c mice dur ing pregnancy and/or lactation, and to their offspring during early in fancy. The anti-polysaccharide and anti-pneumolysin titres of the immu nized infant mice were significantly higher than those of non-immunize d controls. When the infant mice were challenged with type 19F pneumoc occi, the bacteria were cleared more effectively from the blood of imm unized mice than front that of control mice. The survival rate for the immunized mice was also significantly higher than that for the contro l group. These results indicate that highly protective anti-pneumococc al responses can be induced in infant mice by immunization with the co njugate during gestation or early infancy, and suggest a possible role for pneumolysoid-polysaccharide conjugates as human vaccine component s.