PROTEIN-CONJUGATED SYNTHETIC DISACCHARIDE AND TRISACCHARIDE OF PNEUMOCOCCAL TYPE 17F EXHIBIT A DIFFERENT IMMUNOGENICITY AND ANTIGENICITY THAN TETRASACCHARIDE

Overlapping synthetic disaccharide, trisaccharide and tetrasaccharide, derived from pneumococcal polysaccharide type 17F (PS17F), were coupl ed to keyhole limpet haemocyanin (KLH). The conjugates were tested in mice. The disaccharide-KLH and especially trisaccharide-KLH, in combin ation with Quil A, induced high titres of high-avidity anti-PS17F IgG. Both conjugates protected mice against challenge with Streptococcus p neumoniae 17F. Tetrasaccharide-KLH, although able to elicit anti-tetra saccharide antibodies, induced a minimal non-protective anti-PS17F IgG response of low avidity. The tetrasaccharide-KLH conjugate, in contra st to the other conjugates, failed to bind rabbit anti-PS17F IgG.