An oligosaccharide-tetanus toxoid conjugate vaccine against type III group B Streptococcus.
We have developed an oligosaccharide-tetanus toxoid conjugate vaccine against type III group B Streptococcus. Purified group B streptococcal type III capsular polysaccharide was depolymerized by enzymatic digestion using endo-beta-galactosidase produced by Citrobacter freundii. Following enzymatic digestion, oligosaccharides were fractionated by gel filtration chromatography on Sephadex G-75. An oligosaccharide pool of average Mr = 14,500 (corresponding to 13.6 repeating units of the type III polysaccharide) was used for conjugation to tetanus toxoid. Tetanus toxoid was covalently coupled via a synthetic spacer molecule to the reducing end of the oligosaccharide by reductive amination. The oligosaccharide-tetanus toxoid conjugate elicited type III-specific anticapsular antibodies (measured in enzyme-linked immunosorbent assay) in three out of three rabbits whereas the unconjugated native type III polysaccharide was nonimmunogenic. Antiserum from rabbits vaccinated with the oligosaccharide-protein conjugate protected mice against lethal challenge with live group B streptococci (16 out of 16 mice survived) and opsonized group B streptococci for phagocytosis in vitro. No protection was conferred by preimmune serum nor by serum from rabbits vaccinated with unconjugated native type III polysaccharide. An oligosaccharide-protein conjugate vaccine of this design may prove to be an effective immunogen for protection against group B streptococcal infection in humans. In addition, the approach to vaccine design utilized in these studies will facilitate further definition of the structural parameters that determine immune response to glycoconjugate vaccines.
Paoletti
L C
LC
Channing Laboratory, Brigham and Women's Hospital, Boston, Massachusetts 02115.
Kasper
D L
DL
Michon
F
F
DiFabio
J
J
Holme
K
K
Jennings
H J
HJ
Wessels
M R
MR
D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D001428:Bacterial Vaccines; D006026:Glycoside Hydrolases; D007114:Immunization; D051379:Mice; D009844:Oligosaccharides / Q000276:immunology* / Q000302:isolation & purification; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000276:immunology*; D011817:Rabbits; D013292:Streptococcus agalactiae / Q000276:immunology*; D013745:Tetanus Toxoid; D001616:beta-Galactosidase / Q000378:metabolism
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D013745:Tetanus Toxoid; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase