PENTAVALENT PNEUMOCOCCAL OLIGOSACCHARIDE CONJUGATE VACCINE PNCCRM IS WELL-TOLERATED AND ABLE TO INDUCE AN ANTIBODY-RESPONSE IN INFANTS

Background, The emergence of resistant pneumococci makes the treatment of pneumococcal diseases difficult, The currently available polysacch aride vaccines have very limited efficacy in young children, The immun ogenicity can be improved by covalent coupling to protein carriers as has been shown with Haemophilus influenzae type b. Methods, Thirty hea lthy infants were immunized with a pneumococcal conjugate vaccine at 2 , 4 and 6 months of age, Oligosaccharides were derived from capsular p olysaccharides of types 6B, 14, 18C, 19F and 23F and conjugated to the nontoxic mutant diphtheria toxin CRM(197). The final vaccine was a mi xture of these conjugates, containing 10 mu g of each oligosaccharide, The infants received simultaneously H. influenzae type b oligosacchar ide-CRM(197) conjugate vaccine, Serum samples were taken before each d ose and 1 month after the third dose. Control material was composed of 25 serum samples taken from children of the same age without pneumoco ccal vaccination, Enzyme-linked immunosorbent assay was used to measur e serum IgG anti-pneumococcal polysaccharide concentrations and radioi mmunoassay for the serum Ig anti-H, influenzae type b concentrations,R esults, PncCRM vaccine was well-tolerated. Pneumococcal type 18C induc ed a significant antibody increase after the first dose, whereas the o ther five oligosaccharides, including H. influenzae type b oligosaccha rides, induced an increase after the second or third dose, The specifi c IgG concentrations at 7 months of age were significantly higher amon g the vaccinated infants than in the controls for all the five pneumoc occal types. Conclusions, Pneumococcal oligosaccharide-CRM(197) conjug ate vaccine is able to induce an IgG serum response in infants and ant i-pneumococcal antibody concentrations were significantly higher than in controls of same age.