CHARACTERIZATION OF IMMUNE-RESPONSE AS AN INDICATOR OF HAEMOPHILUS-INFLUENZAE TYPE-B VACCINE EFFICACY

Quantitation of antibodies to Haemophilus influenzae type b (Hib) poly saccharide has been an active area of investigation associated with th e development of polysaccharide and subsequently polysaccharide-protei n conjugate vaccines. These clinical studies indicate that there are s everal serologic parameters associated with Hib vaccine efficacy in in fants. Efficacious vaccines elicit polysaccharide-specific antibodies in infants; they prime the immune system for an anamnestic response; t he immune response is long-lived through the period of greatest risk f or disease; and the elicited antibodies have functional activity as de monstrated in bactericidal and opsonophagocytic assays or protection i n an infant rat challenge model. The immune response to different Hib vaccines varies both quantitatively and qualitatively. With the introd uction of routine Hib vaccine immunization, vaccine performance can re ly on these serologic parameters. Quantitative serologic assays, the r adio-antigen binding and enzyme-linked immunosorbent assays, have been developed and standardized. The quality of the antigen as well as opt imization of all assay steps and reagents are key to ensuring specific and reproducible antibody quantitation.