ISSN:
1432-1076
Keywords:
Key words Haemophilus influenzae type b
;
Combination vaccine
;
Immunological memory
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The lack of an adequate immune response to the major polysaccharide of the Haemophilus influenzae type b (Hib) capsule (polyribosyl ribitol phosphate) (PRP) in very young infants (〈 18 months) can be overcome by conjugating PRP to a T-cell dependent carrier protein. We studied whether administration of a tetanus-PRP conjugate vaccine reconstituted with a diphtheria-tetanus-acellular pertussis-hepatitis B (DTPa-HBV) vaccine as a three dose primary course at 3, 4 and 5 months of age induced PRP-specific immunological memory, by examining the anti-PRP response to a dose of unconjugated PRP given with the DTPa-HBV booster approximately 1 year later. The unconjugated PRP elicited protective anti-PRP antibody levels (≥ 0.15 μg/ml) in all but 3 of the 369 vaccinees, including 13 infants who failed to demonstrate a measurable immune response after the primary course. In a sub-cohort of 54 subjects all had anti-PRP levels ≥ 0.5 μg/ml within 7–14 days of the booster showing a rapid anamnestic type response. Both primary and booster responses were predominantly IgG1 indicating a T-cell dependent response. The DTPa-HBV components elicited protective anti-diphtheria, anti-tetanus and anti-HBs antibody levels in ≥ 98.5% of vaccinees, and immune responses to each of the acellular pertussis vaccine components in 92.3%–97.3% of subjects. Conclusion The tetanus-PRP conjugate vaccine not only elicited a good primary humoral response, but also induced immunological memory so that the infants were able to mount a large and rapid immune response to subsequent exposure to plain PRP, indicating that protection against circulating wild-type Hib had been generated. Successful induction of immunological memory occurred even when there was no measurable humoral anti-PRP response to the primary course. Tetanus-PRP conjugate vaccine can be used in combination with DTPa-HBV vaccine, when administered separately or as a single injection in the same syringe, in primary immunisation schedules at 3, 4 and 5 months of age.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004310050544
