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Infection and Immunity, May 2000, p. 2692-2697, Vol. 68, No. 5
Sheffield Institute for Vaccine Studies,
Division of Child Health, Children's Hospital, and Division of
Molecular and Genetic Medicine, University of Sheffield, Sheffield,
United Kingdom
Received 16 November 1999/Returned for modification 21 December
1999/Accepted 2 February 2000
Previous studies in children have shown that Haemophilus
influenzae type b (Hib) polysaccharide conjugate vaccines can
reduce nasopharyngeal carriage of H. influenzae and provide
herd immunity and suggest that this effect is mediated through mucosal
antibodies. As this phenomenon may operate in other invasive bacterial
infections which are propagated by nasopharyngeal carriage, mucosal
antibody responses to meningococcal C conjugate and A/C polysaccharide vaccines were investigated. A total of 106 school children aged 11 to
17 years were randomized to receive a single dose of either conjugate
or polysaccharide vaccine in an observer-blind study. Before and at 1, 6, and 12 months after immunization, samples of unstimulated saliva
were collected and assayed by enzyme-linked immunosorbent assay for
group C polysaccharide-specific immunoglobulin A (IgA), IgA1, IgA2 and
secretory component, IgG antibodies, and total IgG and IgA. A subset of
serum samples were also assayed for specific IgA and IgG antibodies.
The concentrations of specific IgA and IgG in saliva were expressed
both as nanograms per milliliter and as nanograms per microgram of
total IgA or IgG. One month after immunization, significant increases
in antibody titers (both IgA and IgG) were observed in saliva in both
groups. There were significant subsequent falls in antibody titers by 6 months. Anti-meningococcal C-specific secretory component and IgA
antibody titers were closely correlated (r = 0.85, P < 0.001), but there was no significant correlation
between salivary and serum IgA titers, suggesting that IgA antibodies
are locally produced. Significant correlation was found between
salivary and serum IgG titers (r = 0.52, P < 0.01), suggesting that salivary IgG may be serum
derived. Compared with polysaccharide vaccine, the conjugate vaccine
induced significantly higher salivary IgG responses (P < 0.05), although there were no significant differences between
salivary IgA responses to the two vaccines. The conjugate vaccine
induced greater salivary IgG responses than a polysaccharide vaccine.
Both vaccines induced significant salivary IgA antibodies. Further
studies are needed to establish the functional significance of these
mucosal responses.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Mucosal Immune Responses to Meningococcal Group C
Conjugate and Group A and C Polysaccharide Vaccines in
Adolescents
*
Corresponding author. Mailing address: Division of
Child Health, Children's Hospital, Sheffield S10 2TH, United Kingdom.
Phone: (0044) (0) 114 2717419. Fax: (0044) (0) 114 2752505. E-mail:
q.zhang{at}sheffield.ac.uk.
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