Salivary immune responses to the 7-valent pneumococcal conjugate vaccine in the first 2 years of life.
BACKGROUND
The CRM197-conjugated 7-valent pneumococcal vaccine (PCV7) is protective against vaccine serotype disease and nasopharyngeal carriage. Data on PCV7-induced mucosal antibodies in relation to systemic or natural anticapsular antibodies are scarce.


METHODS
In a randomized controlled setting, children received PCV7 at age 2 and 4 months (2-dose group), at age 2, 4 and 11 months (2+1-dose group) or no PCV7 (control group). From 188 children paired saliva samples were collected at 12 and 24 months of age. From a subgroup of 15 immunized children also serum samples were collected. IgG and IgA antibody-levels were measured by multiplex immunoassay.


RESULTS
At 12 months, both vaccine groups showed higher serum and saliva IgG-levels against vaccine serotypes compared with controls which sustained until 24 months for most serotypes. Salivary IgG-levels were 10-20-fold lower compared to serum IgG, however, serum and saliva IgG-levels were highly correlated. Serum and salivary IgA-levels were higher in both vaccine groups at 12 months compared with controls, except for serotype 19F. Higher salivary IgA levels remained present for most serotypes in the 2+1-dose group until 24 months, but not in the 2-dose group. Salivary IgA more than IgG, increased after documented carriage of serotypes 6B, 19F and 23F In contrast to IgG, salivary IgA-levels were comparable with serum, suggesting local IgA-production.


CONCLUSIONS
PCV7 vaccination results in significant increases in salivary IgG and IgA-levels, which are more pronounced for IgG when compared to controls. In contrast, salivary anticapsular IgA-levels seemed to respond more to natural boosting. Salivary IgG and IgA-levels correlate well with systemic antibodies, suggesting saliva might be useful as potential future surveillance tool.
Department of Pediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.
Gerwin D
GD
Rodenburg
Elisabeth A M
EA
Sanders
Elske J M
EJ
van Gils
Reinier H
RH
Veenhoven
Tomasz
T
Zborowski
Germie P J M
GP
van den Dobbelsteen
Andries C
AC
Bloem
Guy A M
GA
Berbers
Debby
D
Bogaert
D000917:Antibody Formation; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007223:Infant; D008297:Male; D011008:Pneumococcal Infections / Q000276:immunology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology / Q000627:therapeutic use*; D012463:Saliva / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology; D014611:Vaccination; D018074:Vaccines, Conjugate / Q000276:immunology / Q000627:therapeutic use*
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate