title: Measles vaccination in the presence of maternal antibodies primes for a balanced humoral and cellular response to revaccination.
abstract: Early or low dose antigen exposure can prime the immune system for subsequent responses; the so-called "prime-boost" effect. In the context of a Sudanese measles vaccine trial, we assessed whether or not such early exposure could influence the response to revaccination. Children received either Connaught high titer vaccine (CN: n = 53; 10(4.7)pfu) or meningococcal A + C vaccine as a placebo (MEN: n = 58) at 5 months of age. At 9 months of age, all received standard titer Schwarz vaccine (SCH: 10(3.9)pfu). Neutralizing antibodies were measured before initial vaccination and at 9 months of age (plaque reduction neutralization assay (PRN)) and again at 5 years of age (syncytium inhibition assay (SIA)). Lymphoproliferative responses to measles virus (MV) antigens were evaluated at 5 years of age. Eleven of the 53 CN-SCH children (21%) had sub-protective neutralizing antibody titers prior to revaccination (log PRN 1.5 +/- 0.03 versus 2.9 +/- 0.07 in the remaining 42 children; P < 0.004). Maternal antibody titers at the time of initial vaccination in these 11 were high (PRN 2.44 +/- 0.12 versus 1.9 +/- 0.04; P < 0.0001). At 5 years of age, neutralizing antibodies were comparable in the 11 CN-SCH poor responders (log SIA 2.1 +/- 0.09), the remaining CN-SCH children (2.2 +/- 0.06) and the MEN-SCH group vaccinated only once at 9 months of age (2.25 +/- 0.06). In contrast, 7/11 of the CN-SCH poor responders (64%) had stimulation indices (SI) > 3 in response to MV antigens at 5 years of age (SI 3.1 +/- 0.6) compared with only 14% in the remaining children of the CN-SCH group (2.0 +/- 0.3; P = 0.05) and 8% in the MEN-SCH group (1.4 +/- 0.2; P < 0.0003). These data suggest that early measles vaccination in the presence of maternal antibodies can sometimes prime for a balanced humoral and cellular immune response to subsequent revaccination.
authors.affiliation: Center for the Study of Host Resistance, Montreal General Hospital, McGill University, 1650 Cedar Avenue, Montreal, QC, Canada H3G 1A4.
authors.forename: F M N
authors.initials: FM
authors.lastname: Bertley
authors.forename: S A
authors.initials: SA
authors.lastname: Ibrahim
authors.forename: M
authors.initials: M
authors.lastname: Libman
authors.forename: B J
authors.initials: BJ
authors.lastname: Ward
mesh_terms: D000367:Age Factors; D000914:Antibodies, Viral / Q000097:blood*; D000917:Antibody Formation; D002675:Child, Preschool; D006801:Humans; D007111:Immunity, Cellular; D007112:Immunity, Maternally-Acquired; D007223:Infant; D008214:Lymphocytes / Q000276:immunology; D008458:Measles Vaccine / Q000008:administration & dosage / Q000276:immunology*; D009500:Neutralization Tests; D013397:Sudan
chemical_list: D000914:Antibodies, Viral; D008458:Measles Vaccine