Immunogenicity of a Hepatitis B Recombinant Vaccine Produced by Intituto Butantan among Children in Rio de Janeiro.

by Miguel, Juliana Custódio

Recently, the Instituto Butantan (São Paulo, Brazil) produced the first Brazilian recombinant vaccine against hepatitis B (BUTANG-BUT). To enlarge the existing data, the GPNI/FNS/MS promoted a multi-center study, carried out in 5 localities and among different age strata. As part of this project, we investigated the immunogenicity of BUT among children aged 1-10 years from Educandário Lar de Frei Luiz, Rio de Janeiro, during the period 2001-2002. Children were immunized with 3 doses (10ug) of BUT (N=219) or Engerix B (?EB?, Glaxo SmithKline Biologicals, N=264), following the schedule 0, 1, 6 months. Blood samples were collected prior to the first (C0) and 28-100 days after the third doses (C1). Detection of HBV markers was performed using immunoassays (BioMerieux) (C0) and anti-HBc was retested in C1. Anti-HBs titer was determined using a paramagnetic-particle chemiluminescent immunoassay (Access Ab HBs II, Beckman-Coulter) and seroprotection was defined as anti-HBs amp;#8805;10mUI/ml. Equivalence between vaccines was defined as i) a difference not larger than 5% between seroprotection proportions (BUT? EB) and ii) GMT-BUT/GMT-EB ratio gt;0.67. Seroprotection was observed in 100.0% and 97.7% of children, with GMTs of 3.600 mUI/ml and 2761 mUI/ml for BUT and EB, respectively. The difference between seroprotection proportions was 2.3% and GMT ratio was 1.3. During the project we evaluated different commercially assays to assess HBV vaccine response. A total of 163 samples were further tested using a microparticle enzyme immunoassay (IMx AUSAB, Abbott Laboratories) and a method based in EIA (ETI-AB-AUK-3, Diasorin). The tests presented concordant results (plt;0.01). We analyzed in pairs ? Access/IMx, Access/Diasorin and IMx/Diasorin. The linear coefficients were 0.960, 0.913 and 0.943, respectively. The highest correlation was among Access/IMx. These results showed that both vaccines are equivalent and suitable for use among children and that commercial assays are suitable for vaccine response evaluation.