XXXV Reunião Anual da SBBqResumoID:8180


Timing the booster to enhance antibody production and selectivity by mice immunized with liposomal formulation prepared within different pHs.


Vanessa de Almeida Silvaa, d, Célia Sayoko Takatab, Osvaldo A. Sant’AnnaC, Antônio Carlos Lopes d, and Maria Helena Bueno da Costaa



aLab. de Microesferas e Lipossomas – C. de Biotecnologia; bDivisão de Desenvolvimento Tecnológico e Produção and cLab. Especial de Microbiologia-. Instituto Butantan,

Av. Vital Brasil, 1500, 05503-900 – Butantan, São Paulo, SP, Brasil

dDisciplina de Clínica Médica, Departamento de Medicina – Universidade Federal Paulista,

Rua Pedro de Toledo 980, São Paulo, SP

 


The Dtxd (Diphtheria toxoid) was the first antigen encapsulated within liposomes, when was so discovered their adjuvant properties that means their capacity to enhance the vaccine immunogenicity. The point here is not to propose a new method to prepare this liposome vaccine. The central idea is to give new dresses for old vaccines by using classical and well established liposome preparation method changing only the encapsulation pH and the immunization  protocol.

Mice were primed with liposome formulations containing Dtxd prepared in pH 4.0 or 7.0 or 9.0. The IgM produced by immediate response of all liposome formulations were higher than the control (free protein). The response patterns and the immune maturity were measured by IgG1 and IgG2a titrations. It is known that the IgGs are produced in the following order: IgG1 > IgG3 > IgG2a. The neutralizing antibodies are mainly due to IgG1 (more abundant) but the IgG2a is more specific and is related to the immunological maturation degree. The IgG1 titles produced by both formulations at pH 4.0 and 7.0 were at least 22 higher than those produced by mice injected liposome formulation at pH 9.0. When the booster were done 138 days after priming the mice produced a IgG2a  title of 29 and the group that received the booster 30 days after priming produced a title of 25. The strongest antibody production was the neutralizing antibody produced by those mice injected with liposome formulation at pH 4.0 with the booster done 138 days after priming. The simple change on liposome pH formulation and timing of the booster enhanced both, antibody production and selectivity.

Grants: CNPq (477154/2003-4 and 474781/01-1), FAPESP (2000/14228-3 02/07293-9 and 94/5854-5).  VA Silva is a fellowship from CAPES.