AVALIAÇÃO DA RESPOSTA IMUNE A VACINAS DE ANTÍGENO PARTICULADO DE Leishmania sp E SUA ASSOCIAÇÃO COM VACINA DE DNA pCI-neo-p36(LACK) EM CAMUNDONGOS BALB/c DESAFIADOS COM Leishmania chagasi

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

American visceral leishmaniasis is a chronic disease that can reach 98% of human mortality when not treated. Due to its severity and high incidence, vaccination has become an important approach to protection. Several vaccines have been tested, amongst then, freeze-thawed antigen and DNA vaccines. These two vaccines have demonstrated the capacity to reduce the parasite burden in liver and spleen in murine model and to induce the production of IFN-, with the induction of a long-term cellular immunity in some cases. In our study, BALB/c mice were vaccinated with a three doses subcutaneous vaccine containing 100 μg of L. chagasi, L. braziliensis or L. amazonensis freeze-thawed antigen with 50 μg of saponin as an adjuvant, associated or not with an intramuscular one, in two doses, with 100 μg of pCI-neo-p36(LACK). This DNA vaccine was constituted of LACK (Leishmania homologue of receptors for activated C kinase) expression gene, a 36 kDa protein highly conserved in all species and life cycle stages of Leishmania. In the two vaccines protocols, mice were challenged intravenously with 1 x 107 L. chagasi promastigotes 4 or 12 weeks after booster and sacrified 5 weeks after challenge for the analysis of the vaccines protective capacity in liver and spleen and the measure of the production of IFN-g and IL-4 by splenocytes. Data showed that the pCI-neo-p36(LACK) associated to L. chagasi freeze-thawed antigen induced a higher protection than the freeze-thawed antigen alone, specially in liver when the challenge was performed 4 weeks after booster. In addiction, L. amazonensis vaccine induced a greater reduction in parasite burden than L. braziliensis. The vaccines induced a significant production of IFN-g but not of IL-4, that was suppressed is some cases. Despite the showed capability of the vaccines association in increase the protection against the parasite, problems with the use of DNA vaccines must be reviewed.

ASSUNTO(S)

1. leishmaniose - teses. 2. vacinas -teses. 3. saponinas - teses. 4. antígenos - teses. imunologia

ACESSO AO ARTIGO

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