Detalhes bibliográficos
| Ano de defesa: |
2009 |
| Autor(a) principal: |
Pinheiro, Paulo Henrique da Costa [UNIFESP] |
| Orientador(a): |
Não Informado pela instituição |
| Banca de defesa: |
Não Informado pela instituição |
| Tipo de documento: |
Tese
|
| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de São Paulo (UNIFESP)
|
| Programa de Pós-Graduação: |
Não Informado pela instituição
|
| Departamento: |
Não Informado pela instituição
|
| País: |
Não Informado pela instituição
|
| Palavras-chave em Português: |
|
| Link de acesso: |
http://repositorio.unifesp.br/handle/11600/8809
|
Resumo: |
A recombinant protein, rLdccys1, produced by expression of the gene encoding a 30 kDa cysteine proteinase from Leishmania (Leishmania) chagasi, was used to detect specific antibodies in serum by enzyme-linked immunosorbent assays and to test for reactivity in delayed-type hipersensitivity (DTH) responses of dogs from an endemic region of visceral leishmaniasis (VL), Teresina, Piauí State, Brazil. The recombinant protein was also used for immunization of dogs and evaluation of its possible protective role against L. (L.) chagasi infection. The sensitivity for detection of specific antibodies to L. (L.) chagasi using rLdccys1 and lysates from L. (L.) chagasi promastigotes and amastigotes was 96%, 68%, and 69%, respectively. No cross reactivity between rLdccys1 and Chagas disease was observed, and little reactivity was found with sera from dogs with babesiosis and ehrlichiosis. The specificity of ELISA assays using rLdccys1, lysates from L. (L.) chagasi promastigotes and amastigotes was 96%, 69%, and 68%, respectively. DTH responses were determined after subcutaneous injection of rLdccys1 or L. (L.) chagasi amastigote extract and the induration area was measured at 24, 48 and 72 h after injection. All asymptomatic dogs showed a positive intradermal response to rLdccys1 (10 mm) which peaked at 48 h, whereas no significant reactivity to the recombinant antigen was found in the symptomatic group. DTH responses to rLdccys1 were higher than those induced by amastigote extract. Histological analysis of the intradermal induration showed a predominance of necrotic and hemorrhagic areas in sections from asymptomatic dogs injected with L. (L.) chagasi amastigote extract, whereas a typical granulomatous reaction mediated by mononuclear cells was observed in sections from asymptomatic animals injected with rLdccys1. Data analysis from ELISA and DTH assays with rLdccys1 and L. (L.) chagasi amastigote extracts showed that humoral and cellular responses were inversely correlated during the development of canine VL. Cellular immune responses induced by the recombinant antigen were evaluated after immunization of dogs with rLdccys1 plus Propionibacterium acnes. Peripheral blood mononuclear cells isolated from rLdccys1-immunized dogs showed significant stimulation indexes after in vitro incubation with either rLdccy1 or L. (L.) chagasi amastigote extracts. Cytokine dosages in the supernatants from lymphocyte cultures showed significant levels of IFN-γ, whereas IL-10 was not detected. Whereas 3 from 4 dogs immunized with rLdccys1 plus P. acnes and challenged by intraperitoneal injection of 1x104 L. (L.) chagasi amastigotes survived ten weeks after challenge, control dogs which received either PBS or P. acnes died after four and six weeks, respectively. The load of L. (L.) chagasi amastigotes in spleen, liver, and bone marrow from rLdccys1-immunized dogs was significantly reduced in comparison to that of non immunized controls. A significant concentration of IFN-γ and basal levels of IL-10 were detected in sera from dogs immunized with rLdccys1. All dogs immunized with rLdccys1 plus P. acnes and challenged by the bite of L. (L.) chagas infected Lutzomyia longipalpis survived until sixteen weeks after challenge, whereas control dogs injected with PBS or P. acnes died after seven and nine weeks, respectively. Control dogs showed a significant number of L. (L.) chagasi amastigotes in liver and spleen, but no parasites were found in rLdccys1- immunized dogs. During immunization with rLdccys1 there was an increase of serum levels of IFN-γ in the immunized dogs that peaked one week after challenge. In contrast, a very low concentration of IL-10 was detected in these animals. Overall, these findings indicate that L. (L.) chagasi recombinant cysteine proteinase is potentially useful for diagnosis and immunoprophylaxis of canine VL. We believe that results obtained open perspectives for immunization of dogs in the field and evaluation of the impact on the disease incidence. |
