Navegando por Autor "Abrantes, Christiane de Freitas"

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    Antibody responses induced by Leish-Tec®, an A2-basedvaccine for visceral leishmaniasis, in a heterogeneous caninepopulation.
    (2014) Testasicca, Miriam Conceição de Souza; Santos, Mariana Silva dos; Machado, Leopoldo Marques; Serufo, Ângela Vieira; Doro, Daniel; Avelar, Daniel Moreira de; Tibúrcio, Ana Maria Leonardi; Abrantes, Christiane de Freitas; Coelho, George Luiz Lins Machado; Grimaldi Junior, Gabriel; Gazzinelli, Ricardo Tostes; Fernandes, Ana Paula Salles Moura
    Zoonotic visceral leishmaniasis (VL) is a widespread disease, and dogs are the main reser-voirs for human parasite transmission. Hence, development of an effective vaccine thatprevents disease and reduces the transmission of VL is required. As euthanasia of seropos-itive dogs is recommended in Brazil for VL epidemiological control, to include anti-VLcanine vaccines as a mass control measure it is necessary to characterize the humoralresponses induced by vaccination and if they interfere with the reactivity of vaccinateddogs in serological diagnostic tests. Leish-Tec®is an amastigote-specific A2 recombinantprotein vaccine against canine visceral leishmaniasis (CVL) that is commercially availablein Brazil. Here, we tested the immunogenicity of Leish-Tec®in a heterogeneous dog popula-tion by measuring A2-specific antibody responses. Healthy dogs (n = 140) of various breedswere allocated to two groups: one group received Leish-Tec®(n = 70), and the other groupreceived a placebo (n = 70). Anti-A2 or anti-Leishmania promastigote antigen (LPA) antibodylevels were measured by ELISA in serum samples collected before and after vaccination.An immunochromatographic test (DPP) based on the recombinant K28 antigen was alsoused for serodiagnosis of CVL. Vaccinated animals, except one, remained seronegative foranti-LPA total IgG and anti-K28 antibodies. Conversely, seropositivity for anti-A2 total IgGantibodies was found in 98% of animals after vaccination. This value decreased to 81.13% at6 months before rising again (98%), after the vaccination boost. Anti-A2 IgG2 and IgG1 titers.
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    Epitope mapping and protective immunity elicited by adenovirus expressing the Leishmania amastigote specific A2 antigen : correlation with IFN- and cytolytic activity by CD8+ T cells.
    (2008) Resende, Daniela de Melo; Caetano, Bráulia Costa; Dutra, Míriam Santos; Abrantes, Christiane de Freitas; Verly, Rodrigo Moreira; Resende, Jarbas Magalhães; Veloso, Dorila Piló; Rezende, Simone Aparecida; Romero, Oscar Bruna; Fernandes, Ana Paula Salles Moura; Gazzinelli, Ricardo Tostes
    A2was identified as an amastigote virulence factor of Leishmania (Leishmania) donovani and as a candidate antigen for vaccine development against visceral leishmaniasis. Here, predicted hydrophilic, class I and II MHC-binding synthetic peptides were used to define epitopes recognized by A2-specific antibodies, CD8+ T and CD4+ T cells, respectively. Immunization of BALB/c mice with adenovirus expressing A2 (AdA2) resulted in lowantibody response, contrasting with high levels of IFN-_ producing CD4+ T and CD8+ T cells specific for A2. Further, A2-specific CD8+ T cells from immunized mice were capable of lysing sensitized target cells in vivo. Finally, we demonstrated an association of A2-specific T cell responses and reduced parasitism in both liver and spleen from mice immunized with AdA2 and challenged with L. (L.) chagasi.