Browsing by Author "Vianna, Leonardo Rocha"

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    Clinical value of anti-Leishmania (Leishmania) chagasi IgG titers detected by flow cytometry to distinguish infected from vaccinated dogs.
    (2007) Andrade, Renata Aline de; Reis, Alexandre Barbosa; Gontijo, Célia Maria Ferreira; Braga, Lidiane Bento; Rocha, Roberta Dias Rodrigues; Araújo, Márcio Sobreira Silva; Vianna, Leonardo Rocha; Martins Filho, Olindo Assis
    Leishmune® vaccination covers a broader number of endemic areas of canine visceral leishmaniasis (CVL) and therefore the development of new serological devices able to discriminate CVL from Leishmune® vaccinees becomes an urgent need considering the post-vaccine seroconversion detected throughout conventional methodologies. Herein, we have described the establishment of a flow cytometry based methodology to detect anti-fixedL. ( L. ) chagasipromastigotes antibodies (FC-AFPA-IgG, FC-AFPA-IgG1 and FC-AFPA-IgG2) in sera samples from Leishmania ( Leishmania ) chagasiinfected dogs and Leishmune® vaccinees. The results of FC-AFPA were reported along the sera titration curve (1:128–1:524,288), as percentage-of-positive-fluorescent-parasite (PPFP). The use of PPFP = 20% as a cut-off edge to segregate negative and positive results at sera dilution 1:2048 revealed outstanding performance indexes that elect FC-AFPA-IgG and IgG2 (both detected by polyclonal FITC-labeled second step reagent) applicable to the serological diagnosis of CVL, with 100% of specificity for both IgG and IgG2 and 97 and 93% of sensitivity, respectively. Moreover, FC-AFPA-IgG, applied at sera dilution 1:2048, also appeared as a useful tool to discriminate L. chagasiinfected dogs from Leishmune® vaccinees, with 76% of specificity. Outstanding likelihood indexes further support the performance of FC-AFPA-IgG for exclusion diagnosis of CVL in Leishmune® vaccinees. Analysis of FC-AFPA-IgG at sera dilution 1:8192 revealed the most outstanding indexes, demonstrating that besides the ability of PPFP 20% to exclude the diagnosis of CVL, a PPFP values higher 80%, mostly observed for infected dogs (INF) have a minimal change to come from a non-infected animal (NI) or Leishmune®.
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    Despite Leishvaccine and Leishmune ® trigger distinct immune profiles, their ability to activate phagocytes and CD8 + T-cells support their high-quality immunogenic potential against canine visceral leishmaniasis.
    (2008) Araújo, Márcio Sobreira Silva; Andrade, Renata Aline de; Vianna, Leonardo Rocha; Mayrink, Wilson; Reis, Alexandre Barbosa; Avelar, Renato Sathler; Carvalho, Andréa Teixeira de; Andrade, Mariléia Chaves; Melo, Maria Norma; Martins Filho, Olindo Assis
    Phenotypic features of peripheral blood leukocytes have been investigated as a prerequisite to characterize the protective immunity attributed to both Leishvaccine and Leishmune ® . Our results showed that either those vaccine were accompanied by distinct profiles on innate immune compartment. While Leishvaccine promoted early changes in phenotypic fea-tures of neutrophils and eosinophils with late involvement of monocytes, Leishmune ® induced early and persistent activation of neutrophils and monocytes, without changes on eosinophil activation status. Regarding the adaptive immunity, Leishvaccine sponsored a mixed profile, associated with phenotypic changes of T and B-lymphocytes. Major phenotypic changes in CD4 + T-cells with transient activation of CD8 + T-cell, besides decreased frequency of B-cell expressing
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    Immunological changes in canine peripheral blood leukocytes triggered by immunization with first or second generation vaccines against canine visceral leishmaniasis.
    (2011) Araújo, Márcio Sobreira Silva; Andrade, Renata Aline de; Avelar, Renato Sathler; Magalhães, Camila Paula; Carvalho, Andréa Teixeira de; Andrade, Mariléia Chaves; Campolina, Sabrina Sidney; Melo, Maria Norma; Vianna, Leonardo Rocha; Mayrink, Wilson; Reis, Alexandre Barbosa; Malaquias, Luiz Cosme Cotta; Rocha, Luciana Morais; Martins Filho, Olindo Assis
    In this study, we summarized the major phenotypic/functional aspects of circulating leuko-cytes following canine immunization with Leishvaccine and Leishmune ®. Our findings showed that Leishvaccine triggered early changes in the innate immunity (neutrophils and eosinophils) with late alterations on monocytes. Conversely, Leishmune ® induced early phenotypic changes in both, neutrophils and monocytes. Moreover, Leishvaccine triggered mixed activation-related phenotypic changes on T-cells (CD4 + and CD8 +) and B-lymphocytes, hereas Leishmune® promoted a selective response, mainly associated with CD8 + T-cell activation. Mixed cytokine profile (IFN- /IL-4) was observed in Leishvaccine immunized dogs whereas a selective pro-inflammatory pattern (IFN- /NO) was induced by Leishmune ® vaccination. The distinct immunological profile triggered by Leishvaccine and Leishmune ® may be a direct consequence of the distinct biochemical composition of these immunobiological, i.e. complex versus purified Leishmaniaantigen along with Bacillus Calmette-Guérin (BCG) versus saponin adjuvant. Both immunobiologicals are able to acti-vate phagocytes and CD8 + T-cells and therefore could be considered as a putative vaccines against canine visceral leishmaniasis (CVL)
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    T-cell-derived cytokines, nitric oxide production by peripheral blood monocytes and seric anti- Leishmania (Leishmania) chagasi IgG subclass patterns following immunization against canine visceral leishmaniasis using Leishvaccine and Leishmune ®.
    (2009) Araújo, Márcio Sobreira Silva; Andrade, Renata Aline de; Avelar, Renato Sathler; Carvalho, Andréa Teixeira de; Andrade, Mariléia Chaves; Vianna, Leonardo Rocha; Mayrink, Wilson; Reis, Alexandre Barbosa; Malaquias, Luiz Cosme Cotta; Melo, Maria Norma; Martins Filho, Olindo Assis
    It is generally accepted that distinct cytokine expression by the cellular immune response plays a critica role during the outcome of experimental as well as natural canine visceral Leishmaniasis (CVL). Despite the fact that immunoprophylaxis of CVL has become an important control strategy and protective immunity has been reported upon immunization with whole as well as purifiedLeishmaniaantigens, the cytokine profile of T-cells triggered by anti-CVL vaccines still remain to be determined. Herein, we have developed a cross-sectional analysis of German Shepherd dogs submitted to vaccination protocols with Leishvaccine (n = 6) and Leishmune ® (n = 6). Our data identified distinct immunological profiles elicited by Leishvaccine and Leishmune ® , with the Leishvaccine triggering a mixed, IFN- and IL-4, cytokine pattern in addition to high levels of anti- LeishmaniaIgG1, whereas the Leishmune ® induced an immunological pattern char- acterized by enhanced levels of IFN- , NO and anti- Leishmania chagasi IgG2. It was important to notice that despite the distinct immunological patterns triggered by Leishvaccine and Leishmune ® , the ability of both immunobiologicals to activate T-cell-derived IFN- synthesis further suggesting their immunogenic potential against CVL. These findings added support to our hypothesis that both antigenic composition (whole antigen in Leishvaccine versus purified antigen in Leishmune ® ) as well as the adjuvant nature (BGC and saponin) used for the vaccine formulation may count for the distinct activation pattern observed.