Navegando por Autor "Ferreira, Sidney de Almeida"
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Item In vitro infectivity of strains isolated from dogs naturally infected with Leishmania infantum present a distinct pathogenic profile in hamsters.(2020) Resende, Lucilene Aparecida; Soares, Rodrigo Dian de Oliveira Aguiar; Moreira, Nádia das Dores; Ferreira, Sidney de Almeida; Lanna, Mariana Ferreira; Cardoso, Jamille Mirelle de Oliveira; Mathias, Fernando Augusto Siqueira; Vital, Wendel Coura; Mariano, Reysla Maria da Silveira; Leite, Jaqueline Costa; Silveira, Patricia; Carvalho, Tatiane Furtado de; Santos, Renato Lima; Lemos, Denise da Silveira; Martins Filho, Olindo Assis; Dutra, Walderez Ornelas; Reis, Alexandre Barbosa; Giunchetti, Rodolfo CordeiroVisceral leishmaniasis (VL) is a severe disease caused by Leishmania infantum. Dogs are the parasite’s main reservoir, favoring its transmission in the urban environment. The analysis of L. infantum from infected dogs contributes to the identification of more virulent parasites, thereby supporting basic and applied studies such as vaccinal and therapeutic strategies. We proposed the in vitro and in vivo characterization of L. infantum strains from naturally infected dogs from a VL endemic area based on an infectivity and pathogenicity analysis. DH82 canine macrophages were infected in vitro with different strains for infectivity analysis, showing distinct infectivity profiles. The strains that showed greater and lesser infectivity using in vitro analyses (616 and 614, respectively) were used to infect hamsters for pathogenicity analysis. The group infected with strain 616 showed 100% survival while the group infected with strain 614 showed 50% after seven months of follow up. Furthermore, the 614 strain induced more noticeable clinicopathological changes and biochemical abnormalities in liver function, along with high inflammation and parasite load in the liver and spleen. We confirmed high variability of infectivity and pathogenicity in L. infantum strains from infected dogs. The results support the belief that screening for L. infantum infectivity using in vitro experiments is inadequate when it comes to selecting the most pathogenic strain.Item A vaccine therapy for canine visceral leishmaniasis promoted significant improvement of clinical and immune status with reduction in parasite burden.(2017) Roatt, Bruno Mendes; Soares, Rodrigo Dian de Oliveira Aguiar; Reis, Levi Eduardo Soares; Cardoso, Jamille Mirelle de Oliveira; Mathias, Fernando Augusto Siqueira; Brito, Rory Cristiane Fortes de; Silva, Sydnei Magno da; Gontijo, Nelder de Figueiredo; Ferreira, Sidney de Almeida; Valenzuela, Jesus G.; Oliveira, Rodrigo Corrêa de; Giunchetti, Rodolfo Cordeiro; Reis, Alexandre BarbosaHerein, we evaluated the treatment strategy employing a therapeutic heterologous vaccine composed of antigens of Leishmania braziliensis associated with MPL adjuvant (LBMPL vaccine) for visceral leishmaniasis (VL) in symptomatic dogs naturally infected by Leishmania infantum. Sixteen dogs received immunotherapy with MPL adjuvant (n = 6) or with a vaccine composed of antigens of L. braziliensis associated with MPL (LBMPL vaccine therapy, n = 10). Dogs were submitted to an immunotherapeutic scheme consisting of 3 series composed of 10 subcutaneous doses with 10-day interval between each series. The animals were evaluated before (T0) and 90 days after treatment (T90) for their biochemical/hematological, immunological, clinical, and parasitological variables. Our major results showed that the vaccine therapy with LBMPL was able to restore and normalize main biochemical (urea, AST, ALP, and bilirubin) and hematological (erythrocytes, hemoglobin, hematocrit, and platelets) parameters. In addition, in an ex vivo analysis using flow cytometry, dogs treated with LBMPL vaccine showed increased CD3+ T lymphocytes and their subpopulations (TCD4+ and TCD8+), reduction of CD21+ B lymphocytes, increased NK cells (CD5−CD16+) and CD14+ monocytes. Under in vitro conditions, the animals developed a strong antigen- specific lymphoproliferation mainly by TCD4+ and TCD8+ cells; increasing in both TCD4+IFN-γ+ and TCD8+IFN-γ+ as well as reduction of TCD4+IL-4+ and TCD8+IL-4+ lymphocytes with an increased production of TNF-α and reduced levels of IL-10. Concerning the clinical signs of canine visceral leishmaniasis, the animals showed an important reduction in the number and intensity of the disease signs; increase body weight as well as reduction of splenomegaly. In addition, the LBMPL immunotherapy also promoted a reduction in parasite burden assessed by real-time PCR. In the bone marrow, we observed seven times less parasites in LBMPL animals compared with MPL group. The skin tissue showed a reduction in parasite burden in LBMPL dogs 127.5 times higher than MPL. As expected, with skin parasite reduction promoted by immunotherapy, we observed a blocking transmission to sand flies in LBMPL dogs with only three positive dogs after xenodiagnosis. The results obtained in this study highlighted the strong potential for the use of this heterologous vaccine therapy as an important strategy for VL treatment.