Navegando por Palavras-chave "Vaccines, DNA"

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    Efeito de citocinas e toxina tetânica na vacinação gênica de tumores que expressam CEA com Scfv6C4
    (Universidade Federal de São Paulo (UNIFESP), 2017-03-29) Zanetti, Bianca Ferrarini [UNIFESP]; Han, Sang Won [UNIFESP]; http://lattes.cnpq.br/0069955147703693; http://lattes.cnpq.br/3688249051412919; Universidade Federal de São Paulo (UNIFESP)
    Introduction: Colon and rectum cancers are highly prevalent among men and women, and prevention and treatment are major medical and scientific challenges. Carcinoembryonic antigen (CEA) is the main tumor associated antigen of these cancers. Previously, our group developed a DNA vaccine against CEA-expressing tumors using a CEA surrogate, scFv6.C4, and its efficacy, evaluated in transgenic mice for CEA, showed 40% tumor-free animais by more than 100 days and in the others the survival increase was between 30 and 70% in relation to the non-vaccinated group. Objective: To evaluate the adjuvant effect of IFNy (Interferon Gamma), GM-CSF (Granulocyte Macrophage Colony-Stimulating Factor), FrC (Fragment C of Tetanus Toxin) and IDUA (Alpha-L-Iduronidase) in gene vaccination with scFv6.C4. Methods: C57BU6J-CEA2682 mice were immunized 4 times by intramuscular electroporation with the plasmid uP-PS/scFv6.C4 alone, or in combination with adjuvant vectors expressing FrC, GM-CSF, IFNy or IDUA. Vaccinated animais were challenged by subcutaneous injection of murine colon adenocarcinoma cells, MC38-CEA, and tumor growth was monitored. The humoral andcellular immune responses were accessed by ELlSA, immunocytochemistry, ELlSPOT, cell proliferation and cYt~toxicity assays. Results: Immunization with scFv6.C4 induced anti-CEA antibodies, with titre about 4- fold higher than preimmune serum. When challenged with MC38-CEA cells, approximately half of the immunized animais did not develop tumor during 80 days of observation, and the others had varying degrees of retardation in tumor growth. The adjuvants tested did not lead to a significant increase in antibody titer, however, animais immunized with scFv6.C4 and FrC or IFNy had increased survival. Cellular response assays showed a significant increase in cytotoxic cell response, especially in the animais vaccinated with FrC. Conclusions: Immunization with scFv6.C4 in combination with adjuvants FrC or IFNy elevated antitumor effect via increased cytotoxic cell response.
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    Estudo comparativo de protocolos de imunização gênica: eletroporação aumenta consistentemente a resposta imune humoral
    (Universidade Federal de São Paulo (UNIFESP), 2008-03-26) Parise, Carolina Bellini [UNIFESP]; Han, Sang Won [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Gene immunization may bypass some difficulties found with protein immunogen, such as the obtainment of purified antigen and the immune response reactivity to its native conformation. Thus, antigen encoding DNA inserted into a vector is inoculated into animal and the protein expressed in vivo with the appropriate three-dimensional structure stimulates the production of specific antibodies. However, the gene immunization methods may determine the efficacy of DNA vaccine. The present study compared four protocols of DNA immunization, using three different antigens: two of them phylogenetically conservative, human vascular endothelial growth factor 165 (hVEGF165) and human fibroblast growth factor-2 (hFGF-2), and other from vegetal origin, Kunitz-type serine protease inhibitor from Bauhinia bauhinioides (BbKi). For this, Balb/c mice were immunized with plasmid DNA encoding hVEGF165, hFGF-2 or BbKi genes. In the first protocol, animals were immunized by intrasplenic (i.s.) pathway; in the second, intramuscularly (i.m.); in the third, i.m. injections were followed by electroporation (ep); and in the fourth, i.m. injections followed by ep were performed in animals pre-immunized with antigen-transfected cells. Sera were analyzed by ELISA to detect the presence of anti-hVEGF165, -hFGF-2 or -BbKi antibodies. Results showed that i.s. immunization did not elicit detectable humoral immune response in our conditions. On the other hand, statistical analyses revealed that the ep improved the immune response to i.m. immunization and that three DNA immunizations followed by ep elicited the same effect obtained by two i.m. immunizations followed by ep in pre-immunized animals with antigentransfected cells. Our results showed that all protocols worked similarly for the three studied antigens and that i.m. gene immunization followed by ep was the more advantageous protocol. In addition, the immune response to i.m. immunization followed by ep was comparable to that obtained by protein immunization. Finally, these data allowed us select an efficient DNA immunization protocol that makes possible the antibody obtainment in the lack of purified protein.