Deletion of immunomodulatory A44L, A46R and C12L viral genes from Modified Vaccinia Ankara (MVA) genome: effect on its immunogenicity

HOLGADO, M.P.; MAETO, C.; FALIVENE, J.; GHIGLIONE, Y. ; DEL MEDICO ZAJAC, M.P.; CALAMANTE, G.; GHERARDI, M.M

Ciudad del Cabo

Conferencia; HIV Research for Prevention (HIV R4P); 2014

Background: (491) MVA still retains genes involved in host immune response evasion. We have previously reported the optimization of its vaccine potential after removing the C12L gene, coding an IL18 binding protein. Here we analyze the immunogenicity of MVA vectors harboring the simultaneous deletion of two viral genes: A44L, implicated in synthesis of steroid hormones and A46R, which inhibits transduction signals from TLR (MVAΔA44L-A46R: MVAd); or including C12L deletion also (MVAΔC12L/ΔA44L-A46R: MVAt) Methods: (579) C57Bl/6 mice were immunized with MVAwt or deleted MVAs (ΔMVAs). We evaluated the adaptive T-cell response to VV (Vaccinia Virus) epitopes at acute (7dpi) and memory phases (45dpi) in spleen and draining lymph nodes (DLNs). The amount of IFNγ and IL2 producing cells was measured by ELISPOT. We studied the percentage of specific cytotoxic CD8 T-cells by flow cytometry, and the response of memory T-cells among specific proliferating CD8 T-cells. To study the innate response, we immunized mice with MVAwt or MVAt and pattern of cytokines produced were evaluated between 0-24 hpi Results: (708) At 7dpi both ΔMVAs induced significant increases in IFNγ anti-VV CD8 and CD4-T cells vs MVAwt (1.5 to two-fold,p