Assessment of baculoviral vs. adenoviral vectors for gene delivery in experimental brain cancer

PIDRE ML; NICOLA CANDIA AJ; ROMANOWSKI V; CANDOLFI M; ASAD AS; FALLIT MG; IMSEN M; ZANETTI FA; SAGRIPANTI S; ZUCCATO CF; SEILICOVICH A

Mar del Plata

Congreso; Reunión anual Sociedad Argentina de Investigación Clínica (SAIC) 2019; 2019

We aimed to compare the transduction efficiency and neuropathology of adenoviral (AdV) vs baculoviral (BV) vectors in order to develop therapeutic strategies for the treatment of brain cancer. Although AdVs can be produced in high titers and yield good transduction efficiency in the brain, the population exhibits pre-existing anti-AdV immunity, leading to transient transgene expression. BVs primarily infect insects at larval stage, but they also transduce cells from other species. Even though BVs are less stable than AdVs after long-term storage, their advantage is that pre-existing immunity against BVs has not been reported in humans. Our general hypothesis is that BVs may lead to more stable transgene expression than AdVs upon injection into naïve and neoplastic brain. We constructed AdV and BV encoding tdTomato under the control of the CMV promoter. Human and rat GB cell lines were incubated with different doses of AdV or BV for 48 h and transduction efficiency was assessed by microscopy. AdV (MOI 50-500) and BV (MOI 500-2000) transduced GB cell lines with similar efficiency. AdV (~107 UFP) and BV (~106 UFP) were injected by stereotactic surgery into orthotopic GL26 GB growing in the brain of C57Bl/6 mice and 5 d later, mice were perfused/fixed and brains were sectioned in cryostat. We detected comparable expression of tdTomato within tumors injected with either vector. AdV or BV were also injected into the striatum of naïve mice and 5 d later, brains were processed for immunohistochemistry to identify glial cells, showing that transduced brain cells were GFAP+. CD45 staining showed similar immune cell infiltration around BV and AdV injection sites and no signs of neurotoxicity were observed. Our findings indicate that both vectors transduce GB and glial cells with similar efficiency without evident neurotoxicity. Given that humans do not present pre-existing immunity against BVs, BV may constitute a valuable tool for delivery of therapeutic genes in the brain.