Refinement and assessment of a novel adenovirus targeting platform for gene therapy applications

Intravascular delivery of adenovirus vectors is the most viable route of administration for a broad range of gene therapy clinical applications. Much work has focused on targeting the virus to selected cell types for improved gene delivery and to avoid gene transfer in non-target cells. However upon contact with the bloodstream a multitude of Ad interactions with host factors impact on the tropism, immunology and toxicity of the virus. Designing vectors which can bypass the native Ad infectivity pathways in order to retarget the vector to specific cells/tissues is of great importance.

Recent studies have shown that upon contact with the blood Ad5 binds to coagulation factor X (FX), which then mediates substantial liver transduction. A great deal of effort has been focused on understanding and manipulating the Ad:FX interaction in order to block FX-mediated hepatic sequestration.  Ad5 vectors with point mutations in the hexon protein have been developed, which block virus binding to FX and hence show diminished liver transduction. FX-binding ablated vectors, coupled with mutation of the integrin interacting RGD motif in the penton base have resulted in decreased liver and splenic uptake, along with a decreased antiviral inflammatory response. The current project is focused on developing and characterising vectors devoid of interactions with the native receptors – CAR, integrins and FX. Designing vectors which bypass the natural tropism should allow for more effective targeting strategies and this will be investigated by incorporating targeting peptides into the HI loop of the novel vector.

Publications

1. Bradshaw AC, Coughlan L, Miller AM, Alba R, van Rooijen N, Nicklin SA, Baker AH. Biodistribution and inflammatory profiles of novel penton and hexon double-mutant serotype 5 adenoviruses. J Control Release. 2012;164:394-402.
2. Alba R, Bradshaw AC, Coughlan L, Denby L, McDonald RA, Waddington SN, Buckley SM, Greig JA, Parker AL, Miller AM, Wang H, Lieber A, van Rooijen N,McVey JH, Nicklin SA, Baker AH. Biodistribution and retargeting of FX-binding ablated adenovirus serotype 5 vectors. Blood. 2010;116:2656-64.
3. Alba R, Bradshaw AC, Parker AL, Bhella D, Waddington SN, Nicklin SA, van Rooijen N, Custers J, Goudsmit J, Barouch DH, McVey JH, Baker AH. Identification of coagulation factor (F)X binding sites on the adenovirus serotype 5 hexon: effect of mutagenesis on FX interactions and gene transfer. Blood. 2009;114:965-71.