title: Retargeting of adenovirus vectors through genetic fusion of a single-chain or single-domain antibody to capsid protein IX.
abstract: Adenovirus (Ad) vectors are the most commonly used system for gene therapy applications, due in part to their ability to infect a wide array of cell types and tissues. However, many therapies would benefit from the ability to target the Ad vector only to specific cells, such as tumor cells for cancer gene therapy. In this study, we investigated the utility of capsid protein IX (pIX) as a platform for the presentation of single-chain variable-fragment antibodies (scFv) and single-domain antibodies (sdAb) for virus retargeting. We show that scFv can be displayed on the capsid through genetic fusion to native pIX but that these molecules fail to retarget the virus, due to improper folding of the scFv. Redirecting expression of the fusion protein to the endoplasmic reticulum (ER) results in correct folding of the scFv and allows it to recognize its epitope; however, ER-targeted pIX-scFv was incorporated into the Ad capsid at a very low level which was not sufficient to retarget virus infection. In contrast, a pIX-sdAb construct was efficiently incorporated into the Ad capsid and enhanced virus infection of cells expressing the targeted receptor. Taken together, our data indicate that pIX is an effective platform for presentation of large targeting polypeptides on the surface of the virus capsid, but the nature of the ligand can significantly affect its association with virions.
authors.affiliation: Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Kathy L
authors.initials: KL
authors.lastname: Poulin
authors.forename: Robert M
authors.initials: RM
authors.lastname: Lanthier
authors.forename: Adam C
authors.initials: AC
authors.lastname: Smith
authors.forename: Carin
authors.initials: C
authors.lastname: Christou
authors.forename: Milagros
authors.initials: M
authors.lastname: Risco Quiroz
authors.forename: Karen L
authors.initials: KL
authors.lastname: Powell
authors.forename: Ryan W
authors.initials: RW
authors.lastname: O'Meara
authors.forename: Rashmi
authors.initials: R
authors.lastname: Kothary
authors.forename: Ian A
authors.initials: IA
authors.lastname: Lorimer
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Parks
mesh_terms: D000256:Adenoviridae / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000235:genetics; D001483:Base Sequence; D016466:CHO Cells; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000939:Epitopes / Q000378:metabolism; D066246:ErbB Receptors / Q000276:immunology / Q000378:metabolism; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D006801:Humans; D010957:Plasmids / Q000235:genetics; D015202:Protein Engineering; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D000906:Antibodies; D036022:Capsid Proteins; D000939:Epitopes; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; C410723:epidermal growth factor receptor VIII; D066246:ErbB Receptors