152. Coxsackievirus-Adenovirus Receptor (CAR) and αvβ3 or αvβ5 Integrin Independent Internalization of Porcine Adenoviral Vectors: Implications in Gene Therapy

Abstract

Nonhuman adenoviruses including porcine adenovirus serotype 3 (PAd3) are emerging vectors for gene delivery. PAd3 efficiently transduces human and murine cells and circumvents preexisting humoral immunity in humans. Coxsackievirus and adenovirus receptor (CAR) is the primary receptor and |[alpha]|v|[beta]|3 or |[alpha]|v|[beta]|5 integrin is involved as a secondary receptor for various human adenovirus (HAd) subtypes including HAd5. In this study we deduced the role of CAR, |[alpha]|v|[beta]|3 or |[alpha]|v|[beta]|5 integrin in PAd3 internalization. Transduction experiments were conducted in human mammary epithelial (MCF-10A) cells using replication defective PAd-GFP (PAd3 vector expressing green fluorescent protein [GFP]) and HAd-GFP (HAd5 vector expressing GFP). MCF-10A cells were treated with or without anti-human CAR, or anti-|[alpha]|v|[beta]|3 or anti-|[alpha]|v|[beta]|5 integrin antibodies prior to infection with HAd-GFP or PAd-GFP. Significant (P<0.05) inhibition in transduction by HAd-GFP was observed in the antibody treated cells as compared to the untreated cells, whereas transduction by PAd-GFP remained to similar levels irrespective of the treatment. To study fiber knob-mediated virus interference, MCF-10A cells were treated with or without the recombinant HAd5 or PAd3 knob followed by infection with HAd-GFP or PAd-GFP. Significant (P<0.05) inhibition was observed only in transduction of the homologous vector. These results suggested that PAd3 internalization was CAR- as well as |[alpha]|v|[beta]|3 or |[alpha]|v|[beta]|5 integrin-independent and the primary receptor for HAd5 and PAd3 were distinct. CAR- and |[alpha]|v|[beta]|3 or |[alpha]|v|[beta]|5 integrin-independent entry of PAd3 vectors may have implications in targeting cell types that are not efficiently transduced by other adenoviral vectors.