Persistent and Secondary Adenovirus-Mediated Hepatic Gene Expression Using Adenovirus Vector Containing CTLA4IgG

Abstract

Adenovirus vectors can transfer recombinant genes efficiently into a wide variety of cells in vivo, but have serious limitations: gene expression is transient and secondary gene transfer is inefficient or impossible because of cellular and humoral immune responses against adenovirus-transduced cells. To solve these limitations, we have constructed an adenovirus vector, Adex1CACTLA4IgG, that expresses CTLA4IgG molecules. After in vivo administration of Adex1CACTLA4IgG (9.0 × 10⁹ PFU), the peak level of serum CTLA4IgG was 29.8 mg/ml on day 4. The serum CTLA4IgG concentration gradually fell but was still 5.7 mg/ml on day 90. However, the serum concentration of CTLA4IgG was elevated after a second administration of Adex1CACTLA4IgG. The production of antibody against adenovirus was completely prevented after treatment with Adex1CACTLA4IgG. In addition, coadministration of Adex1CALacZ with Adex1CACTLA4IgG induced persistent hepatic expression of β-Gal molecules, while administration of Adex1CALacZ alone induced transient expression of β-Gal molecules. More importantly, on day 160 a secondary challenge with Adex1CALacZ was possible in mice treated with Adex1CALacZ plus Adex1CACTLA4IgG. Thus, we have demonstrated that (1) gene expression of a recombinant adenovirus, Adex1CACTLA4IgG, is persistent in liver and secondary administration of this adenovirus is possible, (2) coadministration of Adex1CACTLA4IgG virus with another adenovirus, AdexCALacZ, prolongs AdexCALacZ-mediated gene expression, and (3) Adex1CACTLA4IgG is useful for secondary challenge with Adex1CALacZ. Adenovirus vectors can transfer recombinant genes efficiently into a wide variety of cells in vivo, but have serious limitations because of immune responses against adenovirus-transduced cells. To solve the limitations, we have constructed an adenovirus vector, Adex1CACTLA4IgG, that expresses CTLA4IgG molecules. After in vivo administration of Adex1CACTLA4IgG, the production of CTLA4IgG molecules in sera persisted for more than 90 days and the production of antibody against the adenovirus itself was completely prevented. It is demonstrated that gene expression of a recombinant adenovirus, Adex1CACTLA4IgG, is persistent in liver and secondary administration of another adenovirus, Adex1CALacZ, is possible and efficient.