In vitro and in vivo Expression of AAV8-encoding Anti-CCR4 h1567 A modified scFvFc minibody format was used as the antibody moiety in the AAV8 vector, in which the V domains of heavy (VH) and light (VL) chains of the humanized scFv h1567 were fused to the coding region of the hinge and constant domains 2 and 3 (CH2 and CH3) of the human IgG1 heavy chain, to yield bivalent binding to the target molecule hCCR4 (Figure 1a ) (DK. Chang et al., in press). The resulting recombinant AAV8 vector was used for both in vitro protein synthesis and virus production for in vivo antibody gene delivery. In a pilot dosing study, nude mice received a single injection of two different concentrations of AAV8-h1567 via intravenous tail vein injection. Serum h1567 minibody levels were followed for 15 weeks. H1567 minibody levels rose for the first 2-3 weeks, reaching levels of circa 65 and 96 ug/ml for the low (0.8610 11 vg/mouse) and high (2.0610 11 vg/mouse) vector doses, respectively and then through the remaining weeks of the study leveled off at near peak levels for the high dosed vector and circa 1/3rd that level (,35 ug/ml) for the low dosed vector ( Figure S1 ). Because 2610 11 vg per mouse gave higher serum levels of h1567, this vector concentration was used in the subsequent in vivo studies.