AAV type 2-based regulated expression of secreted proteins. (A) Schematic representation of pDF77, harboring a SEAP expression cassette under the control of PETR, pDF143, a self-regulated expression unit expressing ET1 from PSV40 and driving SEAP from PETR and pDF109, harboring a constitutive SEAP expression unit driven by PhCMV (B) SEAP expression levels profiled 48 h after (co-)transduction of transgenic AAV particles (1000 genomic particles/cell for pDF51/77, 1000 genomic particles/cell for pDF143 and 1000 genomic particles/cell for pDF109) derived from indicated vectors and cultivated in the presence (+) or absence (-) of EM. SEAP expression is shown in units/liter (U/l) as defined by Schlatter et al. . Abbreviations: EM, erythromycin; ET1, erythromycin transactivator; ITR, inverted terminal repeat; pASV40, simian virus 40 polyadenylation signal; PhEF1α, human elongation factor 1α promoter; PETR, erythromycin-responsive promoter; SEAP, human placental secreted alkaline phosphatase; PSV40, simian virus 40 promoter.