Southern blot analysis of high-molecular-weight DNA extracted from muscles. Entire tibialis anterior muscles were resected from animals killed 29 weeks after vector injection and used for high-molecular-weight DNA extraction. HD mice, animals injected with 2.5 × 10¹⁰ rAAV-ET genomes in each tibialis anterior; LD mice, animals injected with 2.5 × 10¹⁰ rAAV-ET genomes in a single tibialis anterior; i.m., rAAV-ET injected muscle; n.i.m., controlateral muscle not injected with the vector. Undigested (−) andBamHI digested (+) DNA was hybridized with a³²P-labeled Epo-specific probe. Reference copy numbers (ref. copy number) correspond to high-molecular-weight DNA extracted from normal C3H mouse muscle and run with plasmid DNAs corresponding to 1 copy (20 pg, lane 1) or 0.1 copy (2 pg, lane 0.1) of pAAV-ET DNA. (C) DNA extracted from a muscle of a noninjected mouse. Signals corresponding to the endogenous Epo gene (Epo endo) and to the internalBamHI vector fragment are indicated. Precise quantification of vector signals relative to ref. copy number signals and Epo endo signals was done on a phosphorimager. Molecular weight markers are in kilobases.