A recombinant virus vector constructed from AAV1 has been altered to carry the human alpha-sarcoglycan gene expressed from a tMCK promoter. The construct has been shown to initiate the production of a functional alpha-sarcoglycan protein in laboratory animals. This construct can reverse the dystrophic phenotype in the alpha-sarcoglycan knock out mouse, a laboratory animal model for the clinical disorder. Intramuscular injection of rAAV1 restores muscle histology to normal and increases muscle strength to levels exceeding control knock out mice but not to the same degree as wild-type mice.