Factors affecting rAAV binding in C2C12 cells. (A) The effects of heparin competition or sialidase (NA III) treatment on rAAV-2 and rAAV-2cap5 virus infection in C2C12 cells were evaluated. rAAV-2 or rAAV-2cap5 infections (MOI of 1,000 DNA particles/cell) of undifferentiated (lanes 1 to 6) or differentiated (lanes 7 to 12) C2C12 cells were evaluated following no treatment (lanes 3, 6, 9, and 12), sialidase treatment (lanes 1, 4, 7, and 10), or heparin (final concentration, 20 μg/ml) competition (lanes 2, 5, 8, and 11). Hirt DNA was harvested after incubation at 4°C for 60 min and evaluated by Southern blotting against a 32P-labeled EGFP probe. Pseudo, rAAV-2cap5 virus. (B) Results from densitometric quantification of DNA signals from three independent experiments. NAIII, type III neuraminidase (sialidase). Values are represented as percent inhibition (means ± standard errors of the means [error bars]; n = 3) in binding following sialidase treatment or heparin competition compared to untreated controls.