Heparin binding of chimeras containing (black) and lacking (white) the AAV2 heparin-binding domain (HBD) was analyzed using a heparin affinity column. Q-PCR was used to quantify the number of viruses that did not bind to the column, the number that eluted when the column was washed with buffer, and the number that eluted when the column was washed with buffers containing 250 mM, 650 mM, and 5 M NaCl. For each virus, the number of genomes detected by Q-PCR in all of the salt elutions was divided by the total number of viruses collected from the initial unbound flow-through, buffer wash, and salt elutions. Error bars indicate the SEM calculated from three independent experiments.