loaded on a 15–65% (w/v) sucrose gradient prepared in PBS, and centrifuged
for 60 min at 110000 · g in a Beckman SW28 rotor. Bands
were visualized, aspirated from tubes, diluted 10-fold in PBS and repelleted.
Purified viral pellets were suspended and the viral DNA was
purified as described by Hutoran et al.