FIG. 3.

Density gradient centrifugation of in vitro-packaged pTRLacZ virus and wild-type AAV packaged in vivo. In vitro-packaged pTRLacZ virus and wild-type AAV produced in vivo were centrifuged in parallel cesium chloride density gradients as described in Materials and Methods. The pTRLacZ virus titer (solid circles) was determined with the β-gal staining method; the wild-type AAV titer (open circles) was determined by the infectious-center assay. The virus preparations were heated at 55°C for 30 min prior to centrifugation in CsCl but were not treated with chloroform. ×, refractive index.