Decrease of Delta4-transduced spleen cells in late-stage disease.

Spleens were harvested 10 (10 W) and 15 (15 W) weeks after transplantation from animals transduced with control virus or viruses carrying either full-length (Delta4) or secreted Delta4 (Delta4sec). Southern blot analysis for proviral integration was generated from genomic DNA digested with XbaI. A cDNA fragment corresponding to the extracellular domain of Delta4 was used as a probe. XbaI cuts in the retroviral LTR and releases a 4.75-kb fragment for full-length Delta4 and a 4.25-kb fragment for secreted Delta4. The endogenous (endo) and retroviral (RT) Delta4 bands are indicated.