The transgene consists of a lymphotrophic papovavirus (LPV) enhancer/early promoter and an SV40 T antigen sequence which cannot express the small t antigen due to a deletion of the splice donor site. The Large T antigen retains Trp53 and Rb1/p107 binding function. Regulatory sequences direct expression of the transgene in B- and T- lymphocytes and choroid plexus epithelium. (J:72121)