Adenovirus type 5 persisting in human lymphocytes is unlikely to be involved in immortalization of lymphoid cells by fusion with cytoplasts or by transfection with DNA of mouse L cells.

Human peripheral blood lymphocytes were induced to proliferate indefinitely in vitro by fusion with cytoplasts from mouse L 929 cells or, alternatively, by transfection with DNA isolated from L929 cytoplasts. Since adenoviruses epidemically infect human lymphocytes, the newly established cell lines were assayed for the presence of adenoviral DNA sequences. In 8 of 10 lymphoid cell lines of both B and T cell origin, adenovirus type 5 (serogroup C) DNA sequences were detected. The cells harbor approximately 40 to 70 genome copies per cell. Adenovirus type 5 transcripts of the E1A and E1B early regions that are responsible for the transforming capacity of adenoviruses could not be detected in the lymphoid cell lines. Therefore we conclude that the adenovirus genome persisting in immortalized lymphoid cells is not involved in the maintenance of indefinite proliferation induced by fusion with L929 cytoplasts or by DNA transfection.