Polyoma tumor development in neonatally polyoma-virus-infected CD4−/− and CD8−/− single knockout and CD4−/−8−/− double knockout mice

CD4−/− or CD8−/− single knockout as well as CD4−/−8−/− double knockout mice were infected with polyoma virus as newborns or 1 week after birth. The animals were followed for tumor development and virus persistence. Double knockout mice developed tumors at a higher incidence (29%) than either the CD8−/− or CD4−/− single knockout mice (11% and 2%, respectively). Persistence of polyoma virus was examined by PCR in one third of all animals included in the study. Seven of the 17 CD4−/−8−/− double knockout mice gave positive evidence of virus persistence up to 6 months p.i. where virus DNA was present in most organs. Corresponding tests in single knockout mice gave positive results of persistent viral DNA in 2 of the 19 CD8−/− and 2 of the 7 CD4−/− mice. In the single knockout mice polyoma DNA could only be detected in a more limited variety of organs compared to the double knockouts. © 1996 Wiley-Liss, Inc.