Retinoblastoma-like tumors induced by human adenovirus type 12 in rats.

SUMMARY A malignant intraocular neoplasm that resembled human retinoblastomas was produced in CD rats by injection of human adenovirus type 12. Fluid (0.01 ml), containing adenovirus type 12, l0@@ 50% tissue culture infective doses/mI, from culture fluids ofhuman embryo kidney cells was injected into the vitreous cavity of each newborn rat. Three of 35 virus-injected rats developed an intraocular tumor. Fifty additionalrats werepretreatedwith methylni trosourea on the 20th day of gestation; five of their offspring also developed tumors after virus injection. Pretreatment with methylnitrosourea remarkably reduced the latency period for tumor production. Histopathologically, tumor cells showed a marked tendency to form rosettes. A solitary cilium consisting of a typical ring of nine doublets with no axial pair (a 9 + 0 pattern) was frequently detected in the apical region of tumor cell cytoplasm. Adenovirus 12-spe cific T-antigen-positive particles were detectable in cells from the primary tumor tissue cultures with the immuno fluorescein procedure.