Growth stimulation of chick embryo neuroretinal cells infected with Rous sarcoma virus: Relationship to viral replication and morphological transformation

Abstract

Neuroretinal (NR) cells from 7-day-old chick embryos infected with Rous sarcoma virus (RSV) are morphologically transformed, synthesize virus, and are induced to proliferate for several generations. By contrast, uninfected cells have a limited growth capacity and cannot be propagated in vitro. The relationship of induction of cell multiplication to viral replication and morphological transformation was analyzed by infecting NR cells with conditional and nonconditional transformation defective viruses. NR cells infected with a temperature-sensitive mutant of RSV defective for cell transformation, but not for virus replication, were induced to multiply at both nonpermissive and permissive temperatures, although expression of the transformed phenotype, as tested by several parameters, was suppressed in these cells at nonpermissive temperature. Nonconditional, nontransforming viruses replicated normally in NR cells, but failed to induce their multiplication. These results indicate that only transforming viruses can induce NR cell multiplication and that viral replication alone does not account for the growth changes in infected NR cells. These data also suggest that expression of the transformed phenotype and induction of NR cell proliferation may depend on distinct viral informations.