Tissue tropism and temporal expression of Rous sarcoma virus in embryonic avian limb in ovo.

Embryonic avian tissue is resistant to the transforming potential of Rous sarcoma virus (RSV) in ovo. Analysis of the pattern of host-viral interactions in the first semester of chick development has demonstrated that RSV is first expressed in a limited population of muscle precursor cells and proceeds to spread throughout the developing dorsal and ventral limb musculature. The number of non-muscle cells participating in the infection is initially low but gradually increases as development continues. The data show that RSV infection in ovo is both compatible with the process of differentiation and the maintenance of the differentiated state of the limb. The kinetics of viral spreading and competence for transformation are developmentally regulated in the embryo. The contrasting properties of embryonic cells in ovo as compared with those of the adult provide an opportunity for evaluating host related regulatory factors that are of significance to the expression of viral transforming function.