Tissue distribution of the Rous sarcoma virus during the incubation period.

The Rous chicken sarcoma and its causative virus have been intensively studied since Peyton Rous first reported the transmissibility of the tumor by a filtrable agent (10). I t is known that Rous sarcoma virus (RSV) can propagate in tissues other than tumor. Groupe and Rauscher (4) demonstrated progressive propagation in chicken brain after intracerebral inoculation. Groupe et al. (5) found virus in the hemorrhagic lesions in liver which followed serial intracerebral passage of RSV in chicks. Milford and Duran-Reynals (8) demonstrated virus in viscera of chick embryos with hemorrhagic lesions induced by intravenous administration of Rous sarcoma filtrates. Karnofsky et al. (6) found virus in liver and other embryo tissues during growth of Rous sarcoma grafts on the chorioallantoic membrane (CAM). The appearance of diffuse hemorrhagic lesions in young chicks (8) after intravenous inoculation of virus probably also reflects virus propagation in viscera. Rous (1 l) demonstrated virus in the serum of some fowls with advanced sarcoma, and the observation has been confirmed by several later investigators (see literature review in Ref. 3). There has not, however, been any systematic study of the distribution of the virus during the incubation period. The present study was designed to determine whether there is a phase of systemic virus distribution during the incubation period, following local inoculation, as frequently occurs with other types of viruses, and, if so, to observe the relationship between virus distribution and the occurrence of tumors. The development of the CAM pock-count technic (7) provided a practicable method for such a study.