Integration of Rous-associated virus type O provirus in susceptible chicken cells.

The number of viral genome equivalents per haploid cell genome was determined in normal chicken embryos from three selected chicken lines and in cultured fibroblasts (CEF) from these embryos. The cellular concentration of endogenous proviral DNA is similar in embryos from chickens of lines SPAFAS, 7, 15, 7 x 15, and 100. The concentration of proviral DNA is not affected by in vitro cultivation in CEF from lines that do not spontaneously produce virus, nor in CEF from line 7, which lacks receptors for Rous-associated virus type 0 (RAV-0). There is, however, a restricted increase in the number of integrated proviral genome equivalents in CEF from line 7 x 15, which produces RAV-0 and can support replication of this virus, and in CEF from line 15 experimentally infected with RAV-0.