Using less stringent hybridization conditions and cloned viral DNA probes representing the avian sarcoma virus gag, pol, env, and long terminal repeat (LTR) gene sequences, we detected related sequences in two avian species purportedly lacking all endogenous avian leukosis viruses, the ev- chicken and the Japanese quail. The blot hybridization patterns obtained with the various probes suggest t...

Avian interspecific brood parasites differ considerably in their commitment to parasitism; 87 species are obligate brood parasites, whereas 35 species are known to be facultative brood parasites. This variation is strongly related to mode of development. Obligate parasitism is found almost exclusively in altricial species, whereas facultative interspecific parasitism is predominant in precocial...

The genome of nearly all chickens contains various DNA proviral insertions of retroviruses of subgroup E avian leukosis virus (ALVE). However, the elimination or control of ALVE gene expression is desirable to improve productivity, to improve resistance to avian leukosis virus (ALV)-induced tumours, and to develop safer live virus vaccines in chick embryos and cultured chick cells. Restriction ...

Osteochondrosarcoma developed in a chicken inoculated with leukosis of Strain 2. In successive passages made by intramuscular implantation of tumor tissue deriving from this chicken there occurred (a) osteochondrosarcoma free from leukosis, or (b) leukosis free from osteochondrosarcoma, or (c) osteochondrosarcoma in association with leukosis. The malignant sarcoma cells of this strain have the ...