The possibility to overcome species and age resistance in the induction of a neoplastic process by an avian tumour virus.
D000367:Age Factors; D000818:Animals; D001354:Avian Leukosis Virus; D001358:Avian Sarcoma Viruses; D002642:Chick Embryo; D051379:Mice; D009374:Neoplasms, Experimental / Q000276:immunology*; D001357:Sarcoma, Avian / Q000276:immunology*