title: Interaction among avian tumor viruses giving enhanced infectivity.
mesh_terms: D000818:Animals; D001354:Avian Leukosis Virus; D001358:Avian Sarcoma Viruses; D002642:Chick Embryo; D006378:Helper Viruses; D014316:Tritium; D014357:Trypsin / Q000494:pharmacology
chemical_list: D014316:Tritium; D014357:Trypsin