Conditions favouring the emergence of host range variants during passage of a proxvirus.
D000818:Animals; D002460:Cell Line; D002501:Centrifugation, Zonal; D002642:Chick Embryo; D002999:Clone Cells; D046508:Culture Techniques; D005321:Extraembryonic Membranes; D014644:Genetic Variation; D007668:Kidney; D007739:L Cells; D051379:Mice; D008854:Microscopy, Electron; D011817:Rabbits; D014616:Vaccinia virus / Q000254:growth & development*; D010948:Viral Plaque Assay; D014776:Virus Cultivation