title: Studies on DNA from low-density particles of SV40. I. Heterogeneous defective virions produced by successive undiluted passages.
mesh_terms: D002499:Centrifugation, Density Gradient; D002501:Centrifugation, Zonal; D046508:Culture Techniques; D003588:Cytopathogenic Effect, Viral; D004279:DNA, Viral / Q000032:analysis; D003673:Defective Viruses; D008854:Microscopy, Electron; D013539:Simian virus 40; D014776:Virus Cultivation
chemical_list: D004279:DNA, Viral