title: Theta particles: a structure found in hamster sarcoma virus.
abstract: Hamster sarcoma virus (HaSV), a ribonucleic acid tumor virus, pelleted from tissue culture fluid manifests type C morphology by electron microscopy. However, if virus is first concentrated by polyethylene glycol or ammonium sulfate followed by density gradient banding, the virus shows a dramatically atypical barred core structure, termed "theta particles." This structure suggests a condensation of the ribonucleoprotein into a flat disc. Atypical particles are found with HaSV and not in similarly treated feline leukemia virus or Rauscher-murine leukemia virus. Differences in the composition of HaSV as compared with these other viruses may be responsible for the production of such particles.
mesh_terms: D000645:Ammonium Sulfate; D000818:Animals; D002474:Cell-Free System; D002499:Centrifugation, Density Gradient; D011232:Chemical Precipitation; D006224:Cricetinae; D006018:Glycols; D005256:Leukemia Virus, Feline / Q000032:analysis / Q000302:isolation & purification; D008851:Micropore Filters; D008854:Microscopy, Electron; D009698:Nucleoproteins; D009858:Oncogenic Viruses / Q000032:analysis / Q000302:isolation & purification; D012328:RNA Viruses / Q000032:analysis / Q000302:isolation & purification; D011925:Rauscher Virus / Q000032:analysis / Q000302:isolation & purification; D012513:Sarcoma, Experimental / Q000382:microbiology*; D013194:Staining and Labeling; D013395:Sucrose; D014776:Virus Cultivation
chemical_list: D006018:Glycols; D009698:Nucleoproteins; D013395:Sucrose; D000645:Ammonium Sulfate