viruses, viroids, prions

• Viruses


  Can't multiply outside a living host cell
• Growing Bacteriophages in the Laboratory


  Bacteriophages can be grown either in suspensions of bacteria in liquid media or in bacterial cultures on solid media
• Viral Identification


  Viruses can't be seen without the use of an electron microscope
• Oncogenes


  Cancer-causing alterations to cellular DNA that affect parts of the genome
• Oncogenic viruses


  Viruses capable of inducing tumors in animals
• DNA Oncogenic Viruses


  • Adenoviridae
  • Herpesviridae
  • Poxviridae
  • Papovaviridae
  • Hepadnaviridae
• Virtually all cervical and anal cancers are caused by human papillomavirus (HPV)
• Another DNA virus that causes cancer is hepatitis B virus (HBV)
• RNA Oncogenic Viruses


  • Retroviruses in the family Retroviridae
• Prions


  Infectious proteins that cause neurological diseases
• Viroids


  Acellular particles that are virus-like
• The first viroid discovered was found to cause potato tuber spindle disease, which causes slower sprouting and various deformities in potato plants