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VIRUSES and prions

VIRUSES and prions. CHAPTER 10 : part 2. Viruses part II - Animals and Plants. Unique challenges. Must evade immune systems and must cross 2 lipid bilayer barriers. (ie cross into nucleus). Viral Replication: Animal Viruses . [insert Viral_Rep_Animal.jpg ]. RNA Virus Families.

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VIRUSES and prions

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  1. VIRUSES and prions CHAPTER 10 : part 2

  2. Viruses part II - Animals and Plants Unique challenges. Must evade immune systems and must cross 2 lipid bilayer barriers. (ie cross into nucleus)

  3. Viral Replication: Animal Viruses [insertViral_Rep_Animal.jpg]

  4. RNA Virus Families • 11 RNA virus families • Picornaviridae (fmdv, polio) • Togaviridae (rubella) • Flaviviridae (hep C, west nile, yellow fever) • Orthomyxoviridae (flu, influenza) RNA viruses more prone to mutation

  5. RNA Virus Families (cont.) • Retroviridae (hep B, htlv, HIV)-retrovirus • reverse transcriptase used to make DNA • from RNA • Paramyxoviridae (measles, mumps, pneumonia) - ss strand

  6. RNA Virus Families (cont.) • Rhabdoviridae (rabies)

  7. RNA Virus Families (cont.) • Orthomyxoviridae (all influenza) Hemaglutinnin H Neuraminidase N

  8. DNA Virus Families • Adenoviridae (colds) • Herpesviridae (varicellovirus, simplex virus) • affinity for nervous tissue • Poxviridae (smallpox)

  9. DNA Virus Families (cont.) • Papovaviridae (HPV) • Hepadnaviridae (Hep B virus)

  10. Viral Replication • Activities • Adsorption • Penetration (virus or chromosome) • Synthesis • Maturation • Release

  11. Animal Viruses • DNA viruses

  12. Viruslike Agents • Prions Kuru Creutzfeld-Jacob BSE Scrapie Alpha helix B-pleated sheet

  13. Prions: Characteristics [insertPrions_Character.jpg]

  14. The PrP protein function in mammals is believed to ________. • assist proteins in forming alpha helices. • assist proteins in forming beta-pleated sheets. • assist in normal synaptic development and function. • assist in normal membrane development and function.

  15. Which mammals code for PrP? • humans • cows • sheep • all mammals • Mammals are not affected by prions.

  16. Why is the term “reproduction” not appropriate in prion multiplication? • Prions occur only in mammals, so reproduction is a misnomer. • All mammals have PrP, so no reproduction is involved. • Prions are acquired only through ingestion, not by reproduction. • Prions transform normal proteins into the misfolded configuration; therefore, prions multiply by conversion.

  17. Prions: Overview [insertPrions_Overview.jpg]

  18. How do prions replicate? • binary fission • They cause normal proteins to misfold into infectious proteins. • mitosis • via DNA replication

  19. How are prions different from other infectious agents? • They cause neurological disease. • They lack protein. • They lack nucleic acid. • They cannot replicate.

  20. Why are the beta-pleated multimers of PrP potentially pathogenic? • They are not detected by other organisms. • They repress the immune system. • They are more stable as multimers and resistant to proteases. • They are found on the surface of immune cells, resulting in destruction of the immune system.

  21. Prion Reproduction: Diseases [insertPrions_Diseases.jpg]

  22. What is the incubation period of BSE? • 4 to 5 years • 3 days • 6 weeks • 7 months

  23. Which of the following human prion diseases is related to mad cow disease? • fatal familial insomnia • variant Creutzfeldt-Jakob disease • kuru • Gerstmann-Straussler-Scheinker syndrome

  24. Viruses and Cancer • Mechanism of cancer causation • HPV

  25. Viruses and Cancer • Oncogenes/proto-oncogenes • V-myc V-ras mimic our cells own control proteins Rous Sarcoma Virus RSV Kaposi’s sarcoma - appears when immune system depressed probably by herpes virus 8

  26. Viruses to know something about •HPV (DNA) • HIV (RNA) • Flu (RNA) • Adenovirus(DNA) • Herpes(DNA)

  27. Herpes Simplex After initial infection, the viruses move to sensory nerves, where they reside as life-long, latent viruses.

  28. HPV human papilloma virus • Causes warts and some strains cause cervical cancer • teratogenic

  29. Viral Replication: Temperate Bacteriophages [insertViral_Rep_Temperate.jpg]

  30. HIV human immunodeficiency virus • RNA retrovirus • T-cell host (CD4+ T-killer cells) • needs protease to replicate • binds to CCR5 and CD4 receptors

  31. Adenovirus • Common cold • Usually affects respiratory tract. • sometimes engineered for gene therapy • DS DNA virus

  32. Influenza H = hemaglutinin N = neuraminidase • RNA virus • mutates rapidly • animal reservoirs • can cross species lines

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