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 [insert Viral_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 helixB-pleated sheet

13 Prions: Characteristics [insert Prions_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 [insert Prions_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 [insert Prions_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 [insert Viral_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