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Prions

Prions. Infectious proteins Inherited and transmissible by ingestion, transplant, and surgical instruments Spongiform encephalopathies: Sheep scrapie, Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, mad cow disease

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Prions

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  1. Prions • Infectious proteins • Inherited and transmissible by ingestion, transplant, and surgical instruments • Spongiform encephalopathies: Sheep scrapie, Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, mad cow disease • PrPC: Normal cellular prion protein, on cell surface • PrPSc: Scrapie protein; accumulates in brain cells forming plaques

  2. Prions Figure 13.22

  3. Plant viruses: Enter through wounds or via insects. • Viroids: Infectious RNA; e.g., potato spindle tuber disease. Figure 13.23

  4. Some Plant Viruses Table 13.6

  5. Virus Families • Single-stranded DNA, nonenveloped viruses • Parvoviridae • Human parvovirus • Fifth disease • Anemia in immunocompromised patients Table 13.2 (1 of 20)

  6. Single-Stranded RNA, + Strand, Nonenveloped • Enterovirus • Enteroviruses include poliovirus and coxsackievirus. • Rhinovirus • Hepatitis A virus Table 13.2 (7 of 20)

  7. Double-Stranded DNA, Nonenveloped Viruses • Mastadenovirus • Respiratory infections in humans • Tumors in animals Table 13.2 (2 of 20)

  8. Double-Stranded DNA, Nonenveloped Viruses • Papillomavirus (human wart virus) • Polyomavirus • Cause tumors; some cause cancer Table 13.2 (3 of 20)

  9. Double-Stranded DNA, Enveloped Viruses • Orthopoxvirus (vaccinia and smallpox viruses) • Molluscipoxvirus • Smallpox • Molluscum contagiosum • Cowpox Table 13.2 (4 of 20)

  10. Double-Stranded DNA, Enveloped Viruses • Simplexvirus (HHV1 and HHV 2) • Varicellavirus (HHV 3) • Lymphocryptovirus (HHV 4) • Cytomegalovirus (HHV 5) • Roseolovirus (HHV 6) • HHV 7 • Kaposi's sarcoma (HHV 8) • Some herpesviruses can remain latent in host cells. Table 13.2 (5 of 20)

  11. Double-Stranded DNA, Enveloped Viruses • Hepadnavirus (Hepatitis B virus) • Use reverse transcriptase to produce DNA from mRNA. Table 13.2 (6 of 20)

  12. Single-Stranded RNA, + Strand, Nonenveloped • Hepatitis E virus • Norovirus causes gastroenteritis. Table 13.2 (8 of 20)

  13. Single-Stranded RNA, + Strand, Enveloped • Alphavirus • Alphaviruses are transmitted by arthropods; include EEE, WEE. • Rubivirus (rubella virus) Table 13.2 (9 of 20)

  14. Single-Stranded RNA, + Strand, Enveloped • Arboviruses can replicate in arthropods; include yellow fever, dengue, SLE, and West Nile viruses • Hepatitis C virus Table 13.2 (10 of 20)

  15. Single-Stranded RNA, + Strand, Enveloped • Coronavirus • Upper respiratory infections • SARS Table 13.2 (11 of 20)

  16. Single-Stranded RNA, – Strand, One RNA Strand • Vesiculovirus • Lyssavirus (rabies virus) • Cause numerous animal diseases Table 13.2 (12 of 20)

  17. Single-Stranded RNA, – Strand, One RNA Strand • Filovirus • Enveloped, helical viruses • Ebola and Marburg viruses Table 13.2 (13 of 20)

  18. Single-Stranded RNA, – Strand, One RNA Strand • Paramyxovirus • Morbillivirus • Paramyxovirus • Parainfluenza • Mumps • Newcastle disease Table 13.2 (14 of 20)

  19. Single-Stranded RNA, – Strand, One RNA Strand • Hepatitis D virus • Depends on coinfection with Hepadnavirus Table 13.2 (15 of 20)

  20. Single-Stranded RNA, – Strand, Multiple RNA Strands • Influenzavirus (Influenza viruses A and B) • Influenza C virus • Envelope spikes can agglutinate RBCs. Table 13.2 (16 of 20)

  21. Crossing the Species Barrier UN 13.3

  22. Single-Stranded RNA, – Strand, Multiple RNA Strands • Bunyavirus (CE virus) • Hantavirus Table 13.2 (17 of 20)

  23. Single-Stranded RNA, – Strand, Multiple RNA Strands • Arenavirus • Helical capsids contain RNA-containing granules • Lymphocytic choriomeningitis • VEE and Lassa Fever Table 13.2 (18 of 20)

  24. Single-Stranded RNA, Two RNA Strands, Produce DNA • Lentivirus (HIV) • Oncogenic viruses • Use reverse transcriptase to produce DNA from viral genome. • Includes all RNA tumor viruses Table 13.2 (19 of 20)

  25. Double-Stranded RNA, Nonenveloped • Reovirus (Respiratory Enteric Orphan) • Rotavirus • Mild respiratory infections and gastroenteritis • Colorado tick fever Table 13.2 (20 of 20)

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