Microbiology ch 13

  1. What are some General characteristics of Viruses?
    • -Obligatory intracellular parasites 
    • -Contain DNA or RNA
    • -Contain a protein coat
    • -Some are enclosed by an envelope
    • -some viruses have spikes
    • -most viruses infect only specific types of cells in one host
    • -Host range is deteremined by speficif host attachement sites and cellular factors.  
  2. What are some Virion structures?
    • -Nucleic acid -----DNA or RNA 
    • -Capsid-----Capsomeres
    • -Envelope
    • -Spikes
  3. Taxonomy of Viruses

    What  do family names end in? 
  4. Taxonomy of Viruses

    What do Genus names end in? 
  5. What are viral species?
    A group of viruses sharing the same genetic information and ecological niche(host). Comon names are used for species 

    Subspecies are designated by a number.  
  6. Taxonomy of Viruses

    • * Herpesviridae
    • * Retroviridae

    • *Herpesvirus
    • *Lentivirus

    -Human herpes virus-- HHV-1, HHV-2, HHV-3

    • -Human immunodeficiency virus HIV-1, HIV2
  7. Growing Viruses

    Viruses must be grown in living cells
    Bacteriophages form plaques on a lawn of bacteria 
  8. Growing viruses
    Animal viruse may be grown in living animals or in embryonated eggs
  9. Animal and plant viruses may be grown in cell culture
    continuouss cell lines may be maintained indefinitely 
  10. Virus Identification

    -Cytopathic effects
    -serological tests
    -Nucleic acids
    • serological tests
    • -detect antibodies against viruses in a patient
    • -uses antibodies to identify viruses in netralization tests, viral hemagglutination, and Western blot 
  11. What is the Lytic Cycle
    • -Attachment
    • -Penetration
    • -Biosynthesis
    • -Maturation
    • -Release
  12. Lytic Cyle


    Phage attaches by tail fibers to host cell
  13. Lytic Cycle

    Phage lysozyme opens cell wall, tail sheath contracts to force tail core and DNA into cell
  14. Lytic cycle

    Production of phage DNA and proteins
  15. Lytic Cycle

    Assembly of phage particles
  16. Lytic cycle

    Phage lysozyme breaks cell wall
  17. Results of Multiplication of Bacteriophages

    Lytic Cycle 
    Phages causes lysis and death of host cell
  18. Results of Multiplication of Bacteriophages

    Lysogenic Cycle
    • -Prophage DNA incoporated in host DNA
    • -Phage conversion
    • -Specialized transduction
  19. What are Lysogenic Cells
    • -Latent cells
    • -possible prophage (insertion into bacterial chromosome)
    • -three results of lysogeny:
    •         *immune to reinfection
    •         *phage conversion
    •         *specialized transduction
  20. Multiplication of Animal Viruses

    -What is the extra step 
    • -Attachment: viruses attach to cell membrane
    • -Penetration: by endocytosis or fusion
    • -Uncoating: by viral or host enzymes
    • -biosynthesis:production of nucleic acid and proteins
    • -Maturation: nucleic acid and capsid proteins assemble
    • -Release: by budding (enveloped viruses) or rupture 
  21. Attachment, Penetration, Uncoating
    Happens by pinocytosis
  22. Attachment, Penetration, Uncoating
    By Fusion
  23. Cancer
    • -Activated oncogenes transform normal cells into cancerous cells
    • -Transformed cells have increased growth, loss of contact inhibition, tumor-specific transplant antigens, and T antigens
    • -The genetic material of oncogenic viruses becomes integrated into the host cell's DNA 
  24. What are Oncogenic DNA Viruses?
    • -Adenoviridae
    • -Herpesviridae
    • -Poxviridae
    • -Papovaviridae
    • -Hepadnaviridae
  25. What are Oncogenic RNA viruses?
    • -Retroviridae
    • -Viral RNA is transcribed to DNA, which can integrate into host DNA
    • -HTLV-1
    • -HTLV-2 
  26. What happens during Latent viral infections
    Virus remains in asympotmatic host cell for long periods

    -COld sores, shingles 
  27. What happens in Persistent viral infections? 
    • -Disease processes occurs over a long period; generally is fatal
    •     *subacute sclerosing panencephalitis (measles virus)  
  28. What are prions?
    A prion is a protein.

    • -Proteinaceous infection particle
    • -Inherited and transmissible by ingestion, transplant, and surgical instruments
    •      -spongiform encephalopathies: sheep scrapie, Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker syndrome, fatal familial insomnia, mad cow disease

    **Must come in contact with brain to be infected with any prion disease  
  29. Prions
    PrPc: Normal cellular prion protein, on cell surface

    PrPsc: Scrapie protein; accumulates in brain cells, forming plaques  
  30. What are plant viruses?
    Enter through wounds or via insects
  31. What are viroids?
    Infectious RNA 

    -potato spindle tuber disease

    **only found to infect plants. Very specific, can only infect plants
  32. How can a protein become infectious?
    Become plaque or build up of proteins 
  33. What is orthomyxovirdae?
    • -Single-stranded RNA, 
    •     -each strand, has multiple RNA strands

    • -enveloped spikes can agglutinate RBCs
    • -Influenzavirus (influenza viruses A and B)
    • -Influenza C virus  
Card Set
Microbiology ch 13
review chapter 13