Viruses Intro

Question 1

Structural components

Answer 1

1. Capsids: protein shell contains DNA
2. Envelope: lipid bilateral membrane from host cell
3. Genome
   A. DNA
   B. RNA
   
   1. (+) sense
   2. (-) sense
      C. Ss
      D. ds

Question 2

Capsid shape

Answer 2

1. Icosahedral
2. Helical
3. Complex

Question 3

Viral replication cycle

Answer 3

1. Attachment: specific interaction w/ host cell
2. Entry
3. Uncoating genome
4. Viral gene expression
   A. Transcription
   B. Translation
5. Viral genome replication
6. Assembly
7. Matuaration and egress

Question 4

Classification of viruses

Answer 4

1. Nucleic acid
  A. Replication strategy
  B. Genome replication
2. Structure
  A. Capsid shape
  B. Presence of an envelope
3. Types of disease
  A. Upper resp tract infections
  B. Meningitis
  **many viruses = same clinical presentation

Question 5

Cytopathic effects

Answer 5

1. Consequences of viral replication
   A. Lytic infection (Rhinovirus)
   B. Syncytium formation: membrane fusion from neighboring cell to infected
   
   1. HIV
   2. Only enveloped viruses
      C. Hyperplasia: too much cell replication
   3. Epstein Barr virus
   4. Papilloma virus
      D. Transformation
   5. HTLV
   6. T-cell leukemia virus - only one to directly cause cancer

Question 6

Consequences of infection

Answer 6

1. No clinical presentation
2. Acute disease resulting from viral replication
3. Persistent/latent infection
   A. Herpes simplex virus
   B. Measles
4. Immunopathological rxn
5. Altered development
   A. Rubella virus, cytomegalovirus

Question 7

Patterns of viral infection

Answer 7

1. Acute followed by clearing
  A. Rhinovirus
  B. Rotavirus
  C. Influenza virus
2. Chronic infections
  A. Hepatitis B and C
3. Latent, reactivating infection
  A. Herpes simplex virus
4. Slow virus infection
  A. Measles virus SSPE
  B. Human immunodeficiency virus

Question 8

Viral factors

Answer 8

1. Virus host range
2. Viral virulence
   A. Polio- not very virulent
3. Number of viral particles present in inoculum