Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

46 Cards in this Set

  • Front
  • Back
Definition of virus
Obligate intracellular parasite - depends on host's cell machinery to reproduce
- can be DNA or RNA
Viral lysogeny
Integration of viral DNA or RNA into host cell genome
Non permissive cell
Cell that will not allow replication of particular type of strain of virus
Permissive cell
Cell providing machinery for virus machinery
Latent infection
Infection that is restricted or lacks machinery for transcription of viral genes
Viral capsid
Protein structure enclosing nuclear genome of virus - very solid
Viral envelope
Layer surrounding and forming surface of virus - comes from host's phospholipid
Nucleic acid (DNA or RNA) + capsid (protein)
Viral spikes
Protein or glycoprotein structures on the surface of the virus (receptors)
What can bacteriophage do when it infects bacteria
- Antibiotic resistance
- Can kill bacteria helping in digestion - can get malabsorption
2 types of yellow fever
Yellow fever is a viral disease - presents with jaundice
2 types - jungular + urban
Jungular - from monkeys through mosquitos
Urban - from humans through mosquitos
Compare viruses and eukaryotic cells in terms of :
- Nucleic acid
- Lipoprotein membrane
- Ribosome
- Mitochondria
- Enzymes
Nucleic acid: viruses - DNA or RNA, cells - DNA and RNA
Proteins: viruses - few, cells- many
Lipoprotein membrane: viruses - envelope present in some, cells - cell membrane present in all
Ribosome: viruses - absent, cells - present
Mitochondria: viruses - absent, cells - present
Enzymes: viruses - none or few, cells - many
Example of small cell
Example of large cell
With exception of _ all DNA viruses replicate in _
99% of DNA viruses are _
Double stranded
2 types of RNA viruses have segmented RNA - name them
- Influenza - 8 segments
- Rotavirus - 11 segments
What kind of genome does DNA virus have
Morphology of viruses studies what?
- Size
- Shape
- Symmetry
- Presence or absence of peplomers (virus coded glycorpoteins on the surface of virus envelope)
- Presence or absence of membranes
Physicochemical properties of viruses
- Molecular mass
- Buoyancy (if envelope - more buoyant)
- pH stability
- thermal stability
- Susceptbility to detergents
Genome properties of viruses
- Genome - DNA or RNA
- Size of genome
- Type of strand - circular or linear
- Sense - positive or negative
- Segments (influenza)
What is responsible for cell attachment in influenza
- Neuraminidase
Name 3 types of viral architecture
- Cubic (icosahedral) - adenoviruses
- Helical - orthomyxoviruses
- Complex - poxvirus
What do peplomeres do
Play key role in viral attachment and induction of netralizing antibodies
- Also called glycoproteins or spikes
Describe cubic (icosahedral) architecture
Example - papilloma virus
2 components - capsid + genome
Capsid - aggregation of capsomeres
Core+ capsid - nucleocapsid
Describe icosahedral (cubic) + envelope architecture - give example
- Rubella virus
- Nucleocapsid is wrapped in outer envelope
- Between nuclecapsid and envelope is matrix protein
Describe helical architecture
-Flexible hollow tube - capsid proteins are aggregated around it
Name host responses to viruses
- Asymptomatic - HIV, herpes
- Induction of cancers - HPV
- Chronic progressive neurological disorder
- Possible endocrine disease - diabetes
Cells can respond to viruses in 3 ways
- No apparent change
- CPE and death of cell
- Loss of growth control (transformation) - interfere with cell cycle (no check points)
3 basic patterns of infection in viral disease
- Localized
- Disseminated
- Inapparent
2 types of viremia
Primary viremia - spread to other susceptible organs such as liver and spleen
Secondary viremia - dissemination to other organs such as skin
Difference between primary and secondary viremia
High number of viruses - secondary viremia
Describe entry into the host
- Skin - most viruses enter through breach of physical integrity of skin, many viruses employ vectors
- GI tract - enveloped viruses cannot survive highly acidic environment
- Respiratory - influenza
- Genitourinary - HPV, herpes
- Conjunctiva - adenovirus
Give examples of localized infections
- Respiratory - rhinoviruses - cause common cold
- Rotaviruses - GI - cause infantile diarrhea
- Papilloma virus - genital and skin epidermis - HPV
Give examples of systemic infection
- Enteroviruses - primary replication in GI, secondary - lymph and CNS
- Herpes virus - primary replication in oropharynx or genitourinary tract, secondary - lymph or CNS
Which virus likes to hide in nervous system and where
Herpes virus likes to hide in nervous system - in DRG
2 main mechanisms of viral spread through host
- Blood
- Nervous tissue
`How do viruses spread in nervous system
- By direct contact with neurons at the primary site of infection or through blood
- They spread from peripheral nerves through AXONAL TRANSPORT
What is a secondary replication
- Poliovirus- gut (primary) neurons and spinal cord (secondary)
- HIV - macrophages and CNS
- Occurs
Antigenic shift and drift are common in what virus
Antigenic drift
Gradual accumulation of minor mutations
Net result - altered antigenicity
Eventually immune system recognizes virus and clears it
Antigenic shift
Sudden and major change in antigenicity
Due to RECOMBINATION of virus genome with genome of another antigenicity
Immune system cannot recognize this change and virus becomes very severe
What allows influenza to undergo shift and drift
NA - neuroaminidase
HA - hemoagglutinin
Name slow viral infections
Measles- subacute sclerosing panencephalitis
Describe subacute sclerosing panencephalitis
- Profound atrophy of cortex
- Loss of white matter
- Ventricular enlargement
Describe progressive multifocal leukoencephalopathy (PML)
- Giant astrocytes
- Oligodendrocyte inclusions