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Virology > Intro > Flashcards

Intro Flashcards

1
Q

Definitions!

A

-virology = study of viruses & viral disease
-virologist = someone who studies viruses
-virion = complete virus particle (RNA or DNA) + protein coat w external envelope (external infective form)
-virus = infectious agent: virion or inactivated virus particle or virtual nucleic acid & protein in infected cell (broad)
-viroid = infectious particle smaller than viruses, agent of plant disease, small circular RNA (lack protein coat) NOT A VIRUS

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2
Q

Describe why veterinary virology is important.

A

-high rates of mortality & morbidity
-financial loss
-zoonosis

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3
Q

Describe virus.

A

-non living
-nucleic acid genome (DNA or RNA) surrounded by protein coat (sometimes lipid envelope)
-no cell organelles
-cant make energy or proteins by themself
-obligate intracellular parasites
-no genetic capability to multiply by division
-reproduction via assembly line

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4
Q

Describe Edward Jenner.

A

-inoculated cowpox matter into boy -> became immune to small pox
-vacca = cow
-vaccine invented

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5
Q

Describe Louis Pasteur.

A

-injected dried potassium hydroxide treated infected rabbit brain material into boys bitten by rabid dogs & both recovered

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6
Q

Describe the Chamberland filter.

A

-filter has pores smaller than bacteria
-pioneered discovery of viruses
-used in famous tobacco mosaic virus experiment

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7
Q

Describe Dmitri Ivanoski.

A
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8
Q

Describe Friedrich Loeffler & Paul Frisch.

A

-passed first animal virus thru similar filter
-discovered the cause of foot & mouth disease virus

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9
Q

Describe Walter Reed.

A

-discovered yellow fever is transmitted thru mosquitos

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10
Q

Describe Peyton Rous.

A

-discovery of oncogenic viruses
-isolated first tumor causing animal virus
-‘rous sarcoma virus’

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11
Q

Describe Ernst Ruska & Max Knoll.

A

-invention of electron microscope

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12
Q

Describe the fowl pox virus.

A

-1st virus to successfully propagated in embryo aged hen egg

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13
Q

Describe tissue culture.

A
  1. Sanford = culture of isolated mammalian cells
  2. Enders = growth of poliovirus in cell culture
  3. Dulbecco & Vogt = plaque assay for first animal virus polio virus
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14
Q

Describe rinderpest.

A

-only animal disease declared globally eradicated

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15
Q

Describe the Baltimore Classification system.

A

-old system (not used anymore)
-based on viral genome

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16
Q

Describe ICTV.

A

-international committee on taxonomy of viruses
-currently used to classify viruses
-charged by international union of microbio societies w task of developing, refining, & maintaining universal virus taxonomy
-considers:
>nature of virus genome & virus genetic diversity
>virus replication strategy
>virus morphology

17
Q

Describe the smallest VS the largest virus.

A
  1. Smallest
    -porcine circovrius type 1
  2. Largest
    -pox virus in animals, humans, birds
18
Q

Describe pleomorphism.

A

-ability of virus to alter shape or size

19
Q

Describe the common methods used to determine the morphology of viruses.

A
  1. electron microscope (EM)
  2. cryo-electron microscope (cryo-EM)
  3. x ray crystallographic method
  4. Nuclear magnetic resonance (NMR)
20
Q

Describe the morphology of viruses.

A

-capsid = protein shell of virus that encases viral nucleic acid or genome
>made up of capsomeres
—basic subunit protein in the capsid of a virus
>most viruses have one capsid expect reoviruses (double layered capsid)

21
Q

Describe nucleocapsid.

A

Capsid + Virus Nucleic acid (DNA or RNA)/Genome

22
Q

Describe helical symmetry.

A

-in all animal viruses the helical nucleocapid is enclosed within lipoprotein envelope
-naked helical nucleocapsids common in plant viruses like tobacco mosaic virus

23
Q

Describe cubic/icosahedral symmetry.

A

-2 types of capsomers present in icosahedral capsid
-pentagonal capsomers at vertices (pentons) & the hexagonal capsomers making up the facets (hexons)
-always 12 pentons but # of hexons varies w virus group
-triangulation # (T#) = describes relation between the # of pentagons & hexagons of the icosahedron
FORMULA:
T = h^2 + (h)(k) + k^2
[h&k are the distance between successive pentagons on the virus surface for each axis]

24
Q

Describe complex symmetry.

A

Pox virus

25
Q

Describe the functions of the viral capsid.

A
  1. Resp for structural symmetry of virus particle
  2. Encases & protects viral nucleic acid from enzymes (nucleases), chemicals, & physical conditions (pH & temp)
  3. Receptor attachment proteins on viral capsid for attachment of the virus to receptors on host
  4. Interaction w host cell membrane to form the envelope
  5. Uncoating of the genome in host cell
  6. Transport of the viral genome to the appropriate site
  7. Packaging of nucleic acid genome
  8. Contains antigenic sites & determines antigenicity of virus
26
Q

Describe enveloped viruses.

A

-envelope = lipid bilayer with embedded proteins
>acquired by budding of viral nucleocapsid thru cell membrane like cytoplasmic membrane, golgi membrane, or nucleus membrane
>2 kinds of viral proteins found in envelope: glycoprotein & matrix protein

27
Q

Describe the virus envelope glycoproteins.

A
  1. External glycoprotein
    -major antigen of virus
    -hemagglutination, receptor binding, antigenicity, membrane function
  2. Channel proteins
    -hydrophobic proteins that form protein lined channel thru envelope
    -alters permeability of membrane
    -modify internal environment of virus
28
Q

Describe the virus envelope matrix protein.

A

-link internal nucleocapsid to the lipid membrane envelope
-role in virus assembly
-stabilization of lipid envelope
-recognition site of nucleocapsid at the PM
-mediates encapsidation of the RNA-nucleoprotein cores into membrane envelope

29
Q

Describe the lipid bi layer in virus envelope.

A

-from cell membrane of host like cytoplasmic membrane, nuclear, membrane, ER membrane
-in aqueous or moist environment (lipid envelope sensitive to desiccation, heat, alteration of pH)
-enveloped virus inactivated by dissolution of lipid membrane with lipid solvents:
>ether, chloroform, sodium deoxycholate, detergents
enveloped viruses easy to sterilize than non enveloped viruses & cant survive for longer periods in environment

30
Q

Describe nucleic acids.

A
31
Q

Describe the mechanisms of generic diversity of viruses.

A
  1. Antigenic drift = mutations (ex. Point mutation)
  2. Antigenic shift = recombination (singe gene seg)
    -intramolecular recombination involves the exchanged of nucleotide seq between diff but closely related viruses during replication
    -reassortment most IMP for high genetic diversity in viruses w segmented genome (more than one gene seg)
32
Q

Describe viral enzymes.

A
  1. Retroviral integrate (IN)
    -enzyme made by retrovirus (HIV) that allows genetic material to be integrated into DNA of infected cell
  2. Reverse transcriptase (RT)
    -enzyme used to gen complementary DNA (cDNA) from a RNA template
  3. Nucleic acid polymerase
    -viral genome replication
33
Q

Describe viral nonstructural proteins.

A

-proteins play role in infected cell during virus replication or act in regulation of virus replication or virus assembly

34
Q

Describe an incomplete, defective, psuedotype & pseudo virion.

A
  1. Incomplete virion
    -virus w/o nucleic acid (empty capsid)
  2. Defective virion
    -virus that cant replicate bc its lacks full complement/copy of viral genes
    -defective viral particles result from mutations or errors in production or assembly of virions
  3. Pseudovirion
    -non viral genome within viral capsid like host nucleic acid instead of viral nucleic acid
  4. Psuedotypes
    -when related viruses infect the same cell
    -genome of one virus may be enclosed in the heterologous capsid of the second virus

Virology (24 decks)

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