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Block 6 Week 4 > Viral Classification- Aucoin > Flashcards

Viral Classification- Aucoin Flashcards

1
Q

Viruses are (blank) agents.

A

Fiterable (can pass through a filter)

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2
Q

Viruses are (blank) intracellular parasites

A

obligate (restricted to a particular condition of life)

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3
Q

Can viruses make energy or proteins independently of a host cell?

A

NOOOOO

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4
Q

Viral genomes can be RNA, DNA or both?

A

They can be RNA or DNA but not both

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5
Q

Which do viruses have, a naked capsid or an envelope morphology?

A

Either or :)

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6
Q

Are viruses living?

A

no, they are not

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7
Q

What must viruses be to endure in nature?

A

infectious

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8
Q

Viruses have been optimized by (blank) and (blank) to infect humans and other hosts

A

mutation and selection

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9
Q

Viruses must be able to use (blank) to produce their components

A

host cell processes

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10
Q

Viruses must encode any required processes not provided by the cell. T or F

A

T

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11
Q

Viral components (blank) assemble

A

self

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12
Q

What are the 2 types of viruses you can have?

A

naked capsid viruses enveloped viruses

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13
Q

What makes up a naked capsid virus?

A

DNA or RNA + structural proteins +/- enzymatic and nucleic acid binding proteins= nucleocapsid=naked capsid virus

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14
Q

What are three examples of naked capsid viruses?

A

papilloma virus adenovirus poliovirus

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15
Q

What makes up an enveloped virus?

A

DNA or RNA + nucleocapsid + glycoproteins and membrane= enveloped virus

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16
Q

What are 2 examples of an enveloped virus?

A

herpesvirus retrovirus

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17
Q

What is a bacteriophage?

A

a virus that infects bacteria

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18
Q

Many viral proteins are packaged within the virion, possibly in the (blank) layer, between the capsid and envelope

A

tegument

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19
Q

What is a virion made up of?

A

nucleic acid genome packaged into a protein coat (capsid or ribonucleocapsid) or a membrane (envelope)

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20
Q

What is a virion?

A

infectious virus particle

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21
Q

(blank) can hold a larger genome and are generally more complex

A

larger virions

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22
Q

(blank) are almost visible with a light microscope (300 nm) this i 1/4 the size of staph

A

poxviruses

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23
Q

How do you measure virions?

A

in nanometers

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24
Q

What are the + RNA via DNA E viruses?

A

Retro

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25
Q

What are the +/- RNA (double capsid) viruses?

A

Reo

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26
Q

What are the -RNA E viruses?

A

Rhabado Filo Orthomyxo Paramyxo Bunya Arena

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27
Q

What are the + RNA E viruses?

A

Toga, Flavi, Corona

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28
Q

What are the + RNA N viruses?

A

Picrona, Calici

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29
Q

What are the four ways you can name RNA viruses by their physical and biochemical characteristics?

A

+RNA (N and E) -RNA (E) +/- RNA (Double Capsid) + RNA via DNA (E)

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30
Q

How can you name DNA viruses by their physical and biochemical characteristics?

A

DNA viruses can be broken into eneveloped and naked capsids. They can then be further broken down into: enveloped-> pox, herepes, hepadna naked capsid-> polyoma, papilloma, adeno, parvo

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31
Q

What are the ways of classifying and naming viruses?

A

structure, biochemical characteristics, disease, means of transmission, tissue or organ (tropism)

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32
Q

What is the smallest DNA virus? What is the largest DNA virus?

A

Parvovirus Poxvirus

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33
Q

What is the smallest RNA virus? What is the largest RNA virus?

A

Picornavirus Paramyxovirus

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34
Q

What is on the surface of the capsid or envelope that will mediate the interaction of the virus with a target cell.

A

Viral attachent protein (VAP)

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35
Q

What do you call antibodies that attack the VAP proteins?

A

neutralizing antibodies

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36
Q

Is the capsid a rigid structure or a floppy structure?

A

rigid

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37
Q

Viruses with naked capsids are resistant to what?

A

Drying, acid, detergents

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38
Q

What does the viral envelope contain and how can we maintain this structure?

A

lipids, proteins, glycoproteins In aqueous solutions (therefore it is transmitted in body fluids)

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39
Q

Can capsids be helical (rods)?

A

yes!

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40
Q

How do you get a helical (rod) capsid?

A

self-assemble on the RNA genome- creating a ribonucleocapsid

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41
Q

Where do you find most helical capsids?

A

NEGATIVE-STRAND RNA VIRUSES

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42
Q

Other than helical, what other form can capsids be?

A

icosahedrons

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43
Q

What do icosahedrons capsids look like?

A

a sphere (assembled from symmetrical subunits)

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44
Q

Simple icosahedrons like picornaviruses are made up of (blank) capsomeres, each with fivefold symmetry (pentamer)

A

12

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45
Q

So what are capsomeres?

A

they are the individual units of a capsid. i.e capsomeres make up a capsid

46
Q

What is the viral envelop composed of?

A

lipids, proteins, and glycoproteins (cellular membrane)

47
Q

The envelope is formed from the (blank)

A

cellular membrane

48
Q

Most (blank) act as VAPs that bind to target cells to initate entry. VAPS that bind to red blood cells are (Blank)

A

glycoproteins hemagglutinins

49
Q

The glycoproteins can form the (blank) on viruses and are usually (blank)

A

spikes immunodominant

50
Q

T or F all of the negative strand RNA viruses are enveleoped

A

T

51
Q

(blank) is a negative strand RNA virus that contains a segmented genome

A

Influenza A (orthomyxovirus)

52
Q

What is the tegument layer?

A

layer situated between the envelope and nucleocapsid- Contains enzymes, and other ptoeins that facilitate viral infection.

53
Q

What all do the host cells provide for viral replication?

A

substrates, energy and some of the machinery :)

54
Q

What are the phases of viral replication?

A

virus must recognize target cell, attach and penetrate PM. Uncoat its genome into cytoplasm and deliver genome to nucleus (sometimes). Genome replication and viral macromolecular synthesis followed by viral assembly and release.

55
Q

What is latency

A

when extracellular infectious virus is not detected but viral genomes can be detected

56
Q

What determines which cells can be infected by a virus?

A

the binding of the VAP to receptors on the cell

57
Q

Viruses may bind to receptors on cell types of specific species only. What do you call this?

A

host range

58
Q

THe suceptible target cell defines the (blank)

A

tissue tropism

59
Q

VAPs are usualy specific (blank) of enveloped viruses.

A

glycoproteins

60
Q

The HA of influenza A virus binds to (blank) expressed on many different cells and has a broad host range and tissue tropism.

A

sialic acid receptors

61
Q

How do enveloped viruses get their genome into a cell?

A

they fuse their membrane with cellular membranes to deliver the nucleocapsid or genome into the cytoplasm

62
Q

How do most nonenveloped viruses enter the cell?

A

by receptor mediated endocytosis

63
Q

When will fusion proteins be active?

A

at neutral pH (plasma membrane-virus fusion) OR In acidic condition of an endosome following receptor mediated endocytosis

64
Q

Can a virus give its genome to a cell with its capsid and envelope?

A

NO, the capsid and envelope must be removed.

65
Q

Most DNA genomes are delivered to the (Blank), most RNA genomes remain in the (blank)

A

nucleus cytoplasm

66
Q

Most DNA viruses use the cells (blank) to make mRNA.

A

DNA-dependent host RNA pol II

67
Q

mRNA must acquire what 2 things?

A

3’ poly A tail and 5’ methylated cap

68
Q

Most RNA viruses replicate and produce (blank) in the (blank). Therefore the virus must encode the enzymes for (blank)

A

mRNA cytoplasm transcription

69
Q

Some complex DNA viruses encode their own (blank) to regulate the expression of viral genes.

A

transcription factors

70
Q

What delivers the DNA genome to the nucleus?

A

the nucleocapsid

71
Q

(blank) rely on the cells machinery and substrates for replication

A

small DNA viruses

72
Q

How do you get the icosahedral shape of the nucleocapsid of a DNA virus?

A

Capsid proteins migrate into the nucleus, assemble into icosahedral capsids and are filled with the DNA genome

73
Q

How do you get RNA virus replication?

A
  1. binds to cell surface 2. endocytosed, 3. envelope fuses with the endosome vesicle membrane to deliver the nucleocapsid to the cytoplasm. 3. The virion must carry a polymerase, which produces the 5 mRNAs and a full length (+) strand template. 4 Proteins translated, glycoprotein G is glycosylated in the ER processed through the Golgi and delivered to the cell membrane. Genome is replicated from the (+) RNA template and the N, L, NS proteins associate with the genome to form the nucleocapsid The matrix protein associates with the G protein modified membrane which is followed by assembly of the nucleocapsid. The virus buds from the cell in a bullet-shaped virion
74
Q

(blank and blank) constitute the RNA dependent RNA polymerase

A

L and NS proteins

75
Q

How do you get binding of viral mRNA to host ribosome?

A

5 cap structure of methylated guanosine mediats binding of mRNA to host ribosome

76
Q

Ribosomes bind to viral mRNA and may produce on large (blank) which needs to be cleaved by cellular or viral proteases.

A

polyprotein

77
Q

T or F viral mRNA is preferentially translated in many cases

A

T

78
Q

Viral mRNA is preferentially translated in many cases. Some viruses block cellular mRNA egress from the nucleus T or F

A

T

79
Q

Some viral proteins require post-translation modifications such as (blank) and (blank)

A

phosphoryation and glycosylation

80
Q

Viral glycoproteins are synthesize on (blank)

A

membrane-bound ribosomes

81
Q

What do viral glycoproteins need?

A

AA sequence to allow for insertion into R

82
Q

Where does viral DNA replication begin? What binds here?

A

at the origin viral replication factors

83
Q

What do large DNA viruses encode?

A

their own DNA polymerase which make more errors, creating mutations

84
Q

What are a good target for antiviral nucleotide analogs?

A

DNA polymerases created by large DNA viruses

85
Q

RNA viruses must encode a (blank) polymerase.

A

RNA-dependent RNA polymerase

86
Q

What viral RNA strand can initate infection?

A

(+)

87
Q

What does the positive (+) RNA strand do?

A

it acts as mRNA and binds to ribosomes and directs protein synthesis

88
Q

What viral RNA strand can initate infection?

A

(+)

89
Q

What creates (-) negative RNA strand?

A

RNA dependent RNA polymerase

90
Q

What does (-) strand RNA do?

A

(-) strand RNA will produce (+) strand RNA which will make mRNA

91
Q

(-) strand RNA viral genomes are the template for production of (blank), this (-) RNA is not infectious unless there is a polymerase is present

A

(+) mRNA

92
Q

RNA viral transcription and replication occurs in the cytoplasm. What is the one exception?

A

Influenza viruses

93
Q

Explain RNA virus replication

A
  1. virus binds to cell surface
  2. endocytosis of virus
  3. nucleocapsid is delivered to cytoplasm
  4. Virion polymerase will produce 5 mRNAs and a full length (+) strand
  5. Protein translated, glycoprotein G is glycosylated in the ER, processed through the golig and delivered to cell membrane
  6. Genome is replicated from the (+) RNA template and N,L,NS proteins assocate with the genome to form the nucleocapsid
  7. virus buds from cell in a bullet shaped virion
94
Q

(blank and blank) proteins constitute the RNA dependent RNA polymerase

A

L and NS proteins

95
Q

Where is glycoprotein G glycosylated, processed and deiivered to?

A

glycoprotein G is glycosylated in the ER processed through the Golgi and delivered to the cell membrane.

96
Q

What makes up the nucleocapsid?

A

the N, L, NS proteins associate with the genome to form the nucleocapsid

97
Q

What mediates binding of vira mRNA to host ribosomes?

A

oThe 5’ cap structure of methylated guanosine mediates binding of viral mRNA to host ribosomes

98
Q

oRibosomes bind to viral mRNA and may produce one large (blank) which needs to be cleaved by cellular or viral proteases

A

polyprotein

99
Q

oViral mRNA is preferentially translated in many cases. Some viruses block cellular mRNA egress from the nucleus. T or F

A

T!!!

100
Q

oSome viral proteins require post-translational modifications such as what?

A

phosphorylation and glycosylation

101
Q

o
oViral glycoproteins are synthesized on (blank) and have the amino acid sequences to allow for (i) insertion into the rough endoplasmic reticulum and (ii) N-linked glycosylation

A

membrane-bound ribosomes

102
Q

What happens when the concentration of viral structural components is too high?

A

oWhen the concentration of viral structural components is high enough in the cell then protein-protein, protein-nucleic acid, and protein –membrane interactions occur

103
Q

When does viral budding occur?

A

after association of the nucleocapsid with the intracellular portion of viral glycoproteins

104
Q

oMost RNA viruses bud from the (blank)

A

plasma membrane

105
Q 
=
oOther viruses (the ones that dont bud from plasma membrane) acquire there envelope by budding into the (blank and blank)
A

endoplasmic reticulum and Golgi apparatus

106
Q

Viruses can be released what three ways?

A

by (i) cell lysis, (ii) exocytosis, or (iii) budding from the plasma membrane

107
Q

oMutated viruses arise from wild-type, which may (i) not change the phenotype, (ii) be detrimental or (iii) enhance pathogenicity and produce drug resistance T or F?

A

T

108
Q

oMutations in essential genes are (blank) mutations

A

lethal

109
Q

(blank) mutants cause less serious disease

A

oAttenuated

110
Q

New virus strains can be produced by (blank) between viruses or the virus and the host (recombination)

A

intermolecular exchange

111
Q

Viruses with (blank) genomes (influenza) can shuffle there segments if more than one viral strain is present in one host cell (reassortment)

A

segmented

Block 6 Week 4 (9 decks)

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