Lecture 33. Virology I: Genetic Diversity Flashcards

1
Q

What are viruses ?

A

Infectious, obligate intracellular parasites

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2
Q

What are viruses surrounded by ?

A

Protein coat and or lipid membrane

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3
Q

What do viruses within a host cell use to synthesis progeny virus particles ?

A

Cellular machinery

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4
Q

Where do viruses infect and replicate ?

A

Within cells

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5
Q

Are viruses cells ?

A

No

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6
Q

Where are all viral genomes packaged ?

A

Inside particles that mediate their transmission from host to host

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7
Q

What does the viral genome contain ?

A

Information necessary to initiate and complete an infectious cycle within a susceptible, permissive cell

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8
Q

Where are all successful virus able to establish themselves in ?

A

A host population

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9
Q

Why do viruses establish themselves in host populations ?

A

So viral survival is ensured

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10
Q

Why are viruses a perfect model for the concept of “survival of the fittest” ?

A
  1. Viruses that are too successful and kill their hosts eliminate themselves
  2. Viruses that are too passive and their replication is impeded by their hosts’ defences may be eliminated
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11
Q

What are viruses made of ?

A
  1. Capsid
  2. Proteins
  3. Genome
  4. May contain an envelope
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12
Q

What is a capsid ?

A

A protein shell

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13
Q

What are capsids made from ?

A

Identical proteins

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14
Q

What proteins may be present in viruses ?

A
  1. Enzymes
  2. Ion channels
  3. Immune modulators
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15
Q

What is contained in the genome of a virus ?

A

RNA or DNA

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16
Q

What is the viruses envelope ?

A

A lipid membrane

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17
Q

What is the function of the envelope ?

A

Block entry for enzymes

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18
Q

What are some structure of the viron ?

A
  1. Helical
  2. Polyhedral
  3. Icosahedral
  4. Spherical
  5. Complex
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19
Q

Who developed the seven genome types ?

A

David Baltimore

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20
Q

What is the genome type in group I ?

A

Double stranded DNA

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21
Q

What is the genome type in group II ?

A

Single stranded DNA

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22
Q

What is the genome type in group III ?

A

Double stranded RNA

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23
Q

What is the genome type in group IV ?

A

Single stranded positive sense RNA

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24
Q

What is the genome type in group V ?

A

Single stranded negative sense RNA

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25
What is the genome type in group VI ?
Single stranded positive sense RNA reverse transcriptase
26
What is the genome type in group VII ?
Double stranded DNA reverse transcriptase
27
What can positive strand RNA do ?
Be translated into a protein immediately
28
What can a negative strand of RNA do ?
Cannot be translated therefore must be transcribed into positive sense mRNA before translation
29
What information is encoded within the virus genome ?
Gene products for: 1. Virus genome replication 2. Assembly and packaging of the genome 3. Regulation of the virus replication cycle 4. Modulation of host defences 5. Spread to other cells and hosts
30
What information is not contained within the virus genome ?
1. The genes necessary for complete protein synthesis | 2. No gene encoding proteins for energy production or membrane synthesis
31
What must viral genomes be processed into so it can be read by host ribosomes ?
mRNA
32
What does an acute infection of poliovirus cause ?
Poliomyelitis
33
What group is poliovirus in ?
Group 4
34
What shape is poliovirus ?
Icosohedral
35
How many capsid proteins does poliovirus have ?
4
36
What are the capsid proteins contained in poliovirus ?
1. VP1 2. VP2 3. VP3 4. VP4
37
When is the pH of poliovirus stable ?
When its acidic
38
How many copies of proteins in a capsid of poliovirus ?
60
39
Who does poliovirus infect ?
People
40
How is poliovirus transmitted ?
Aerosol or ingestion (faecal-oral route)
41
What are the primary infection sites of poliovirus ?
Lymphoid tissue of pharynx and gut
42
What is the secondary infection site of poliovirus ?
Central nervous system
43
What causes paralysis and muscle weakness in poliovirus ?
Lytic infection of neurons
44
Who does the influenza virus affect ?
Birds, people, pigs, horses
45
What group is influenza in ?
Group V
46
What is in the structure of influenza ?
1. Glycoproteins 2. Matrix protein (M1) 3. Matric ion channel (M2) 4. Lipid bilayer 5. Nucleocapsid protein 6. Nuclear export protein 7. RNA polymerase proteins
47
What are the two glycoproteins in influenza structure ?
1. Neuroaminidase (NA) | 2. Haemagglutinin (HA)
48
What are the 3 RNA polymerase proteins ?
1. PB1 2. PB2 3. PA
49
How is influenza transmitted ?
Respiratory droplets
50
What is the primary infection site of influenza ?
Upper respiratory tract
51
When are you infectious with influenza ?
One or two days before symptoms
52
What is HIV ?
The causative agent of acquired immune deficiency syndrome (AIDS)
53
What type of infection is HIV ?
Persistent
54
How did HIV enter humans ?
Likely from chimpanzees
55
What does HIV do ?
Gradually destroys immune cells
56
What group is HIV in ?
Group VI
57
What is in the structure of HIV ?
1. Envelope proteins (gp120) 2. Capsule proteins (p24) 3. Reverse transcriptase 4. Lipid bilayer
58
How can HIV be transmitted ?
1. Blood 2. Sex 3. Mother to child - before and during birth, breast milk
59
What is the primary infection of varicella zoster virus ?
Chickenpox
60
What type of infection is varicella zoster virus ?
Persistent
61
How is varicella zoster virus transmitted ?
Aerosols and direct contact with rash
62
When is varicella zoster virus infectious and how long does it remain infectious?
1-2 days before rash appears and lasts till all lesions have crusted over
63
Where does varicella zoster virus persist ?
Nerve ganglia
64
What is the reactivation of varicella zoster virus called ?
Shingles
65
What is the structure of varicella zoster virus ?
1. Envelope proteins 2. Tegument 3. Nucleocapsid
66
What group is varicella zoster virus in ?
Group I
67
What is natural reservoir for severe acute respiratory syndrome ?
Bats
68
What are the three zoonotic coronaviruses ?
1. 2002-2003 SARS-CoV 2. 2012+ MERS-CoV 3. 2019+ SARS-CoV-2
69
What group is coronavirus in ?
Group IV
70
What is in the structure of coronavirus ?
1. Spike glycoprotein 2. Nucleoprotein 3. Membrane protein 4. Envelope small membrane protein
71
How is SARS-CoV-2 transmitted ?
Respiratory droplet, aerosols, contaminated surfaces
72
When is SARS-CoV-2 infectious ?
2 days before symptoms
73
Where is the primary infection site of SARS-CoV-2 ?
Upper respiratory tract