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MICRO200A Final > Viruses > Flashcards

Viruses Flashcards

1
Q

Viruses evolved before or after LUCA?

A

Before

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2
Q

What two components do viruses contain?

A

Capsid and nucleic acid

Can have DNA or RNA

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3
Q

Naked virus

A

Capsid is on the outside

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4
Q

Enveloped virus

A

Lipid bilayer surrounding virus

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5
Q

Viral genome

A
  • DNA or RNA

- Single or double stranded

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6
Q

Which DNA classes are double stranded?

A

Class 1 and 7

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7
Q

Which DNA class uses host machinery?

A

Class 1

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8
Q

Which DNA class reverse transcribes RNA to DNA?

A

Class 7

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9
Q

Which class of DNA is single strand DNA plus?

A

Class 2

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10
Q

Which class of DNA is used directly as mRNA?

A

Class 4

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11
Q

Viral mRNA is always considered to be in the plus or minus configuration?

A

Plus

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12
Q

Baltimore classification system

A

Based on relationship of viral genome to its mRNA

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13
Q

dsDNA (+/-) virus

A

Class 1 & 7

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14
Q

ssDNA (+) virus

A

Class 2

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15
Q

dsRNA (+/-) virus

A

Class 3

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16
Q

ssRNA (+) virus

A

Class 4

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17
Q

ssRNA (-) virus

A

Class 5

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18
Q

ssRNA (+) retrovirus

A

Class 6

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19
Q

Virion structure size

A

0.02-0.3um

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20
Q

Capsid

A

Protects genetic material

  • Repeated arrangements
  • Aids in transfer between organisms
  • Composed of capsomeres
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21
Q

Smallest virus

A

poliovirus

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22
Q

First discovered cell

A

Theba X174

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23
Q

Icosahedral

A

20 triangular faces
12 vertices
3 Protein molecules per triangular face in simplest structure
Can be made with 180, 240 or 360 capsomer

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24
Q

Nucleocapsid

A

Capsid+nuclear material

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25
Q

Helical virus

A

Protein with helical nucleic acid (flexible or rigid)

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26
Q

Tobacco mosaic virus

A

Genetic material tightly associated with protein coat

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27
Q

Helical virions are limited by

A

Length

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28
Q

HIV, influenza virus and herpesvirus are examples of

A

Enveloped viruses

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29
Q

Viruses containing enzymes

A 
HIV (reverse transcriptase)
Influenza virus (replicase)
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30
Q

Virus to host interactions

A

Lipopolysaccharides can connect external proteins

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31
Q

Virus life cycle

A
  1. attachment (adsorption)
  2. penetration
  3. synthesis
  4. assembly and packaging
  5. release
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32
Q

Virus phases

A

Once virus is added, proteins need to be produced to take over host machinery and replication of nucleic acids so there aren’t many viable viruses.
Assembly and release after everything is made

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33
Q

If cells are lysed during the _____________ form, the virus will not be released

A

Eclipse

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34
Q

Counting viral particles

A

Electron microscope, almost impossible if virus isn’t purified

35
Q

Counting infectious units

A

Plaque assays using plaque forming units

36
Q

Downside to plaque assays

A

Cannot determine efficiency since viruses infect with very low accuracy

37
Q

Bacteriophage efficiency

A

~50%

38
Q

Animal infection efficiency

A

0.1%

39
Q

T4 Virus

A

Icosohedral head.
Tail lyososymes can break down peptidoglycan layer
-20 minutes for infection
-Creates sigma factors to attack a specific gene

40
Q

Lysogenic bacteriophage

A

Temperate, long term infection

  • Viral DNA integrated into host genome
  • Trigger event causes viral DNA to pass over onto lytic side
41
Q

Lambda phage

A

Lysogenic phage

42
Q

Transduction

A

Horizontal gene transfer mediated by virus

Uses enzymes to cut nuclear genetic material

43
Q

Lysogenic virus

A

Makes double stranded or is double stranded and inserts specific DNA sequences

44
Q

Specialised transduction

A

Site specific recombination, can accidentally pull host chromosomes

45
Q

Animal DNA viruses

A

Herpesvirus, poxvirus, adenovirus, picomavirus.

46
Q

Times of infection

A

Lytic infection, latent infection, persistent infection

47
Q

Retroviruses

A 
o	Contains reverse transcriptase
o	Gag: structural
o	Pol: important for replication
o	Env: envelope proteins
o	RNA gene, can be translated
48
Q

Protease

A

Cuts polypeptide into capsid protein

49
Q

Influenza

A

Acute infection

-Spread by direct contact or aerosols

50
Q

HIV/AIDs

A

Chronic infection

-Spread sexually or by blood products

51
Q

Herpes simplex

A

Latent infection, spread through direct contact

-Infectious virus produced intermittently

52
Q

Why is it hard to make antivirals?

A

Viruses use many host functions, need unique targets

  • Viral groups differ from each other
  • Drugs have to get into host cell to deal with viral replication
53
Q

Immune attack system

A

Makes antibodies

-T-cells kill virus infected cells

54
Q

Immune memory system

A

Basis for vaccination

55
Q

Vaccines with live attenuated viruses

A
  • Polio, smallpox
  • Non-infectious, engineered or lost its ability to infect hosts
  • Long lasting effects
56
Q

Recombinant live virus vaccine

A

Vaccinia virus+rabies gene

  • Add genes to virus that are deadly
  • Vaccinia infection but gain protection against rabies
57
Q

Temperature sensitive virus vaccine

A

Virus won’t grow at body temperature

58
Q

Killed virus vaccine

A

Attenuated virus

-Salk polio, and rabies for humans

59
Q

Why is it hard to make effective vaccines?

A
  • Unsure how immune system functions
  • High mutation rate in viruses
  • Viruses might infect young children
60
Q

Influenza vaccine

A

Typically predict what the influenza virus will do

61
Q

Vaccines that are administered to young children

A

Given after immune system is fully developed

-Rotavirus and measles

62
Q

When the disease is more severe in adults..

A

Vaccination can reduce frequency

polio and chicken pox

63
Q

Vaccines for rotavirus reduce symptoms T/F

A

T

64
Q

Booster vaccines

A

Reintroduce immune system to epitope

65
Q

Animal vaccinations

A

Have to be effective, fast and cheap

66
Q

Cancer

A

Integration of viral DNA into host and may bring new genes into cells (HPV)

67
Q

Measles

A

Class 5 virus (ss(-), need to be translated into plus before infection)

  • Highly infectious
  • Nasal discharge, rash, fever, cough
  • paramoxyvirus
68
Q

Rubella

A
  • SS(+) Class 4 (RNA directly translated)

- Can cause fetal abnormalities

69
Q

HPV

A
  • 25% all cancers in women due to HPV
  • Cervical and ovarian
  • Pap smear to detect
  • Shuts down 2 tumor suppressor pathways
70
Q

Chicken pox and shingles

A
  • Varicella-Zoster virus
  • Highly contagious
  • Hides in dorsal root ganglion
  • Systemic poplar rash
71
Q

Common cold

A

Rhinovirus
(ss+RNA virus)
-picorna virus group
-Phomites (survive on surfaces)

72
Q

Influenza

A

Single stranded negative sense segmented RNA genome

  • Enveloped virus
  • 8 RNA segments, replicated and packaged into virus
73
Q

Influenza A

A
  • Steals cap from host and puts into RNA

- Segmentation allows antigenic shift

74
Q

Hemagluttinin

A

-Sialic acid target, flips domains and causes cell and viral membranes to squeeze together

75
Q

Neuraminidase

A
  • Sialidase, cuts sialic acid to go infect new host.
  • Mediates release of virons from host membrane
  • Drug target
76
Q

H1N1, H3N8… etc.

A

Types of hemaglutinin and neurominidase

77
Q

Influenza reassortment

A

Human influenza and bird influenza typically combine via swine and create a new virus

78
Q

Spanish flu

A

Most deaths were secondary infections after spanish flu

  • H1N1 strain
  • Highest mortality rate is 20-40 year olds
79
Q

Hypothesis for why flu fatalities of spanish flu were 20-40 yr olds

A

 Using sequence analysis, can see what flu was circulating during the time, first it was all H1 and then the people who were largely effected H3
•Theory that if you are born and first susceptible to H1 you will be more protected against certain viruses

80
Q

Subunit Vaccine

A

Hepatitis B, HPV

81
Q

Humoral immune response

A

Antibodies

82
Q

Cell mediated immune response

A

Another kind of immune response

83
Q

DIVA

A

differentiating infected from vaccinated animals (trade barriers to endemic countries)

MICRO200A Final (8 decks)

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