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Microbiology Midterm 2 > Lecture 16: Virology > Flashcards

Lecture 16: Virology Flashcards

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Biology 101 flashcards
1
Q

What is a virus

A

A package of genetic information (can be DNA or RNA) protected by a protein shell for delivery into a host cell to be expressed and replicated

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2
Q

Who intially described virus

A

Eward Jenner in 1798

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3
Q

What are the four characteristics which differentiate viruses from other micro-organisms

A
  1. nucleic acid (either have DNA or RNA) not both
  2. Lack of nuclear membrane and external cell wall
  3. Very small genomes, so only codes for a very small number of proteins
  4. Do not possess intracellular systems (like ribosomes), they are obligate intracellular parasites, meaning that they depend on a host cell and use their machinery to replicate
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4
Q

What is the largest bacterial cell

A

smallpox virus (200 nm x 300 nm), need an electron microscope to see

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5
Q

What does the tobacco mosaic virus infect

A

plants

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6
Q

When were smallpox pustules found

A

found on 3000 year old mummy of Pharaoh Ramses

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7
Q

What virus was found in 1400 BC

A

Paralytic poliomyelitis which causes leg deformities

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8
Q

What viral diseases were found over the past 1000 years

A

Smallpox and measlses

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9
Q

What viral diseases were found over the past 100 years

A

Spanish Influenza, HIV

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10
Q

What viral disease made human life expectancy decrease

A

Spanish influenza

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11
Q

What viral diseases were found over the past 10 years

A

West Nile, SARS, MERS, Avian Flu, HINI pandemic flu, Ebola, SARS-CoV2

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12
Q

How are viruses named/classified

A

Usually based on data available at the time of discovery

Based on;
Disease
Cyto-pathology (what they cause)
Site of isolation
Places or people that discovered them
Biochemical features

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13
Q

What viruses were named based on the disease they are associated with

A

HIV, Measles

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14
Q

What viruses were named based on their cyto-pathology they cause

A

Cytomegalovirus

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15
Q

What viruses were named based on their site of isolation

A

Adenovirus, Enterovirus, Phinovirus

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16
Q

What viruses were named based on the people or places that discovered them

A

Epstein-Barr virus, West Nile Fever

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17
Q

What viruses were named based on biochemical features

A

Retrovirus

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18
Q

What is viral classification is based upon

A

Size and shape

Enveloped or naked

Nucleic acid compostion (RNA or DNA)

Genome organization

Antigenic differences (Ex. H1N1)

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19
Q

What are capsomere

A

Smallest protein subunit of the capsid

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20
Q

What is a capsid

A

Capsomers assemble to form viral capsid - surrounds the viral genome

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21
Q

Nucleocapsid

A

Capsid + genomic nucleic acids (DNA or RNA) virus found within

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22
Q

What is the typically shape of a capsid

A

symmetrical

23
Q

What type of virus has a cubic/icosehedral shape

A

Herpes virus

Probs the most common type of shape

24
Q

What virus has a helical shape

A

influenza virus

25
Q

What is a complex virus

A

doesn’t fit into the other two shapes

ex., Pox virus

26
Q

What are surface structures in viruses

A

Surface projections and glycoproteins bind host receptors to allow entry

27
Q

What is the envelope of virus

A

lipid layer surrounding some viruses, it is derived from the host cell membrane

28
Q

Is a virus with or without an envelope easier to kill

A

Enveloped virus is easier to kill, because the virus needs the envelope to survive

29
Q

A ______ virus is stable in the environment

A

Non-enveloped virus

30
Q

A ____ virus is labile in the environment

A

Enveloped virus

31
Q

What does it mean if the virus is stable

A

Resist desiccation, acids, detergents or heat

Ex. Viruses usually infect the gastrointestinal tract (norovirus and hepatitis A)

Transmitted easily via hands and fomites

32
Q

What does it mean if the virus is labile

A

damaged by drying (dies very quickly), acid, detergents or heat (herpes viruses, HIV, HCV, HBV, influenza)

Must stay moist - transmitted in droplet or body fluids

Do not usually infect the gastroinesteinal tract, usually blood-borne or respiratory

33
Q

What is the composition of RNA viruses

A

RNA single stranded
- positive polarity
- negative polarity (need ti reversily translate to mRNA)

RNA double stranded one segmented

34
Q

What is the composition of DNA viruses

A

Single stranded or double stranded

35
Q

What viruses are acquired via direct personal contact

A

Herpes viruses: skin -> skin
HIV: need exposure to blood
Influenza: close association likely not from a formit

36
Q

What viruses are acquired via airborne spread

A

Chickenpox, measles

37
Q

What viruses are acquired via fomites

A

enteroviruses, noroviruses

38
Q

What viruses are acquired via vectors

A

West Nile from a misquoto

39
Q

What viruses are acquired via vertical transmission

A

mom –> fetus

HIV, Herpes simplex, cytomegalovirus, rubella (german measles)

40
Q

What viruses are acquired via enteral

A

(food/waterborne)

Hepatitis A, gastroenteritis viruses

41
Q

What are the steps of the virus life cycle at the cellular level

A
  1. attachment
  2. penetration
  3. uncoating
  4. transcription
  5. translation
  6. genome replication
  7. assembly
  8. release
42
Q

What are the steps of infection at an organism level

A

This is the host interaction

  1. Entry into host
  2. Primary replication
  3. Spread
  4. Cell and tissue tropism
  5. Secondary replication
  6. Cell injury or persistence
  7. Host immune response
43
Q

What are the consequences of virus-cell interactions

A

Viral proliferation and cell lysis

Latent infection (non replicating virus)

Persistent infection (ongoing viral replication, few or no symptoms)

ocogenesis (cellular proferation)

No apparent disease

44
Q

What viruses can result in Viral proliferation and cell lysis

A

cold sores (HSV), gential herpes (H1S1 or HSV2), chickenpox

45
Q

What viruses can result in latent infection (non replicating virus)

A

Herpes viruses, human papilloma viruses

46
Q

what viruses can result in persistent infection (ongoing viral replication, few or no symptoms)

A

Hepatitis C and B, HIV

Tissue injury may be induced by the virus or an immune response to th eviral infection

47
Q

what virus can result in oncogenesis

A

human papilloma virus, EMV

48
Q

What virus has no apparent disease

A

Hepatitis G

49
Q

What are the different ways of diagnosing viral infections

A

Clinical faetures

Laboratory diagnosis:
- Detection of viral antigens in tissues/in serum

Antibody testing through virus isolation
- rising IgG, IgM, very high titer IgG , any IgG)

DNA or RNA amplification:
in tissue sections, from tissues, in serum and fluids

50
Q

What is a syndromic approach

A

when viruses can be found in multiple places

ex. herpes

51
Q

What are prions

A

“proteninceous infectious partciles”
An infectious agent composed of protein

52
Q

What are characteritics of prions

A

a prion dose not self replicate, it induces existing protein to take on the “rogue” form

Very highly resistant (exterme temperatures, both dry and wet as well as radition)

Causes severe neurological diseases in host of mammalian species

53
Q

What are examples of the spongifoem encephalopathies in the human form

A

Human forms from prions are
Creutzfeldt-Jacob Disease (takes decades to become disease)
New varient of the disease can come on within 5 years
Kuru (neurological disease caused from eating brains

54
Q

What are examples of the spongifoem encephalopathies in the animal form

A

Bovine Spongiform Encephalopathy, AKA: Mad Cow Disease

Can potentially be transmitted to humans

Microbiology Midterm 2 (15 decks)

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