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Microbiology pt.1 > viruses > Flashcards

viruses Flashcards

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1
Q

what is the relative size of viruses?

A

ranges from 20nm up to 300nm

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2
Q

how can you see viruses

A

by an ECM only

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3
Q

which different shapes can viruses have?

A
  • rod-shaped
  • filamentous
  • spherical shaped
  • complex shaped
  • pleomorphic
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4
Q

describe rod-shaped viruses

A
  • unique shape

- looks like a ballot

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5
Q

what is the approximate size of filamentous viruses

A

up to 1000nm -> 1um

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6
Q

list a few characteristics of filamentous viruses and name an example

A
  • very thin
  • ECM necessary
  • very unique for ebola
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7
Q

which viruses are spherical shaped?

A

most of human viruses

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8
Q

name the parts of complex-shaped viruses

A
  • head with nucleic acids

- tail with collar, tail sheath, plate and tail fibers for attaching

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9
Q

which viruses are complex-shaped ones

A
  • only bacterial viruses
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10
Q

describe pleomorphic viruses

A
  • no strict geometrical shape
  • acquire cell membrane which hides the real shape of virus
  • most of viruses
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11
Q

how are nucleic acids arranged in cubical (icosahedral) viruses

A
  • dont interact tightly with capsid proteins
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12
Q

name the types of virus symmetries

A
  • cubical
  • spiral
  • complex
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13
Q

how are capsid proteins arranged in spiral (helical) viruses

A
  • interact with nucleic acids repeating strands of nucleic acids
  • acquire shape of rods
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14
Q

what are complex virus symmetries

A
  • attributed to bacterial viruses

- cubical and spiral

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15
Q

what is inside the capsid of a virus (virion)

A
  • nucleic acids (DNA OR RNA) interact with capsid proteins

- shell of virus called capsid

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16
Q

how are proteins of the shell in a virion called?

A
  • nucleocapsid
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17
Q

what contain enveloped viruses

A

supercapsid

- derivate from host cell membrane

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18
Q

what are spikes?

A

glycoproteins on the surface of the virus for attachment to different receptors

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19
Q

how is the capsid of an icosahedral virus (picornavirus) formed?

A
  • made of proteins which interact and form bigger structures like capsomeres
  • form mature virion with nucleic acids inside
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20
Q

how many pentamers are in a mature virion?

A
  • 12
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21
Q

how is the the genome of the influenza virus structured?

A
  • segmented with RNA
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22
Q

what are the layers of the influenza virus?

A 
from outside:
glycoproteins
lipid bilayer
Matrix protein
polymerase
nucleoprotein
RNA
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23
Q

name the glycoproteins of the influenza virus

A
  • hemagglutinin

- neuraminidase

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24
Q

how is hemagglutinin of influenza a virus structured

A
  • attachment region

- fusion region

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25
Q

what is the function of hemagglutinin?

A
  • can react very specifically with receptors of epithelial cells
  • high specificity
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26
Q

what does the the viral genome consist of?

A
  • either of DNA or RNA
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27
Q

how is the viral DNA structured?

A
  • single or double stranded

- linear or circular

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28
Q

viral RNA can be

A
  • positive sense (+) like mRNA
  • negative sense (-)
  • double stranded (+/-)
  • ambisense (containing + and - regions attached end to end)
  • segmented → genes are separated → are very changeble
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29
Q

how can viruses be classified?

A
  • structure
  • biochemical characterisitcs
  • disease
  • means of transmission
  • host cell (host range)
  • tissue or organ (tropism)
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30
Q

how are viruses classified acc. to their structure

A
  • size
  • morphology
  • nucleic acid
  • DNA or RNA
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31
Q

biochemical characteristics of viruses are

A

structure and mode of replication

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32
Q

DNA viruses can be

A
  • enveloped or non-enveloped

- double or single stranded

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33
Q

name examples of enveloped, ds DNA viruses

A
  • hepadna, herpes and pox
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34
Q

name examples of non-enveloped, ds DNA viruses

A

papova/adeno -> papilloma (HPV)

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35
Q

parvo is what kind of virus

A
  • non-enveloped, ss DNA virus
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36
Q

RNA viruses can be classified into

A
  • enveloped and non-eveloped
  • +ss or -ss RNA
  • ds or ss RNA
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37
Q

what are enveloped, +ss RNA viruses

A
  • flavi/toga/corona
  • retro (HIV, lenti, HTLV-1,2(leukemia)
  • filo (ebola, Marburg)
38
Q

what are enveloped, -ss RNA viruses

A
  • ortho-/paramyxo (influenza A,B and measles, mumps, RSV)
39
Q

What kind of virus is bunya virus?

A
  • enveloped, -ss RNA virus
40
Q

What kind of virus is the rota virus?

A
  • non-enveloped, ds RNA
41
Q

name examples of non-enveloped ss RNA viruses

A
  • calici/astro (Norwalk winter vomiting disease)

- Picorna (Rhinovirus (cold), Entero(polio), hepato and aphtho (foot and mouth)

42
Q

where do enveloped viruses get their cell membrane from

A
  • derivate from the host cell during the exiting of the cell
43
Q

where can the supercapsid of enveloped viruses be maintained?

A
  • only in liquids
44
Q

how are enveloped viruses usually transmitted?

A
  • throughout body liquids
45
Q

what happens if en. viruses are dried?

A
  • inactivated

- sensitive to during, acids (stomach, bile)

46
Q

how are non-enveloped viruses transmitted?

A
  • by food and water or fecal oral way
47
Q

why are non-enveloped viruses harder to kill

A
  • resistant to drying, detergents, bile and other chemical factors
  • survive for a long period of time
48
Q

name the stages of viral replication

A
  1. Recognition of the target cell
  2. Attachment
  3. penetration
  4. uncoating
  5. macromolecular synthesis
  6. assembly of virus
  7. budding of enveloped virus
  8. release of virus
49
Q

how do viruses recognize the target cell?

A
  • specificity determined by spikes
50
Q

how do viruses attach to the cell?

A
  • interact with receptor of host cell
51
Q

mode of penetration of enveloped viruses

A
  • by fusion of cell membrane

- endocytosis

52
Q

mode of penetration of Nate viruses

A
  • interaction and formation of endosome

- penetration into cytoplasm

53
Q

what happens during uncoating?

A
  • capsid is dissolved in endosome due to action of proteases of host cell and acidic pH
  • release of nucleic acids into cytoplasm
54
Q

what happens during the first stage of macromolecular synthesis?

A

5.1.Early mRNA and nonstructural protein synthesis: genes for
enzymes and nucleic acid-binding proteins

55
Q

where does the viral genome replicate ?

A
  • in cytoplasm or in the nucleus (depends on species of virus)
56
Q

which viruses mostly replicate in the nucleus and how does it work

A

e. g. most of DNA viruses → nucleic acids are transported to nucleus because they use host cell polymerases in order to synthesize the complementary strands
- other viruses incl. influenza also in nucleus

57
Q

what happens if firstly the RNA is transcribed into positive strand of viruses which replicate in the cytoplasm?

A

if it is first transcribed into positive strand ( retro virus like HIV) → 2 RNA molecules → after infectíng cells RNA transcribed into DNA and integrated into host cell chromosome and can be activated → RNA are produced instead of DNA

58
Q

what happens during late mRNA and structural protein synthesis

A
  • proteins that compose the capsid are structural proteins
59
Q

where does post translational modification of proteins happen

A
  • in ER or Golgi complex
60
Q

why is post translational mod. of prot. necessary?

A
  • interaction between viral proteins
61
Q

what kind of process is the assembly of viruses

A

thermodynamic process → very specific → form capsid of virus → viral particles transported to cell membrane

62
Q

budding of enveloped viruses acquire what

A
  • cell membrane

- buds are released from cell surface

63
Q

how are Nate capsid viruses released?

A

accumulation of high amounts → rupture of cell membrane (death of cell) → release into the environment

64
Q

how can viruses be cultivated?

A
  • in cell line cultures
  • embryonales chicken eggs
  • lab animals
65
Q

which type is mostly used for cultivation?

A
  • cell line cultures (primary, diploid, tumor and immortalized)
66
Q

how do viruses grow In primary cell line cultures

A
  • by attaching to surfaces
  • derivate by tripsinisation
  • separation of single cells
67
Q

which cells mostly form monolayers in primary cell line cultures

A
  • adherent cells
68
Q

what is the advantage of primary cell line cultures

A
  • immorte can undergo senescence
69
Q

diploid cell line cultures are derivate from?

A
  • embryonic cells because they have a higher passage number
70
Q

tumor cell line c. are derivate from ?

A
  • from tumors

- unlimited passage number

71
Q

How are immortalized c.l.c. produced

A

by infecting of cells with oncogenic DNA viruses

72
Q

what is a chemically defined medium?

A
  • fetal bovined serum for better sterilization
73
Q

where are embryonate chicken eggs mostly used?

A
  • in pharmaceutical industry (influenza virus)
74
Q

where can the cytopathologic effect of herpes simplex virus be observed?

A
  • in cells that produce mono layers
75
Q

what could cause the herpes virus?

A
  • deformation and multinucleate cells
76
Q

what is mostly used for the cultivation of viruses in embryonate c.eggs

A
  • chorioallantoic membrane inoculation

- can obtain liquid from cavity you infected

77
Q

which lab animals could be used only

A
  • mice, rats or monkeys
  • only for reasearch
  • not widely used
78
Q

name the types of viral infections at the cellular level

A
  • abortiere, cytolytic, persistent and transforming
79
Q

which types result in positive virus production?-

A

cytolytic, productive (persistent) and RNA viruses (transforming)

80
Q

which result in negative v. production?

A
  • abortive, latent (persistent) and DNA viruses
81
Q

what fate of cell occurs in transforming types?

A

immortalization

82
Q

which viruses have no effect on the fate of cell

A
  • abortive and latent
83
Q

what fate of cell results from productive infections?

A
  • senescence
84
Q

what fate of cell results from cytolytic infections?

A
  • death
85
Q

what are human defenses against a viral infection

A
  • very specific
  • interferons
  • high body temperature
  • NK cells
  • cyotoxic T lymphocytes
  • virus
  • antibodies
86
Q

what is the function of interferons?

A

cell itself has its own immune reaction by producing interferons → released → attach to receptors on other cells → interaction causes production of antiviral proteins (enzymes like ribonucleases capable to break down viral nucleic acids)

87
Q

how is the state of the cell called during the production and usage of interferons?

A
  • anti-viral state
88
Q

what happens due to high body temp?

A

due to cytokines → destabilize virus structure and slow down replication of virus

89
Q

name the function of NK cells

A

recognize virus in effected cells and can kill them precisely and induce apoptosis → always in body

90
Q

when are cytotoxic t lymphocytes produced?

A

→ only produced when viral infection

91
Q

when are antibodies active?

A
  • only if the virus outside the cell e.g. in the blood

Microbiology pt.1 (10 decks)

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