viruses Flashcards
(91 cards)
1
Q
what is the relative size of viruses?
A
ranges from 20nm up to 300nm
2
Q
how can you see viruses
A
by an ECM only
3
Q
which different shapes can viruses have?
A
- rod-shaped
- filamentous
- spherical shaped
- complex shaped
- pleomorphic
4
Q
describe rod-shaped viruses
A
- unique shape
- looks like a ballot
5
Q
what is the approximate size of filamentous viruses
A
up to 1000nm -> 1um
6
Q
list a few characteristics of filamentous viruses and name an example
A
- very thin
- ECM necessary
- very unique for ebola
7
Q
which viruses are spherical shaped?
A
most of human viruses
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
9
Q
which viruses are complex-shaped ones
A
- only bacterial viruses
10
Q
describe pleomorphic viruses
A
- no strict geometrical shape
- acquire cell membrane which hides the real shape of virus
- most of viruses
11
Q
how are nucleic acids arranged in cubical (icosahedral) viruses
A
- dont interact tightly with capsid proteins
12
Q
name the types of virus symmetries
A
- cubical
- spiral
- complex
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
14
Q
what are complex virus symmetries
A
- attributed to bacterial viruses
- cubical and spiral
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
16
Q
how are proteins of the shell in a virion called?
A
- nucleocapsid
17
Q
what contain enveloped viruses
A
supercapsid
- derivate from host cell membrane
18
Q
what are spikes?
A
glycoproteins on the surface of the virus for attachment to different receptors
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
20
Q
how many pentamers are in a mature virion?
A
- 12
21
Q
how is the the genome of the influenza virus structured?
A
- segmented with RNA
22
Q
what are the layers of the influenza virus?
A
from outside: glycoproteins lipid bilayer Matrix protein polymerase nucleoprotein RNA
23
Q
name the glycoproteins of the influenza virus
A
- hemagglutinin
- neuraminidase
24
Q
how is hemagglutinin of influenza a virus structured
A
- attachment region
- fusion region
25
what is the function of hemagglutinin?
- can react very specifically with receptors of epithelial cells
- high specificity
26
what does the the viral genome consist of?
- either of DNA or RNA
27
how is the viral DNA structured?
- single or double stranded
| - linear or circular
28
viral RNA can be
- positive sense (+) like mRNA
- negative sense (-)
- double stranded (+/-)
- ambisense (containing + and - regions attached end to end)
- segmented → genes are separated → are very changeble
29
how can viruses be classified?
- structure
- biochemical characterisitcs
- disease
- means of transmission
- host cell (host range)
- tissue or organ (tropism)
30
how are viruses classified acc. to their structure
- size
- morphology
- nucleic acid
- DNA or RNA
31
biochemical characteristics of viruses are
structure and mode of replication
32
DNA viruses can be
- enveloped or non-enveloped
| - double or single stranded
33
name examples of enveloped, ds DNA viruses
- hepadna, herpes and pox
34
name examples of non-enveloped, ds DNA viruses
papova/adeno -> papilloma (HPV)
35
parvo is what kind of virus
- non-enveloped, ss DNA virus
36
RNA viruses can be classified into
- enveloped and non-eveloped
- +ss or -ss RNA
- ds or ss RNA
37
what are enveloped, +ss RNA viruses
- flavi/toga/corona
- retro (HIV, lenti, HTLV-1,2(leukemia)
- filo (ebola, Marburg)
38
what are enveloped, -ss RNA viruses
- ortho-/paramyxo (influenza A,B and measles, mumps, RSV)
39
What kind of virus is bunya virus?
- enveloped, -ss RNA virus
40
What kind of virus is the rota virus?
- non-enveloped, ds RNA
41
name examples of non-enveloped ss RNA viruses
- calici/astro (Norwalk winter vomiting disease)
| - Picorna (Rhinovirus (cold), Entero(polio), hepato and aphtho (foot and mouth)
42
where do enveloped viruses get their cell membrane from
- derivate from the host cell during the exiting of the cell
43
where can the supercapsid of enveloped viruses be maintained?
- only in liquids
44
how are enveloped viruses usually transmitted?
- throughout body liquids
45
what happens if en. viruses are dried?
- inactivated
| - sensitive to during, acids (stomach, bile)
46
how are non-enveloped viruses transmitted?
- by food and water or fecal oral way
47
why are non-enveloped viruses harder to kill
- resistant to drying, detergents, bile and other chemical factors
- survive for a long period of time
48
name the stages of viral replication
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
how do viruses recognize the target cell?
- specificity determined by spikes
50
how do viruses attach to the cell?
- interact with receptor of host cell
51
mode of penetration of enveloped viruses
- by fusion of cell membrane
| - endocytosis
52
mode of penetration of Nate viruses
- interaction and formation of endosome
| - penetration into cytoplasm
53
what happens during uncoating?
- capsid is dissolved in endosome due to action of proteases of host cell and acidic pH
- release of nucleic acids into cytoplasm
54
what happens during the first stage of macromolecular synthesis?
5.1. Early mRNA and nonstructural protein synthesis: genes for
enzymes and nucleic acid-binding proteins
55
where does the viral genome replicate ?
- in cytoplasm or in the nucleus (depends on species of virus)
56
which viruses mostly replicate in the nucleus and how does it work
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
what happens if firstly the RNA is transcribed into positive strand of viruses which replicate in the cytoplasm?
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
what happens during late mRNA and structural protein synthesis
- proteins that compose the capsid are structural proteins
59
where does post translational modification of proteins happen
- in ER or Golgi complex
60
why is post translational mod. of prot. necessary?
- interaction between viral proteins
61
what kind of process is the assembly of viruses
thermodynamic process → very specific → form capsid of virus → viral particles transported to cell membrane
62
budding of enveloped viruses acquire what
- cell membrane
| - buds are released from cell surface
63
how are Nate capsid viruses released?
accumulation of high amounts → rupture of cell membrane (death of cell) → release into the environment
64
how can viruses be cultivated?
- in cell line cultures
- embryonales chicken eggs
- lab animals
65
which type is mostly used for cultivation?
- cell line cultures (primary, diploid, tumor and immortalized)
66
how do viruses grow In primary cell line cultures
- by attaching to surfaces
- derivate by tripsinisation
- separation of single cells
67
which cells mostly form monolayers in primary cell line cultures
- adherent cells
68
what is the advantage of primary cell line cultures
- immorte can undergo senescence
69
diploid cell line cultures are derivate from?
- embryonic cells because they have a higher passage number
70
tumor cell line c. are derivate from ?
- from tumors
| - unlimited passage number
71
How are immortalized c.l.c. produced
by infecting of cells with oncogenic DNA viruses
72
what is a chemically defined medium?
- fetal bovined serum for better sterilization
73
where are embryonate chicken eggs mostly used?
- in pharmaceutical industry (influenza virus)
74
where can the cytopathologic effect of herpes simplex virus be observed?
- in cells that produce mono layers
75
what could cause the herpes virus?
- deformation and multinucleate cells
76
what is mostly used for the cultivation of viruses in embryonate c.eggs
- chorioallantoic membrane inoculation
| - can obtain liquid from cavity you infected
77
which lab animals could be used only
- mice, rats or monkeys
- only for reasearch
- not widely used
78
name the types of viral infections at the cellular level
- abortiere, cytolytic, persistent and transforming
79
which types result in positive virus production?-
cytolytic, productive (persistent) and RNA viruses (transforming)
80
which result in negative v. production?
- abortive, latent (persistent) and DNA viruses
81
what fate of cell occurs in transforming types?
immortalization
82
which viruses have no effect on the fate of cell
- abortive and latent
83
what fate of cell results from productive infections?
- senescence
84
what fate of cell results from cytolytic infections?
- death
85
what are human defenses against a viral infection
- very specific
- interferons
- high body temperature
- NK cells
- cyotoxic T lymphocytes
- virus
- antibodies
86
what is the function of interferons?
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
how is the state of the cell called during the production and usage of interferons?
- anti-viral state
88
what happens due to high body temp?
due to cytokines → destabilize virus structure and slow down replication of virus
89
name the function of NK cells
recognize virus in effected cells and can kill them precisely and induce apoptosis → always in body
90
when are cytotoxic t lymphocytes produced?
→ only produced when viral infection
91
when are antibodies active?
- only if the virus outside the cell e.g. in the blood
