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MICR2000 > M4 - Virology > Flashcards

M4 - Virology Flashcards

1
Q

Characteristics of a virus

A

• Intracellular parasite
– Cannot replicate outside a living cell
– Large inert macromolecules
• Possess only one kind of nucleic acid: DNA or RNA
• Limited amount of genetic material: ~3-200 genes
• cannot code for energy production due to not enough genetic info
• no ribosomes
• not grow but replicate to increase the number
• Viral nucleic acid and viral protein synthesis occur separately: come together during maturation.
• Lipids and carbohydrates are acquired from the host cell (not coded for by viral genome)

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2
Q

Composition of a virus

A

a nucleic acid genome (RNA or DNA) + protein

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3
Q

Virus proteins are coded by …

A

viral genome or from host

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4
Q

particle (virion)

A

病毒顆粒（病毒粒子）

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5
Q

penetration

A

滲透

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6
Q

polymerases

A

聚合酶

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7
Q

helicases

A

解旋酶

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8
Q

proteases

A

蛋白酶

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9
Q

Structural proteins

A

part of the virus particle (virion) and wrapping around the core of viruses

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10
Q

Functions of structural proteins

A

cell attachment and penetration & protection

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11
Q

Location & functions of Non-structural proteins

A

most not found in virion

– replication(polymerases,helicases)
– virus assembly and release (proteases)

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12
Q

Nucleocapsid

A

核衣殼 = capsid(protein shell surrounding viral genome) + genome

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13
Q

Capsid

A

衣殼
protein shell surrounding viral genome

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14
Q

capsomer

A

衣殼粒a kind of structural proteins
Many capsomers make capsids

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15
Q

Icosahedral

A

二十面體

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16
Q

spherical

A

球體

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17
Q

Helical Nucleocapsids

A

螺旋核衣殼

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18
Q

Rod-shaped

A

桿狀

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19
Q

naked viruses

A

Viruses composed only of nucleic acid and protein

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20
Q

enveloped viruses

A

Viruses that acquire an outer layer of membrane from the host during replication

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21
Q

Feature of naked virus

A
  • very stable in the environment
  • nucleic acid “encased” in protein
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22
Q

Feature of Enveloped viruses

A

• more fragile 脆弱
• more susceptible to inactivation because of lipid content

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23
Q

naked helical viruses only found in…

A

plant and bacterial viruses

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24
Q

Complex Viruses

A

Large viruses with complex structure

25
Q

How do viruses acquire an envelope?

A

The virus acquires the envelope as it matures and buds through the cell membrane

26
Q

What factors determine the structure of a virus

A
  1. Types of viruses
  2. Type of Nucleic Acid: DNA or RNA
  3. Capsid protein: The composition and arrangement of the capsid protein affect the appearance of the virus.
  4. Have envelope or not
27
Q

Stages of replication

A
  1. absorption/attachment
  2. Penetration
  3. uncoating
  4. replication
  5. release/maturation
28
Q

Virus attachment sites

A

Enveloped viruses: spike or peplomers
Naked viruses: anywhere

29
Q

spike

A

尖峰

30
Q

peplomers

A

聚合物

31
Q

The way of Attachment

A

– physical complementarity between virus and receptor
– specific interaction (most viruses can only infect some cell types)

32
Q

PENETRATION

A

內吞作用
virus is engulfed into cytoplasmic vacuole

33
Q

The ways of penetration

A
  1. Endocytosis
  2. Membrane fusion: only enveloped viruses
  3. Direct entry: some naked viruses
34
Q

The ways of penetration for naked viruses

A
  1. direct entry: The nucleocapsid undergoes molecular rearrangement allowing viral genome to enter the cell.
  2. Exosomes: Naked viruses are excreted from infected cells in exosomes and enter new cells in membrane-bound particles
35
Q

Un-coating

A

allows release of the genome into the cytoplasm - Often spontaneous自發性的

36
Q

Synthesis of viral protein and nucleic acid for DNA viruses

A

Replicate in the cell nucleus

because all DNA replicative enzymes are found in the nucleus

37
Q

Synthesis of viral protein and nucleic acid for RNA viruses

A

Generally replicating in the cytoplasm

RNA viruses code for replicative enzymes (proteins) but need polyribosomes to translate them from mRNA

38
Q

Replication of negative (-) strand genome

A
  1. Negative strand genomic RNA released into the cytoplasm
  2. The replicase enzymes are brought into the cell as part of the virion
  3. Negative (-) strand RNA must first serve as a template to make complementary positive (+) strand RNA to translate viral proteins.
39
Q

Virus maturation and release

A

simple viruses: self-assembly
complex viruses: require various stages

40
Q

Maturation and release of viruses for naked viruses

A

Mainly, accumulate累積 in cell and release progeny子代 virus suddenly through cell bursted破裂

but some progeny viruses are secreted gradually from intact cell in exosomes

41
Q

exosomes

A

外泌體

42
Q

progeny

A

子代

43
Q

Maturation and release of viruses for Enveloped viruses

A

bud through cell membrane – released gradually

44
Q

Three types of targets for Antiviral Agents

A

Protein synthesis
Cellular enzymes for DNA replication (for DNA viruses)
Cellular energy to drive synthesis and enzyme reactions

45
Q

necrosis

A

壞死：cell death by rupture of cell during virus release

46
Q

apoptosis

A

細胞凋亡cell commits suicide in response to infection

47
Q

Immunopathology

A

免疫病理學

48
Q

What causes the symptoms of virus infection?

A

1) Damage to cells due to virus replication: necrosis壞死, apoptosis細胞凋零 ＆ infected cell loses function
2) Damage due to the host response to infection: Immunopathology, fever, inflammation

49
Q

pathogenesis

A

發病機制

50
Q

HOST factors which modify viral pathogenesis

A
  • Age
  • Genetics
  • Metabolic state
  • “Altered” immune responses: genetically determined, consequence of infection & iatrogenically (therapeutically)
51
Q

iatrogenically

A

醫源性

52
Q

Routes of virus entry

A
  • skin
  • respiratory tract
  • gastrointestinal tract
  • genitourinary tract
  • conjunctiva
53
Q

gastrointestinal tract

A

胃腸道

54
Q

genitourinary tract

A

泌尿生殖道

55
Q

conjunctiva

A

結膜

56
Q

how virus get into host through skin

A
  • mechanical trauma
  • by injection
  • by the bite of an infected sth
57
Q

how virus get into host through Genitourinary Tract

A

Tears or abrasions擦傷

58
Q

abrasions

A

擦傷

59
Q
A

MICR2000 (5 decks)

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