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Principles: Microbiology > Virology > Flashcards

Virology Flashcards

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Biology 101 flashcards
1
Q

Give the basic structural components of a virus

A
  • Nucleic acid
  • Protein coat
  • Protein spikes
  • Lipid envelope (only in some viruses)
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2
Q

Describe the genome of a virus

A
  • very small

- either RNA or DNA, never both

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3
Q

Describe the protein coat of a virus

A
  • Encases the nucleic acid
  • Made of repeating subunits
  • A simple geometric structure
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4
Q

Describe the source of lipid coat some viruses have

A

It is derived from the host cell

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5
Q

Give 2 examples of possible symmetry shown by viruses

A

Icosahedral

Helical

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6
Q

Describe the features of an icosahedral symmetrical virus

A
  • 20 sided spheroid

- 3 subunit types (apex, edge, flat)

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7
Q

Describe the features of an helically symmetrical virus

A
  • 1 single repeating unit

- 1 repeating unit, so only 1 gene required

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8
Q

List the phases of a viral life-cycle

A
  • Attachment
  • Entry
  • Uncoating
  • Nucleic acid & protein synthesis
  • Assembly
  • Release
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9
Q

Describe how a virus attaches to a host cell

A

Protein spike acts as a ligand and binds to a cell surface receptor

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10
Q

Why do viral infections often stay localised?

A

As during the viruses protein spike is a specific ligand to a certain cell surface receptor type

Only some cells express that receptor. Virus can’t spread to cells without it

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11
Q

Describe how a virus enters a host cell once attached

A

Viral and cell membranes fuse

OR

Endocytosis - The virus binding to the receptor triggers endocytosis

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12
Q

Describe viral uncoating

A

The virus sheds its protein coat once inside the cell

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13
Q

Describe how viral protein synthesis occurs in a host cell

A
  • Viral nucleic acid is used as instructions to produce viral proteins
  • Host ribosomes used
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14
Q

Describe viral assembly inside host cells

A
  • Nucleic acid and proteins are packaged together

- Form crystals of assembling viruses (visible in some cells as inclusions)

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15
Q

Give the 2 types if viral release from a host cell

A

Budding and lysis

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16
Q

Describe viral release by budding

A

The virus encases itself in an lipid envelope (cell membrane) to leave the cell

17
Q

What kinds of virus often release via budding

A

Viruses that have a lipid envelope

18
Q

Describe viral release by lysis

A
  • Viruses accumulate in the host cell

- Eventually the viruses lyse the cell and are released

19
Q

List possible targets for antiviral grugs

A
  • Viral enzymes (nucleic acid synthesis)
  • Viral enzymes (viral protein synthesis)
  • Attachment
  • Entry
  • Uncoating
  • Release
20
Q

Name a class of antivirals that affect the immune system

A

Immune adjuvants

21
Q

Describe the purpose of immune adjuvants

A

To affect to immune system to better allow it to deal with the viral infection

22
Q

What is rational drug design?

A
  • Molecular analysis of viral targets to design a molecule that may inhibit its function
  • Instead of blindly testing

(doesn’t work for bacteria as they are to complex)

23
Q

Where might antiviral resistance seen?

A

After long periods of treatment

Especially if immunocompromised

24
Q

Describe how viral infections are damaging to a host organism

A
  • Cell death by lysis or hijacking of cell machinery

- Cell death by immune cells

25
Q

Are viruses implicated in causing cancers?

A

Yes

26
Q

Describe the 2 main components of an antiviral adaptive immune response

A
  • Cytotoxic T lymphocytes

- Neutralising antibodies (IgG, IgM)

27
Q

Describe the role of cytotoxic T lymphocytes in an antiviral immune response

A
  • Detect viral proteins of infected cells

- Induce apoptosis in infected cell

28
Q

Describe the role of neutralising antibodies in an antiviral immune response

A
  • Bind to viruses (aggregation)

- Prevent viruses properly infecting cells

29
Q

Give an example of innate immunity in an antiviral response

A

Double stranded RNA induces the expression of interferons

30
Q

What are interferons?

A

Signalling proteins released by virally infected cells

Warn other cells to increase their anti-viral defences

31
Q

Describe the 2 types of viral persistence?

A

1) Intermittent - Virus becomes inactive. No active replication. Can reactivate later
2) Constant - Remain constantly active

32
Q

How are viral infections confirmed in the lab?

A
  • Antiviral antibodies detected

- Virus itself detected

33
Q

Give examples of test used to detect a virus

A
  • PCR

- Antigen detection

34
Q

How are new infections differentiated from old ones?

A
  • Detection of IgM

- High level of IgG

Principles: Microbiology (6 decks)

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