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RUSVM Virology Spring17 > (Final) Virus replication > Flashcards

(Final) Virus replication Flashcards

1
Q

T/F: Viruses have the capability to multiply by division

A

FALSE

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2
Q

How does a virus replicate?

A

It must hijack the host cell and utilize their organelles to produce its proteins and nucleic acid

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3
Q

What is a permissive cell?

A

A cell in which a virus is able to replicate

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4
Q

What is a non-permissive cell?

A

Cells in which a factor or factors necessary for viral replication is not present OR one detrimental to viral reproduction IS present, but the appropriate receptors are missing

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5
Q

What is the MOI or Multiplicity of Infection?

A

Refers to the number of virions that are added per cell during infection

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6
Q

When does the latent period of viral replication occur?

A

After uncoating and lasts until just before the 1st appearance of EXTRACELLULAR NEW virus particle

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7
Q

When does the eclipse period of viral replication occur?

A

After uncoating and until just before the 1st appearance of INTRAcellular new virus particle

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8
Q

What comes first, the latent period or eclipse period in virus replication?

A

Eclipse period since it goes until new virus is seen within the host cell

Latent = until the appearance of EXTRAcellular new virus particles

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9
Q

What is the Burst Size?

A

Number of infectious virions released per average cell

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10
Q

What are the steps of virus replication?

A
  1. Attachment
  2. Penetration
  3. Uncoating
  4. Synthesis of viral components (nucleic acid and protein)
  5. Assembly and maturation
  6. Release in large numbers
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11
Q

T/F: Virus attachment to receptors on the host cell are not specific

A

FALSE

they are very specific like a lock and key** each virus has its own surface receptor or receptors on specific host cells

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12
Q

How can cells escape attachment from viruses?

A

If they lack the appropriate receptor for that virus

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13
Q

T/F: In some cases, binding to a cellular receptor is not sufficient for infection; an additional cell surface molecule or co receptor will be needed for entry

A

TRUE

Co-receptors help certain viruses attach to host cells

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14
Q

Can some viruses use more than one host cell receptor for attachment?

A

YES

Ex: HIV

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15
Q

What are the two methods naked viruses can penetrate host cells?

A
  1. receptor mediated endocytosis (most common)

2. Pore mediated penetration

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16
Q

What two methods do enveloped viruses use to penetrate host cells?

A
  1. Surface membrane fusion (pH independent fusion protein)

2. Receptor mediated endocytosis (have pH DEPENDENT fusion protein)

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17
Q

How does FIP virus penetrate host cells?

A

Antibody-mediated attachment protein and penetration

This is an uncommon method of entry for viruses

18
Q

What is a more specific method of endocytosis used to penetrate host cells by Non-enveloped viruses?

A

Clathrin-mediated endocytosis

19
Q

The process of injecting a viral genome into the host cytoplasm through creation of a pore in the host membrane is known as what? What viruses do this?

A

Pore mediated penetration

done by naked/non-enveloped viruses

20
Q

T/F: Surface membrane fusion of enveloped viruses to host cells uses a pH indepented fusion protein

A

TRUE

21
Q

How does an enveloped virus with a pH dependent fusion protein enter a host cell?

A

Receptor mediated endocytosis

uses an endosome to penetrate the cell

22
Q

What method does FIP virus used to infect host macrophages?

A

antibody mediated attachment and penetration

23
Q

The release of viral genome in the host cell is known as what?

A

Virus uncoating

**The virus can no longer be detected

24
Q

T/F: After uncoating, a virus is no longer detectable

A

TRUE

25
Q

Are virions still infectious after they have undergone uncoating?

A

NO. they lose infectivity

this is bc they have released their DNA/RNA

26
Q

What are the two objectives of the “parent” virus taking over the host cell machinery?

A
  1. Make multiple copies for new viral genome

2. Make viral proteins for capsid successful replication

27
Q

What is the function of Reverse transcriptase?

A

Conversion of viral RNA to cDNA during virus replication

and for double strand DNA viruses that require a single strand RNA intermediate

28
Q

T/F: A positive strand of DNA will synthesize a positive strand of DNA

A

FALSE

positive will synthesize negative and vice versa

29
Q

What modifications must viral mRNA under do to be recognized by host ribosomes?

A
  1. capping
  2. addition of a PolyA tail
  3. Splicing

These are essential for the processing of viral mRNA

30
Q

Addition of 7-methylguanosine to the 5 prime end of RNA is what process?

A

Capping

**5 prime end of the viral mRNA

31
Q

What end of the viral mRNA does the poly A tail get added to?

A

3 prime end

*addition of poly-A tail
second step

32
Q

What is splicing?

A

RNA splicing is a process that removed introns and joins exons in a primary transcript

33
Q

T/F: Assembly of virus genome and proteins into new virions follows a specific order

A

TRUE

34
Q

Where does the assembly process and maturation of new viruses take place?

A

Many options depending on the virus

Nucleus, cytoplasm, plasma/cell membrane (most enveloped viruses)

35
Q

How do naked viruses leave host cells?

A

LYSIS

36
Q

T/F: Naked viruses can leave the host cell via budding

A

FALSE

they are naked so budding would given them an envelope

37
Q

Enveloped viruses leave the host cell via what process?

A

Budding through the plasma membrane

38
Q

What types of viruses leave the host cell via EXOCYTOSIS?

A

Viruses that acquire their envelope via budding from the ER, goli, or nuclear membrane

39
Q

What enzyme do reoviruses use to integrate with the host DNA?

What enzyme do they require to synthesize RNA into DNA?

A

integrase = integration

Reverse transcriptase

40
Q

What are two ways viruses spread cell-to-cell?

A

Extracellular spread

Intercellular spread - results in rapid virus dissemination, evasion of the immune system, and persistent infections

Nuclear spread of virus genome- viral genome is integrated into the host cell genome and passed down to progeny cells

41
Q

What is the fastest method of virus cell to cell transfer?

A

Intercellular spread

42
Q

How are viruses spread via progeny cells?

A

Nuclear spread

RUSVM Virology Spring17 (23 decks)

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