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RUSVM Virology Summer 2017 > Virus Replication > Flashcards

Virus Replication Flashcards

1
Q

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

A

FALSE!

Viruses do NOT have the genetic capability to multiply by division.

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2
Q

A virus hijacks and utilizes the host cell machinery to produce what?

A

To produce its proteins and nucleic acid for the next generation of virus

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3
Q

What does the process of virus replication in a host cell resemble?

A

An assembly line

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4
Q

Permissive Cell

A

A cell in which a virus is able to replicate.

i.e. the machinery SUPPORTS REPLICATION of the virus

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5
Q

Non- Permissive Cell

A

Cell in which a factor or factors necessary to viral reproduction is not present or one detrimental to viral reproduction is present.
i.e. ABSENCE OF APPROPRIATE RECEPTORS

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6
Q

_______ refers to the number of virions that are added per cell during infection.

A

MOI (Multiplicity of Infection)

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7
Q

What steps are included in the One-Step Virus Growth Curve?

A

1) Adsorption
2) Eclipse Period
3) Latent Period
4) Burst Size

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8
Q

During this period, the virus attaches to and enters the cells, and the titer of free virus in the medium may actually decline.

A

Adsorption

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9
Q

________ period: After uncoating and till just before 1st appearance of INTRACELLULAR new virus particle.

A

Eclipse Period

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10
Q

________ period: After uncoating and till just before 1st appearance of EXTRACELLULAR new virus particle.

A

Latent Period

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11
Q

The time before new infectious virus appears in the medium

A

Latent Period

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12
Q

During this phase no extracellular virions are detected.

A

Latent Period

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13
Q

Burst Size

A

The number of infectious virions released per average cell

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14
Q

The 6 Steps of Virus Replication in order

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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15
Q

T/F: Virus attachement to a receptor(s) on host cell is not specific.

A

FALSE!!!

Virus attachment to a receptor(s) on host cell is VERY SPECIFIC (like a lock and key)

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16
Q

T/F: Each virus has its own specific receptor or receptors on specific host cells.

A

True

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17
Q

What is the attachment on host cell surface mediated by?

A

Interactions between the virus and complimentary receptor on the host cell surface.

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18
Q

T/F: Cells that lack the appropriate receptor escape being infected by the virus.

A

True
(note: if the host cell does not have the specific receptor for the virus, the virus will not be able to attach to the host cell; therefore the host cell escapes being infected by the virus)

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19
Q

T/F: In all cases, binding to a cell receptor is sufficient for infection.

A

FASLE!!!
In SOME cases, binding to a cell receptor is NOT sufficient for infection. – in some cases an additional cell surface molecule, or CO-RECEPTOR, is required for entry.

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20
Q

What is an example of a virus that may use more than one host cell receptor?

A

HIV

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21
Q

What are the different types of Penetration?

A

1) Endocytosis
2) Surface Fusion
3) Pore- Mediated Penetration
4) Antibody- Mediated Penetration

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22
Q

Penetration types of Noneveloped/ Naked Viruses

A

1) Receptor mediated endocytosis (Commonly Seen)

2) Pore mediated penetration (In some naked viruses)

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23
Q

Penetration types of Enveloped Viruses

A

1) Surface membrane fusion (have pH INDEPENDENT fusion protein)
2) Receptor mediated endocytosis (have pH DEPENDENT fusion protein)

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24
Q

What is an example of receptor mediated endocytosis that is commonly seen in nonenveloped/ naked viruses?

A

Cathrin- mediated endocytosis

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25
Q

What is the name of the penetration type when some non-enveloped viruses inject their genome into the host cytoplasm through creation of a pore in the host membrane.

A

Pore- mediated endocytosis

26
Q

Which penetration type of enveloped viruses have a pH INDEPENDENT fusion protein?

A

Surface membrane fusion

27
Q

Which penetration type of enveloped viruses have a pH DEPENDENT fusion protein?

A

Receptor mediated endocytosis

28
Q

What is the name of the penetration for enveloped viruses in which fusion of virus envelope with host cell membrane occurs directly on the surface of the host cell?

A

Surface membrane fusion

29
Q

What is the name of the penetration for enveloped viruses in which fusion of virus membrane with host endosomal membrane release viral genome?

A

Receptor mediated endocytosis

30
Q

In this method of penetration for enveloped viruses, the fusion proteins require low pH to get activated, which is achieved in endosome and thus facilitate virus envelope fusion with endosomal membrane.

A

Receptor mediated endocytosis

31
Q

FIPV uses an uncommon penetration method of entry, which method does it use?

A

Antibody- mediated attachment and penetration

32
Q

What is the name of the step in virus replication where the viral genome is released in the host cell?

A

Uncoating

33
Q

T/F: During uncoating the virion can no longer be detected, but the virion can still be infective.

A

FALSE!

During uncaring the virion can no longer be detected, and their is LOSS OF INFECTIVITY OF THE VIRIONS!

34
Q

During synthesis of viral components ( nucleic acid and protein) what are the functions of the parent virus?

A

Function 1: Multiple copies for new viruses (children/ progeny)
Function2: Viral proteins for capsid and successful replication

35
Q

Reverse Transcriptase converts viral ___A.___ to ___B.____ during virus replication

A

A. RNA

B. cDNA

36
Q

T/F: Viral DNA must conform to the requirements of host cell translation system during the Processing of Primary RNA Transcript.

A

FALSE!

Viral mRNA!!! must conform to the requirements of host cell translation system.

37
Q

A series of modifications occur, known as processing of primary RNA Transcript/ Pre-RNA. What are these series of modifications?

A
  1. Capping
  2. Addition of Poly A tail
  3. Splicing
38
Q

T/F: During capping there is an addition of 7- methylguanosinn to the 5’ end of RNA

A

True

39
Q

T/F: During the Addition of a Poly A tail there is a stretch of adenylate residues added to the 3’ end.

A

True

40
Q

RNA splicing is a process that removes _____A.____ and joins ____B.____ in a primary transcript.

A

A. Introns

B. Exons

41
Q

_______ is the portion of gene that codes for amino acids.

A

Exon

42
Q

_______ is the portion of a gene that does NOT code for amino acids.

A

Intron

43
Q 
After processing, mRNAs are translated in the: 
A. Nucleus 
B. E.R.
C. Cytoplasm
D. Mitochondria
A

C. Cytoplasm

44
Q 
Viral mRNAs produced in the \_\_\_\_\_\_\_\_\_ must be exported to the cytoplasm. 
A. Nucleus 
B. Rough E.R.
C. Smooth E.R.
D. Mitochondria
A

A. Nucleus

45
Q

What are the 2 types of Viral mRNA?

A
  1. Monocistronic

2. Polycistronic

46
Q

Monocistronic is mRNA that encodes _____ polypeptides.

A

one

47
Q

Polycistronic is mRNA that encodes ______ polypeptides.

A

Several

48
Q

Where can assembly and maturation take place?

A
  1. Nucleus
  2. Cytoplasm
  3. Plasma/ Cell Membrane (Most Enveloped Viruses)
49
Q 
Assembly and maturation of MOST enveloped viruses takes place: 
A. Plasma/ Cell Membrane
B. Nucleus 
C. Cytoplasm
D. Mitochondria
A

A. Plasma/ Cell Membrane

50
Q

T/F: Assembly of virus genome and proteins into new virions can occur in any order.

A

FALSE!!

Assembly of virus genome and proteins into new virions follows a SPECIFIC ORDER!

51
Q

T/F: Naked Virions cause lysis of the host cell. They can then exit the host cell by budding because they lack an envelope.

A

FALSE!!

Naked Virions cause lysis of the host cell. They can NOT exit the host cell by budding because they lack an envelope.

52
Q

Enveloped virions are released in large numbers, by exiting the host cell via _______.

A

Budding

53
Q 
Viruses acquire their envelope by budding from all of the following when leaving the host cell by exocytosis, EXCEPT: 
A. ER
B. Nuclear/ nucleus membrane 
C. Mitochondria membrane 
D. Golgi apparatus
A

C. Mitochondria membrane.

ER; Nuclear/ nucleus membrane and the Golgi apparatus

54
Q

T/F: Viruses mature by budding through the membrane of the Golgi apparatus or ER during exocytosis.

A

True

55
Q

Vesicles containing the virus migrate to the plasma membrane and are released by __________.

A

Exocytosis

56
Q

Replication of retroviruses can occur via ____A.____ and ____B.______.

A

A. Reverse Transcriptase

B. Integrase

57
Q

_________ synthesizes RNA into DNA.

A

Reverse Transcriptase

58
Q

_________ integrates viral DNA into the host genome.

A

Integrase

59
Q

How can viruses spread from cell to cell?

A
  1. Extracellular Spread
  2. Intercellular Spread
  3. Nuclear Spread of Virus Genome
60
Q

This type of cell to cell spread results in rapid virus dissemination, evasion of immune system and persistent infections.

A

Intercellular Spread

RUSVM Virology Summer 2017 (23 decks)

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