Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Infectious Agents II > Exam 1: Viral Replication > Flashcards

Exam 1: Viral Replication Flashcards

1
Q

What is the site of replication for adenoviridae?

A

Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the site of replication for herpesviridae?

A

Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the site of replication for poxviridae?

A

Cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the site of replication for retroviridae?

A

Nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do most DNA viruses replicate?

A

In the cell nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where do most RNA viruses replicate?

A

Cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the exceptions to where replication occurs?

A

DNA viruses- poxviridae and African swine fever replicate in cytoplasm
RNA viruses- orthomyxoviridae, retroviridae, and some paramyxoviruses such as canine distemper virus replicate in the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the replication cycle?

A 
Attachment or adsorption
Penetration or uptake
Uncoating
Synthesis of viral nucleic acid and protein
Assembly/maturation
Release
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is transcription?

A

DNA becoming mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is translation?

A

mRNA becoming protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does virus attach to the cell surface?

A

Recognizes specific receptors on the cell surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What makes a cell not susceptible to the virus?

A

It does not have receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the methods of penetration for enveloped viruses?

A

Fusion

Endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is fusion?

A

Entry by fusing with the plasma membrane

Only enveloped viruses use this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is endocytosis?

A

Entry by endosomes at the cell surface

The viruses are taken up by invagination of clathrin-coated pits into endosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens as the endosomes become acidified during endocytosis?

A

The virus membrane fuses with the endosome membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the fusion of endosome and virion membranes result in?

A

Releasing internal components of the virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the method of penetration for non-enveloped viruses?

A

Viruses may cross the plasma membrane directly or may be taken up via clathrin-coated pits into endosomes
The virus directly crosses endosome membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What must occur before virus replication can begin?

A

Nucleic acid has to be sufficiently uncoated before virus replication can begin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What occurs once the nucleic acid is uncoated?

A

Infectious virus particles cannot be recovered from the cell

This is the start of the eclipse phase, which lasts until new infectious virions are made

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the final stage of the assembly pathway go through for most viruses?

A

A set of structural transitions and/or biochemical modifications that transform recursor particles into infectious particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are many enveloped viruses released by?

A

Budding from plasma membrane of the host cells

23
Q

What are structural proteins?

A

All proteins in a mature virus particle even if they make no contribution to the morphology or rigidity of the virion

24
Q

What are non-structural proteins?

A

Viral proteins found in the cell but not packaged into the virion

25
Q

What is the cytopathic effect (CPE)?

A

Morphological changes in the host cells caused by viruses

26
Q

What does CPE consist of?

A

Cell rounding, disorientation, swelling or shrinking, death, detachment from the surface

27
Q

What does CPE depend on?

A

The virus and the cells on which it is grown

28
Q

What happens the more a virus passes or adapts in host cells?

A

The more virulent the virus becomes to the host

29
Q

What is primary culture?

A

The first in vitro cultures of cells taken directly from the organs

30
Q

What is cell-line?

A

A cell line that can be subcultured and grow continuously

31
Q

Describe viral genomes

A

Continuously changing
When viral infections occurs, viral particles replicates to produce millions of progeny. Errors in copying the nucleic acid inevitably occur
The nature of the viral genome plays an important role

32
Q

Describe segmented genomes

A

Usually transcribed to produce monocistronic mRNAs, which allows various proteins to be produced in different amounts rather than a constant ratio

33
Q

Describe non-segmented genomes

A

Tend to produce polycistronic mRNA, which is translated to form a polyprotein processed by proteolytic cleavage to form the mature gene products

34
Q

Are DNA or RNA viruses more stable?

A

DNA viruses

35
Q

What is proof reading ability?

A

An error correction mechanism in DNA virus host cell for DNA repair, but not for RNA

36
Q

What is the mutation rate for DNA viruses?

A

10^-8 to 10^-11 base per cycle

37
Q

What is the mutation rate for RNA viruses?

A

10^-3 to 10^-4 base per cycle

38
Q

Do all mutants persist in the virus population?

A

No

39
Q

What happens because of the redundancy of the genetic code?

A

Many mutations have no effect on viral protein or functionsq

40
Q

What is a point mutation?

A

One base is replaced by another or insertion/deletion of a base

41
Q

What is recombination?

A

Exchange of genetic information between two genomes

42
Q

When and where does reassortment occur?

A

If a virus has a segmented genome and if 2 variants of the virus infect a single cell
Only occurs in segmented RNA viruses

43
Q

What does multiplicity reactivation apply to?

A

A cell infected with 2 or more viruses of the same strain, each has a different mutated gene

44
Q

What makes a virus defective?

A

It lacks the full complement of genes necessary for a complete infectious cycle

45
Q

What is a helper virus?

A

A second virus that provides the defective virus with the missing functions

46
Q

What are examples of viruses that need a helper virus?

A

Retroviruses need related viruses

Hepatitis delta virus (RNA virus) needs hepatitis virus (DNA virus)

47
Q

What is phenotpying mixing?

A

When 2 different viruses infect a cell, progeny viruses may contain coat components of both parents
No alteration of genetic material
Life cycle of envelope-defective retroviruses

48
Q

What does a pseudotype have?

A

Genome of the defective parental virus but the envelope glycoproteins of the helper virus

49
Q

What are the envelope antigens that subtypes of influenza A virus are based on?

A

Hemagglutinin: H1 to H16
Neuraminidase: N1 to N9

50
Q

What is antigenic drift?

A

Point mutations

51
Q

What is antigenic shift?

A

Genetic reassortment and generate a new subtype

52
Q

Describe the Avian Influenza (AI) incident in Pennsylvania

A

In April 1983 an AI virus (H5N2) caused less than 10% of mortality in chickens
In October 1983, a change occurred in H5N2 virulence, mortality rate rose over 80%
The change in virulence had been due to a small umber of point mutations (genetic drift)

53
Q

What was the impact of high pathogenic AI in Pennsylvania?

A

Slaughter of millions of chickens

Cost more than $60 million

54
Q

What are the major cases of antigenic shifts resulting from reassortment of genome segments?

A

1997 (first case) H5N1 bird flu

2009-2010 H1N1 swine flu

Infectious Agents II (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions