Unit 1 Flashcards
(135 cards)
1
Q
Define zoonosis.
A
Zoonosis: infectious diseases transmitted from animals to humans
-Introduction to Virology
2
Q
True or False:
Viruses are non-living entities.
A
True.
-Introduction to Virology
3
Q
What is a virion?
A
A virion is an extracellular, infectious, complete virus particle that consists of a RNA or DNA core, protein coat, and sometimes an external envelope.
-Introduction to Virology
4
Q
What is a virus?
A
A virus is a general term used to describe any aspect of the infectious agent and includes: the virion, an inactivated virus particle, or viral nucleic acid and protein inside the infected host cell.
-Introduction to Virology
5
Q
What is a viroid?
A
A viroid is an infectious agent of certain plant diseases that is smaller than any of the known viruses. A viroid particle only consists of an extremely small circular RNA molecule and lacks the protein coat of a virus.
-Introduction to Virology
6
Q
True or False:
A viroid is a type of virus.
A
False.
-Introduction to Virology
7
Q
Who is produced the first smallpox vaccination?
A
Edward Jenner inoculated some “cowpox matter” repeatedly into the arms of healthy individuals who became immune and did not succumb to smallpox - and thus invented the vaccination.
-Introduction to Virology
8
Q
Who is responsible for the recovery of two boys that were bitten by rabid dogs and recovered from the disease?
A
Louis Pasteur injected dried, potassium hydroxide treated, infected rabbit brain material in two boys bitten by rabid dogs and both of them recovered.
-Introduction to Virology
9
Q
In 1884, Charles Chamberland invented the Chamberland filter. What did the filter remove from solution and what remained in the filtrate?
A
The Chamberland filter has pores that are smaller than bacteria, thus removing the bacteria [and larger particles/cells] from the solution leaving viral particles in the filtrate.
-Introduction to Virology
10
Q
Who coined the term “virus” to refer to the infectious substance found in finely filtered solution?
A
Martin Beijerinck called this filtered, infectious substance a “virus” and this discovery is considered to be the beginning of virology.
-Introduction to Virology
11
Q
Who discovered the cause of foot-and-mouth (hoof-and-mouth) disease?
A
In 1898, Friedrich Loeffler and Paul Frosh passed the first animal virus through a filter [similar to a Chamberland filter] and discovered the cause of foot-and-mouth disease.
-Introduction to Virology
12
Q
Who is the “Conqueror of Yellow Fever”? How did he earn that title?
A
Dr. Walter Reed became internationally known for his discovery that yellow fever is spread through mosquitoes.
-Introduction to Virology
13
Q
Who isolated the first tumor-causing animal virus and what is the name of the virus he isolated?
A
Peyton Rous isolated the first tumor-causing animal virus in 1911 at the Rockefeller Institute. He won the Nobel Prize in 1966 for his discovery of the Rous sarcoma virus.
-Introduction to Virology
14
Q
What was the first virus cultivated in eggs? Who reportedly propagated this virus in eggs?
A
In 1931, Woodruff, Goodpasture, and Burnet reported propagating fowlpox virus in an embryonated hen’s egg.
-Introduction to Virology
15
Q
A pathogen or disease-causing agent that has been completely eliminated from a defined geographic region is said to be _________.
A
Eradication of an infectious disease involves complete elimination of the pathogen or the disease-causing agent from a defined geographic region.
-Introduction to Virology
16
Q
_________ has been eradicated in people.
_________ is on the verge of eradication in people.
_________ appears to be the only virus eradicated from animals.
A
Smallpox has been eradicated in people.
Polio virus is on the verge of eradication in people.
Rinderpest appears to be the only virus eradicated from animals.
-Introduction to Virology
17
Q
What family of viruses typically have an outer and inner capsid?
A
Reoviridae viruses typically have an inner and an outer membrane.
-Structure and Chemical Composition of Viruses
18
Q
What are the two smallest viruses?
A
The smallest viruses are porcine circovirus type 1 (17 nm in diameter) and parvoviruses (18 nm in diameter).
-Structure and Chemical Composition of Viruses
19
Q
What is the largest known virus and what does it infect?
A
The pandoravirus (400 nm in diameter) is the largest known virus and it infects protozoa. -Structure and Chemical Composition of Viruses
20
Q
What is the largest known virus of mammals and birds?
A
The poxvirus (200 nm in diameter, 300 nm in length) is the largest virus that infects mammals and birds. -Structure and Chemical Composition of Viruses
21
Q
What is pleomorphism?
A
Pleomorphism: the ability of some viruses to alter their shape or size
-Structure and Chemical Composition of Viruses
22
Q
What shape is ebola virus?
A
Ebola virus is filament-shaped.
-Structure and Chemical Composition of Viruses
23
Q
What shape is rabies virus?
A
Rabies virus is bullet-shaped.
-Structure and Chemical Composition of Viruses
24
Q
What shape is a bacteriophage?
A
A bacteriophage is tadpole-shaped.
-Structure and Chemical Composition of Viruses
25
What shape is tobacco mosaic virus?
Tobacco mosaic virus is rod-shaped.
| -Structure and Chemical Composition of Viruses
26
What shape is poxvirus?
Poxvirus is brick-shaped.
| -Structure and Chemical Composition of Viruses
27
What shape is rotavirus?
Rotavirus is spherical.
| -Structure and Chemical Composition of Viruses
28
True or False:
| Biological materials require negative staining when performing electron microscopy (EM).
True.
| -Structure and Chemical Composition of Viruses
29
What is the advantage of cryo-electron microscopy (cryo-EM) over standard electron microscopy (EM)?
Cryo-electron microscopy (cryo-EM) allows the observation of biological specimens in their native environment, meaning they do not mean to be stained or fixed in any way.
-Structure and Chemical Composition of Viruses
30
True or False:
| All viruses contain nucleic acid.
True. The nucleic acid composes the viral genome, which can either be DNA or RNA.
-Structure and Chemical Composition of Viruses
31
What is the term used for the virus particle's protein coat?
The capsid is a protein coat that surrounds the DNA or RNA of the virus particle.
-Structure and Chemical Composition of Viruses
32
True or False:
| Some virions lack a capsid.
False. All virions possess a capsid. All viroids lack a capsid.
-Structure and Chemical Composition of Viruses
33
Which has a greater association between the capsomeres and the nucleic acids, a nucleocapsid with polyhedral or helical symmetry?
In the nucleocapsids with helical symmetry, the capsomeres and nucleic acid are wound together to form a helical or spiral tube.
-Structure and Chemical Composition of Viruses
34
True or False:
It is more common to find a polyhedral virus lacking nucleic acid than it is to find a helical virus lacking nucleic acid.
True. Because of the interactions between the nucleic acid and capsid protein, incomplete virions (empty helical particles) cannot form. Therefore, you are very unlikely to find a helical virus without a nucleic acid associated with it.
-Structure and Chemical Composition of Viruses
35
What major morphological difference is commonly observed between animal viruses with helical symmetry and plant viruses with helical symmetry?
In all animal viruses, the helical nucleocapsid is enclosed with a lipoprotein envelope, while naked helical nucleocapsids are common among plant viruses.
-Structure and Chemical Composition of Viruses
36
Describe the shape and symmetry of the tobacco mosaic virus. Is it enveloped or naked?
The tobacco mosaic virus is rod-shaped, naked helical virus.
| -Structure and Chemical Composition of Viruses
37
True or False:
A virus particle does not possess standard cellular organelles - such as a Golgi apparatus, endoplasmic reticulum - which prevents them from being able to replicate outside of a host cell. However, viruses do have mitochondria, because every cell needs energy.
False. A virus particle does not possess standard cellular organelles - such as a Golgi apparatus, endoplasmic reticulum, or mitochondria - which prevents them from being able to replicate and produce energy outside of a host cell.
-Introduction to Virology
38
What is a viral capsid composed of?
The capsomeres are the basic subunit proteins in the capsid of a virus.
-Structure and Chemical Composition of Viruses
39
What are the viral proteins present on the virus envelope and where are they located?
The envelope of a virus possess 2 viral proteins: the glycoproteins - located on the outside of the envelope - and the matrix protein - located on the inside of the envelope, outside of the nucleocapsid.
-Structure and Chemical Composition of Viruses
40
What are hemagglutinin (HA) and neuraminidase (NP) and what are their functions?
Hemagglutinin (HA) and neuraminidase (NP) are examples of viral external glycoproteins. Hemagglutinin (HA) aids in the virus binding to a host cell, fusion of the envelope and the host cell membrane, hemagglutination, and is antigenic. Neuraminidase (NP) aids in the release of viral progeny from a host cell and is antigenic.
-Structure and Chemical Composition of Viruses
41
What is a penton?
A penton is a pentagonal capsomere located at the vertices of icosahedral viral capsids.
-Structure and Chemical Composition of Viruses
42
What is a hexon?
A hexon is a hexagonal capsomere composing the facets of icosahedral viral capsids.
-Structure and Chemical Composition of Viruses
43
What is a facet?
A facet is the term used to describe the equilateral triangular faces of icosahedral viral capsids.
-Structure and Chemical Composition of Viruses
44
How many vertices does an icosahedral viral capsid have?
An icosahedral viral capsid has 12 vertices (corners).
| -Structure and Chemical Composition of Viruses
45
How many facets does an icosahedral viral capsid have?
An icosahedral viral capsid has 20 facets.
| -Structure and Chemical Composition of Viruses
46
How many pentons does an icosahedral viral capsid have?
An icosahedral viral capsid has one penton located at each of the 12 vertices (12 pentons).
-Structure and Chemical Composition of Viruses
47
How many hexons does an icosahedral viral capsid have?
The number of hexons on an icosahedral viral capsid varies with the virus group.
-Structure and Chemical Composition of Viruses
48
What is another name for icosahedral symmetry?
Cubic symmetry is synonymous with icosahedral symmetry.
| -Structure and Chemical Composition of Viruses
49
What is the triangulation number (T-number)?
The triangulation number, or T-number, describes the relation between the number of pentons and hexons of the icosahedron.
-Structure and Chemical Composition of Viruses
50
What does a small vs. large T-number indicate?
The smaller the triangulation number (T-number) is, the less hexons are present relative to pentons on the icosahedral viral capsid. The larger the triangulation number (T-number) is, the more hexons are present relative to pentons on the icosahedral viral capsid.
-Structure and Chemical Composition of Viruses
51
Write the formula used to calculate the T-number.
The formula used to calculate the triangulation number (T-number) is:
T = (h^2) + (h x k) + (k^2)
-Structure and Chemical Composition of Viruses
52
What virus possesses the simplest icosahedral capsid?
Parvovirus has the simplest icosahedral capsid (T=1).
| -Structure and Chemical Composition of Viruses
53
What is complex symmetry?
Complex symmetry describes virions that are composed of several parts, each with separate shapes and symmetries.
-Structure and Chemical Composition of Viruses
54
Pox viruses and bacterial viruses exhibit what type of symmetry?
Pox viruses and bacterial viruses (bacteriophages) exhibit complex symmetry.
-Structure and Chemical Composition of Viruses
55
What are the five main functions of the viral capsid?
The functions of the viral capsid include:
1) Protection the viral nucleic acid
2) Facilitate attachment of the virus to specific receptors on a susceptible host cell via receptor attachment proteins
3) Interacts with the host cell's membranes to form an envelope
4) Viral uncoating and transportation of the viral genome to the appropriate site within the host cell
5) Facilitates specific recognition and packaging of the nucleic acid genome
- Structure and Chemical Composition of Viruses
56
True or False:
| Most (+)ssRNA viruses uncoat and release their genome into the host cell's cytoplasm.
True.
| -Structure and Chemical Composition of Viruses
57
What two viruses utilize the capsid as the core of replication?
The capsid of reoviruses and retroviruses serve as the core of replication.
-Structure and Chemical Composition of Viruses
58
What are the functions of a viral envelope?
The viral envelope facilitates virus entry into the host cell and may also help the virus to adapt fast and evade the host immune system.
-Structure and Chemical Composition of Viruses
59
The viral envelope is acquired when the viral nucleocapsid buds through what types of host cell membranes?
The viral envelope is acquired when the viral nucleocapsid buds through either the host cell's cytoplasmic membrane, Golgi membrane, or nuclear membrane.
-Structure and Chemical Composition of Viruses
60
What determines where viral envelope budding will occur?
Viral envelope budding only occurs at the sites where the virus-specific proteins have been inserted into the host cell membrane.
-Structure and Chemical Composition of Viruses
61
What are the "spikes" seen on the virus surface?
The viral glycoproteins are often referred to as the spikes seen on the virus surface.
-Structure and Chemical Composition of Viruses
62
What are the two types of glycoproteins associated with a viral envelope?
There are two types of proteins associated with a viral envelope:
1) External glycoproteins
2) Channel proteins
- Structure and Chemical Composition of Viruses
63
What structure is responsible for modifying the internal environment of an enveloped virus?
The channel proteins are important in modifying the internal environment of an enveloped virus.
-Structure and Chemical Composition of Viruses
64
What are the two types of fusion proteins?
There are two types of fusion proteins:
1) pH dependent
2) pH independent
- Structure and Chemical Composition of Viruses
65
If an enveloped virus has pH independent fusion proteins, how does it release its nucleocapsid in the host cell?
An enveloped virus with pH independent fusion proteins will bind to specific receptors on a susceptible host cell, the viral envelope and host cell membrane fuse, and the virus releases its nucleocapsid into the host cytoplasm.
-Structure and Chemical Composition of Viruses
66
If an enveloped virus has pH dependent fusion proteins, where does it release its nucleocapsid in the host cell?
An enveloped virus with pH dependent fusion proteins will bind to specific receptors on a susceptible host cell, the virus and envelope are endocytosed into the host cell, the endosome pulls in hydrogen ions (H+) from the cytoplasm, decreasing the pH within the endosome, which triggers the viral envelope to fuse with the endosome, and release its nucleocapsid into the host cytoplasm.
-Structure and Chemical Composition of Viruses
67
True or False:
All viruses require aqueous or moist environments to be maintained because they are very sensitive to desiccation, heat, and alteration of pH.
False. Enveloped viruses require aqueous or moist environments to be maintained because they are very susceptible to desiccation, heat, and alteration of pH.
-Structure and Chemical Composition of Viruses
68
Describe the two ways in with viral DNA can be oriented/shaped.
Viral DNA can either be linear or circular.
| -Structure and Chemical Composition of Viruses
69
What gives circular viral DNA its shape?
The presence of histones give viral DNA a circular appearance.
-Structure and Chemical Composition of Viruses
70
Which type of RNA virus, positive-sense RNA or negative-sense RNA, has an infective genome?
An RNA virus with a positive-sense RNA genome is said to have an infectious genome.
-Structure and Chemical Composition of Viruses
71
Define monopartite.
Monopartite: non-segmented RNA genome of a virus
| -Structure and Chemical Composition of Viruses
72
Define multipartite.
Multipartite: segmented RNA genome of a virus
| -Structure and Chemical Composition of Viruses
73
What is the most common outcome of antigenic drift?
The most common outcome of antigenic drift is a silent mutation.
-Structure and Chemical Composition of Viruses
74
What is another name for antigenic drift?
Antigenic drift is also referred to as a point mutation.
| -Structure and Chemical Composition of Viruses
75
What are the 3 types of point mutations?
The 3 types of point mutations are:
1) Silent mutation
2) Nonsense mutation
3) Missense mutation
- Structure and Chemical Composition of Viruses
76
What is a silent mutation?
A silent mutation is a point mutation in the codon that generates the same amino acid that the original codon sequence would have produced.
Example:
Original DNA codon = TTC, RNA anticodon = AAG, amino acid = lysine (Lys)
Silent point mutation DNA codon = TTT, RNA anticodon= AAA, amino acid = lysine (Lys)
-Structure and Chemical Composition of Viruses
77
What is a nonsense mutation?
A nonsense mutation is a point mutation in the codon that generates a STOP codon.
Example:
Original DNA codon = TTC, RNA anticodon = AAG, amino acid = lysine (Lys)
Nonsense point mutation DNA codon = ATC, RNA anticodon= UAG, amino acid = NONE
-Structure and Chemical Composition of Viruses
78
What is a missense mutation?
A missense mutation is a point mutation in the codon that generates a different amino acid that the original codon sequence would have produced.
Example:
Original DNA codon = TTC, RNA anticodon = AAG, amino acid = lysine (Lys)
Missense point mutation DNA codon = TCC, RNA anticodon= AGG, amino acid = arginine (Arg)
-Structure and Chemical Composition of Viruses
79
What is genetic recombination?
Genetic recombination occurs when two viruses infect the same host cell, combine their DNA or RNA sequence for a gene on a single strand or segment, and produce progeny with the sequence for that gene containing part of the DNA or RNA of both of the viruses.
-Structure and Chemical Composition of Viruses
80
True or False:
| Genetic reassortment only occurs in RNA viruses.
True. Genetic reassortment only occurs between viruses with a segmented genome. RNA viruses can have segmented genomes, while DNA viruses cannot.
-Structure and Chemical Composition of Viruses
81
What is genetic reassortment?
Genetic reassortment occurs when two different strains of the same virus infect the same host cell, mix their RNA segments between progeny particles, and produce progeny with genes of either strain.
-Structure and Chemical Composition of Viruses
82
What two families of double-stranded DNA viruses have the simplest genomes?
Polyomaviridae and Papillomaviridae viruses have relatively simple, circular, super-coiled genomes containing 5-8 thousand base pairs (kilobase pair, kbp).
-Structure and Chemical Composition of Viruses
83
What subfamily of double stranded DNA viruses have the most complex genome?
Herpesvirinae have a complex, linear genome containing 125-235 thousand base pairs (kilobase pair, kbp).
-Structure and Chemical Composition of Viruses
84
How many base pairs do single-stranded DNA viral genomes have?
The single-stranded DNA viral genomes are either linear (Parvoviridae) or circular (Circoviridae and Anellovirus), with sizes ranging from 2.8-5 thousand base pairs (kilobase pair, kbp).
-Structure and Chemical Composition of Viruses
85
What type of virus has the smallest RNA genome?
The genome of Deltavirus contains less than 2 thousand base pairs (kilobase pair, kbp).
-Structure and Chemical Composition of Viruses
86
What family of viruses has the largest RNA genome?
The genome of Coronaviridae has more than 30 thousand base pairs (kilobase pair, kbp).
-Structure and Chemical Composition of Viruses
87
What percentage of the virion is viral proteins?
Viral proteins constitute up to 50%-70% if the virion.
| -Structure and Chemical Composition of Viruses
88
What are lysins?
Lysins are hydrolytic enzymes produced by bacteriophages to cleave the host's cell wall.
-Structure and Chemical Composition of Viruses
89
What is retroviral integrase (IN)?
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Retroviral integrase (IN) is an enzyme produced by retroviruses (i.e. HIV) that enables its genetic material to be integrated into the DNA of the infected host cell.
-Structure and Chemical Composition of Viruses
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90
What is reverse transcriptase (RT)?
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Reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from a RNA template.
-Structure and Chemical Composition of Viruses
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91
What are nucleic acid polymerases?
Nucleic acid polymerases are enzymes essential for replication of the viral genome.
-Structure and Chemical Composition of Viruses
92
What are neuraminidases?
Neuraminidases are enzymes that cleave glycosidic bonds, allowing the release of progeny viral particles from the infected host cell.
-Structure and Chemical Composition of Viruses
93
What are viral structural proteins?
Viral structural proteins are the proteins that form the viral capsid.
-Structure and Chemical Composition of Viruses
94
What are viral nonstructural proteins?
Viral nonstructural proteins are proteins encoded by a viral genome that are produced in the infected host cell, but are not packaged into the progeny virus particles. Some of these proteins may play roles within the infected cell during virus replication, regulate virus replication, or regulate virus assembly.
-Structure and Chemical Composition of Viruses
95
True or False:
| You are very unlikely to see viral nonstructural proteins in an extracellular virion.
True. Viral nonstructural proteins are produced in the infected host cell and are not packed into the newly generated virus particles. Viral nonstructural proteins are crucial for virus replication, which cannot occur outside of a susceptible host cell, so they are not necessary to package.
-Structure and Chemical Composition of Viruses
96
What is an incomplete virion?
An incomplete virion is a virion without nucleic acid (an empty capsid).
-Structure and Chemical Composition of Viruses
97
What is a defective virion?
A defective virion is a virus that cannot replicate because it lacks a full complement, or copy, of viral genes. Defective viral particles result from mutations or errors during the production or assembly of virions.
-Structure and Chemical Composition of Viruses
98
True or False:
| Defective virions can never replicate.
False. Replication of defective virions can occur during mixed infections with a helper virus. The helper virus can supplement the genetic deficiency and make the defective virus replicate progeny virions.
-Structure and Chemical Composition of Viruses
99
What is a defective interfering particle (DIP)?
A defective interfering particle (DIP) interferes with other congeneric, mature virions from entering the occupied host cell.
-Structure and Chemical Composition of Viruses
100
What is a pseudovirion?
A pseudovirion is a virus particle that contains a non-viral genome within the viral capsid, such as the host nucleic acid rather than the viral nucleic acid. Pseudovirions look the same as ordinary virions under an electron microscope, but pseudovirions do not replicate.
-Structure and Chemical Composition of Viruses
101
What is a pseudotype?
A pseudotype is produced when related viruses infect the same cell and their genomes get assembled with the other viral capsid.
-Structure and Chemical Composition of Viruses
102
Which is easier to sterilize: naked viral particles or enveloped viral particles?
Enveloped viral particles are easier to sterilize because they cannot survive for long periods of time outside of the host cell.
-Structure and Chemical Composition of Viruses
103
According to the Baltimore Classification System, what group does a double-stranded DNA (dsDNA) virus belong to?
According to the Baltimore Classification System, a double-stranded DNA (dsDNA) virus belongs to Group I.
-Classification of Viruses
104
According to the Baltimore Classification System, what group does a double-stranded DNA (dsDNA) virus that requires a RNA intermediate belong to?
According to the Baltimore Classification System, a double-stranded DNA (dsDNA) virus that requires a RNA intermediate belongs to Group VII.
-Classification of Viruses
105
According to the Baltimore Classification System, what group does a double-stranded RNA (dsRNA) virus belong to?
According to the Baltimore Classification System, a double-stranded RNA (dsRNA) virus belongs to Group III.
-Classification of Viruses
106
According to the Baltimore Classification System, what group does a positive-sense, single-stranded RNA ((+)ssRNA) virus that requires a DNA intermediate belong to?
According to the Baltimore Classification System, a positive-sense, single-stranded RNA ((+)ssRNA) virus that requires a DNA intermediate belongs to Group VI.
-Classification of Viruses
107
According to the Baltimore Classification System, what group does a positive-sense, double-stranded DNA ((+)ssDNA) virus belong to?
According to the Baltimore Classification System, a positive-sense, single-stranded DNA ((+)ssDNA) virus belongs to Group II.
-Classification of Viruses
108
According to the Baltimore Classification System, what group does a negative-sense, single-stranded RNA ((-)ssRNA) virus belong to?
According to the Baltimore Classification System, a negative-sense, single-stranded RNA ((-)ssRNA) virus belongs to Group V.
-Classification of Viruses
109
According to the Baltimore Classification System, what group does a positive-sense, single-stranded RNA ((+)ssRNA) virus belong to?
According to the Baltimore Classification System, a positive-sense, single-stranded RNA ((+)ssRNA) virus belongs to Group IV.
-Classification of Viruses
110
According to the ICTV Classification System, what taxonomic category ends in -virus?
According to the ICTV Classification System, the taxonomic category that ends in -virus is the genus.
-Classification of Viruses
111
According to the ICTV Classification System, what taxonomic category ends in -virinae?
According to the ICTV Classification System, the taxonomic category that ends in -virinae is the subfamily.
-Classification of Viruses
112
According to the ICTV Classification System, what taxonomic category ends in -virales?
According to the ICTV Classification System, the taxonomic category that ends in -virales is the order.
-Classification of Viruses
113
According to the ICTV Classification System, what taxonomic category ends in -viridae?
According to the ICTV Classification System, the taxonomic category that ends in -viridae is the family.
-Classification of Viruses
114
What occurs when a sample containing virions is streaked on a plate with bacterial growth medium? Why?
No viral growth will be observed after streaking a plate containing bacterial growth medium with virions. This is because viruses do not have the genetic capability to multiply by division; outside of the host cell, they are inert (dormant) particles.
-Cultivation of Viruses
115
What are the possible ways to cultivate viruses?
Virus particles can be cultivated via cell or tissue culture, inoculation in an embryonated egg, and in laboratory animals.
-Cultivation of Viruses
116
What is a cell culture?
Cell culture refers to the removal of cells from an animal or plant and their subsequent growth in a favorable artificial environment. Cell culture involves the growth of dispersed cells in-vitro, either as cells in suspension or as a monolayer on a solid surface such as the inner surface of a polystyrene culture flask.
-Cultivation of Viruses
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What is a primary cell culture?
A primary cell culture is the maintenance of growth of cells dissociated directly from the parental tissue (such as the kidney or liver) of human or animal origin.
-Cultivation of Viruses
118
What are the steps to generate a primary cell monolayer culture?
To generate a primary cell monolayer culture:
1) Take a tissue sample directly from the human or animal patient.
2) Treat the tissue with proteolytic enzymes, such as trypsin, to dissociate the cells.
3) Place the dissociated cells in a culture.
4) Incubate the culture until the monolayer has formed.
- Cultivation of Viruses
119
True or False:
Primary cell cultures are one of the easiest methods to isolate and propagate viruses, but are not commonly used because they are prone to contamination, are difficult to obtain, and have a relatively short lifespan.
False. Despite the fact that primary cell cultures are difficult to obtain, have a relatively short lifespan, and are very susceptible to contamination they are still the best culture system for isolating and propagating viruses.
-Cultivation of Viruses
120
What viral cultivation method is used to generate viral vaccines?
Primary cell cultures are used in producing viral vaccines.
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121
Define subculture.
Subculture, or passage, refers to the transfer of cells from one culture vessel to another culture vessel.
-Cultivation of Viruses
122
What is a secondary (transfer) culture?
A secondary, or transfer, culture is produced when a primary culture is subcultured.
-Cultivation of Viruses
123
What are the two categories of cell lines?
On the basis of the lifespan of the culture, cell lines are categorized into two types:
1) Finite (diploid) cell lines
2) Continuous (immortal, heteroploid) cell lines
- Cultivation of Viruses
124
Which cell line is more homogeneous, a finite (diploid) cell line or a continuous (immortal, heteroploid) cell line?
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A continuous (immortal, heteroploid) cell line is the most homogeneous cell line.
-Cultivation of Viruses
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125
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True or False:
A continuous (immortal, heteroploid) cell line can be obtained by induced transformation of a primary or diploid cell strain to divide infinitely.
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True. A continuous (immortal, heteroploid) cell line can be derived directly from cancer cells or can be produced by inducing the transformation of a primary or diploid cell strain to divide infinitely.
-Cultivation of Viruses
126
What are the three categories are used to describe the shape and appearance of cells in a culture?
Cells in a culture can be divided into three basic categories based on their shape and appearance:
1) Fibroblastic (fibroblast-like)
2) Epithelial-like
3) Lymphoblastic-like
- Cultivation of Viruses
127
If cells in a culture are described as bipolar or multipolar, elongated, and grow attached to a substrate, what morphological category do they belong to?
Fibroblastic (fibroblast-like) cells are bipolar or multipolar, elongated, and grow attached to a substrate.
-Cultivation of Viruses
128
If cells in a culture are described as polygonal, have more regular dimensions, and grow attached to a substrate in discrete patches, what morphological category do they belong to?
Epithelial-like cells are polygonal, have more regular dimensions, and grow attached to a substrate in discrete patches.
-Cultivation of Viruses
129
If cells in a culture are described as spherical and are grown in suspension without attaching to a surface, what morphological category do they belong to?
Lymphoblastic-like cells are spherical and usually grow in suspension without attaching to a surface.
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130
What is a culture medium?
Culture medium is the substance used in a culture that provides all the necessary nutrients (such as amino acids, inorganic salts, vitamins, and glucose) required for the growth of cells.
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131
What is the purpose of adding serum to the culture media?
Serum in culture media is a vital source of adhesion factors, attachment and spreading factors, low molecular weight nutrients, hormones, growth factors, carrier proteins, and regulates the cell membrane permeability.
-Cultivation of Viruses
132
What is the most widely used animal serum supplement for growth medium?
5%-10% fetal bovine serum (FBS) is the most widely used animal serum supplement for growth medium.
-Cultivation of Viruses
133
What is the most widely used animal serum supplement for maintenance medium?
0%-2% fetal bovine serum (FBS) is the most widely used animal serum supplement for maintenance medium.
-Cultivation of Viruses
134
What is the purpose of using a pH indicator in culture media?
pH indicators, such as phenol red, aid in identifying contamination of the culture.
-Cultivation of Viruses
135
True or False:
It is important to not expose viral cultures to carbon dioxide, as it will upset the pH balance of the medium. To avoid overexposure to carbon dioxide, it is common for most cell cultures to be placed in an incubator with 4%-10% oxygen.
False. The growth medium controls the pH of the culture and buffers the cells in culture against changes in the pH. This is usually achieved by including an organic or carbon dioxide-bicarbonate based buffer. Changes in the atmospheric carbon dioxide can alter the pH of the medium; therefore it is necessary to use exogenous carbon dioxide when using medium buffered with a carbon dioxide-bicarbonate based buffer, commonly by incubating the culture in 4%-10% carbon dioxide.
-Cultivation of Viruses
