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Mycology and Virology > INTRODUCTION TO VIROLOGY > Flashcards

INTRODUCTION TO VIROLOGY Flashcards

1
Q

containing genetic material (DNA or RNA) surrounded by a protective protein coat and depend on their host for all aspects of their reproduction.

A

Obligate intracellular parasites

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2
Q

Spreads from cell to cell via infectious unit

A

Virion

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3
Q

initiated upon entry, dissociation in a host cell and directs synthesis of viral components by cellular system

A

Host replication

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4
Q

de novo self-assembly from the newly synthesized components

A

Formation of progeny virus particles

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5
Q

 Viruses are not solely pathogenic nuisances; they can be .

A

beneficial

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6
Q

 Not all pathogenic viruses fulfill the

A

Koch’s postulates.

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7
Q

 Viruses can cross

A

species boundaries.

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8
Q

 All viruses must produce (?) that can be translated by cellular ribosomes.

A

mRNA

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9
Q

 Strandedness, is either

A

single single stranded (ss) or double stranded (ds)

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10
Q

 Groups include

A

ssRNA, dsRNA, ssDNA, and dsDNA.

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11
Q

 Polarity include (?), immediate translations for protein synthesis; (?), no immediate translations for the protein.

A

positive sense (+)
negative sense (-)

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12
Q

 Shape of nucleic acid is either

A

linear or circular

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13
Q

for both (+) and (-) senses.

A

Ambisense

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14
Q

Protein shell(coat) that protects the NA genome.

A

Capsid

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15
Q

Basic unit of a capsid.

A

Capsomere

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16
Q

Individual protein subunits that assembles into types of capsids (eg., icosahedral, helical, complex)

A

Capsomere

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17
Q

Required for entry of the infectious virion particle

A

Spike glycoprotein (S)

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18
Q

Most abundant protein (Eg., SARS-CoV-2)

A

Membrane protein (M)

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19
Q

Smallest among the major Structural protein

A

Envelope glycoprotein (E)

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20
Q

single-stranded positive sense RNA genome

A

Nucleocapsid (N)

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21
Q

is based on comparing and contrasting set of characters that can be used to define the properties of any particular taxon.

A

Taxonomic classification

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22
Q

• Four (4) Characteristics used in the Taxonomic Classification:

A
  1. Nature of the nucleic acid (NA) in the virus particles (DNA or RNA)1
  2. Symmetry of the protein (capsid)
  3. Presence or absence of a lipid membrane (envelope)
  4. Dimensions of the virion and capsid
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23
Q

Presence of Nucleic acid
RNA

A

Arenaviridae Flaviviridae
Astroviridae Orthomyxoviridae
Bunyaviridae Paramyxoviridae
Caliciviridae Picornaviridae
Coronaviridae Rhabdoviridae Filoviridae Reo-, Togaviridae

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24
Q

Presence of Nucleic acid
DNA

A

Adenoviridae Parvoviridae
Hepadnaviridae Polyomaviridae
Herpresviridae Poxviridae
Papilomaviridae

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25
Q
  • ALL RNA viruses are “ss” except
A

Reoviridae

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26
Q
  • ALL DNA viruses are “ds” except
A

Parvoviridae

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27
Q
  • ALL RNA viruses have helical capsid symmetry except
A

Calici-, Flavi-, Picorna-, Reo-, and Togaviridae

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28
Q
  • (?), either helical or icosahedral symmetry
A

Retroviridae

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29
Q
  • ALL DNA viruses have icosahedral symmetry except (?) that has a complex symmetry
A

Poxviridae

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30
Q

Withstand harsh environment conditions

A

Naked

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31
Q

Cannot be dried out

A

Enveloped

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32
Q

Resistant to drying, aicids, & detergents

A

Naked

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33
Q

Not stable to acid

A

Enveloped

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34
Q

Many are transmitted fecal-oral route

A

Naked

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35
Q

General must remain in body fluids

A

Enveloped

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36
Q

Types of Capsid

A

Naked
Enveloped

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37
Q

Francis Crick, conceptualized the central dogma for flow of information form DNA genome in all living cells:

A

o DNA → mRNA → protein

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38
Q

The translational machinery for protein synthesis depends on the .

A

host’s cell

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39
Q

But viral genomes comprise both (?) in a variety of conformations.

A

DNA and RNA

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40
Q

allows relationships among viruses with RNA or DNA genomes to be determined on the pathway required for mRNA production.

A

The Baltimore System

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41
Q

The Baltimore System was inspired by

A

David Baltimore, 1971

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42
Q

Assigns viruses to seven (I to VII) distinct classes on the bases of the (!) of their genomes.

A

nature and polarity

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43
Q

Since all viruses must produce (!) that can be translated by cellular ribosomes, knowledge of the composition of the viral genome provides insight into the pathways required to produce mRNA, indicated by arrows

A

mRNA

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44
Q

INITATION

A

Attachment Penetration Uncoating

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45
Q

BIOSYNTHESIS

A

Genome Replication Assemble and Release

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46
Q

 Interaction of a virion with specific receptor site on the surface of a host cell.

A

Attachment

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47
Q

 Receptor binding reflects fortuitous configurational homilies and play an important role in cell tropism and viral pathogenesis.

A

Attachment

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48
Q

 Initiates irreversible structural changes in the virion.

A

Attachment

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49
Q

Penetration
 Accomplish in various ways:

A
  1. Receptor-mediated endocytosis 2. Clathrin- mediated endocytosis 3. Direct penetration 4. Fusion
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50
Q

Interaction of viral protein to host cell is facilitated with a second cellular receptor (coreceptor)

A

Penetration

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51
Q

 Occurs concomitantly with or shortly after penetration.

A

Uncoating

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52
Q

 This is the separation of viral nucleic acid from the virion and genome may be released as free nucleic acid or nucleocapsid.

A

Uncoating

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53
Q

GOAL: specific mRNA must be transcribe for the viral nucleic acid for successful expression and duplication of genetic information

A

Genome Replication

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54
Q

Once accomplished, translation of mRNA begins

A

Genome Replication

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55
Q

 NOTE: different viruses use different pathways to synthesize mRNA depending on the structure of NA (eg., Rhabdoviridae carry RNA Pol to synthesize mRNAs.

A

Genome Replication

56
Q

 RULE: [(-)] sense viruses must supply their own RNA Pol.

A

Genome Replication

57
Q

 Newly synthesize viral genomes and capsid polypeptides assemble together to form progeny viruses.

A

Assemble and Release

58
Q

Assemble and Release
 Effects to the host cell:

A
  1. Cell death 2. Mutation due to chronic persistent infection 3. Viral-induced apoptosis 4. Cytopathic effects
59
Q

Viral Growth Curve

A

Inoculation Eclipse Maturation

60
Q

 Host cell is inoculated with the virus that consequently undergoes attachment.

A

Inoculation

61
Q

 Sometimes the amount of the virus decreases because the visions attached to host cells are not yet considered viruses.

A

Inoculation ñ

62
Q

 Viruses are not being manufactured within host cells. Viral contents enter the cell during the penetration step of the viral life cycle.

A

Eclipse

63
Q

 After genetic material is uncoated, genetic material is copied and viral components are formed during biosynthesis.

A

Eclipse

64
Q

 After synthesis of capsids, enzymes and other materials, new virus particles are formed during the assemble stage.

A

Maturation

65
Q

 Total virus count increases before extracellular virus count increases: there is a lag while visions are being created, but not enough have been created for release to occur.

A

Maturation

66
Q

 Non-enveloped viruses accumulate in cells until cell lysis.

A

Maturation

67
Q

 Enveloped viruses assemble near cell membranes and “bud” off via exocytosis

A

Maturation

68
Q

The process by which viruses cause disease— a collateral outcome of the parasitic nature of viruses.

A

Viral Pathogenesis

69
Q

Individual differences among prospective hosts, group dynamics and behaviors, geography, and climate all influence how efficiently a virus can establish infection within a population.

A

Viral Pathogenesis

70
Q

(?) in the appearances of some viruses may be due to variations in viral particle stability at various temperatures or humidity, changes in the integrity of host barriers (eg., skin or mucosa), or seasonal changes in the life cycles of viral vectors, such as mosquitoes.

A

 Seasonal differences

71
Q

 does not necessarily signify susceptibility to disease.

A

Susceptibility to infection

72
Q

helped to identify the causal relationships between a microbe and the disease it causes in the host; but, these postulates may not be fulfilled when associating some viruses with a particular disease

A

 Koch’s postulates

73
Q

Steps in Viral Pathogenesis

A

Entry and Primary
Viral spread and tropism
Cell injury and Manifestation

74
Q

 Attachment of the virus to the host cell with the subsequent replication of the virus a the site of entry.

A

Entry and primary replication

75
Q

 Viruses spread to other body parts of the body within the host.

A

Viral spread and tropism

76
Q

 The spread of other viruses is tissue specific which is affected by gene enhancers and activating enzymes.

A

Viral spread and tropism

77
Q

 Destruction of virus-infected cell and physiologic alteration seen in host cell

A

Cell injury and Manifestation

78
Q

Types of infection:

A
  1. Acute viral infection
  2. Chronic infection
  3. Latent infection
79
Q

 characterized by rapid onset of disease and relatively brief period of symptoms, eventually resolved within days

A
  1. Acute viral infection
80
Q

 viruses are continually detected even at low levels

A
  1. Chronic infection
81
Q

 viruses in an occult or in a cryptic form most of the time

A
  1. Latent infection
82
Q

• Sites of latency include
for VZV and HSV

A

neurons in the dorsal rectal ganglia (shingles)

83
Q

for CMV

A

T-cells, macrophages

84
Q

for EBV

A

B-cells

85
Q

for HBV

A

Hepatocytes

86
Q

for HPV

A

Epithelium

87
Q

Non-persistent pattern, rapid onset soon after contraction.

A

Patterns of viral diseases

88
Q

Persistent pattern, acute plus complications

A

Patterns of viral diseases

89
Q

Abortive, acute manifestations plus death of the virus due to

A
  1. Non-permissive cells 2. Environmental 3. Defective
90
Q

include morphologic changes on host cells.

A

Cytopathic effects

91
Q

Effects of viruses on cells

A
  1. Morphological alterations
  2. Inclusion bodies
92
Q

• Nuclear shrinking (pyknosis) for

A

Picornaviruses

93
Q

• Proliferation of nuclear membrane for

A

alpha viruses and herpesviruses

94
Q

• Vacuoles in cytoplasm for

A

Polyomaviruses, papillomaviruses

95
Q

• Syncytium formation (cell fusion) for

A

Paramyxoviruses and coronaviruses

96
Q

• Margination and breaking of chromosomes for

A

Herpesviruses

97
Q

• Virion in nucleus for

A

Adenoviruses

98
Q

• Virion in cytoplasm (Negri bodies) for

A

Rabies virus aviruses

99
Q

• Factories in cytoplasm (Guarnieri bodies) for

A

Poxviruses

100
Q

• Clumps of ribosomes for

A

Aren

101
Q

Morphological alterations

A
102
Q

Inclusion bodies

A
103
Q
  1. Have (?) ready
A

all PPEs and materials

104
Q
  1. Check VTM for clarity and turbidity (VTM should be (?) in color. Tap the tube and mix contents)
A

clear and salmon pink

105
Q
  1. Check integrity of the swab and tongue depressor (use only (?)). DO NOT use calcium alginate or swabs with wooden sticks.
A

sterile Dacron or rayon swabs with plastic shafts

106
Q
  1. Check (?) of kits. DO NOT use beyond expiry
A

expiration date

107
Q
  1. DO NOT use (?) which may have been opened
A

swabs or tongue depressors

108
Q
  1. Correctly (?) the patient and (?) the tube prior to collection
A

identify
label

109
Q
  1. Take out the VTM (?)
A

(2-30oC)

110
Q
  1. Label the VTM with the (?). Information should be legible and label should remain attached under all conditions of storage and transport.
A

patient’s full name, date and time of collection

111
Q
  1. Specimens should be collected (?) from onset of infection since it is the time when the virus is in high concentration. DO NOT collect beyond seven (7) days.
A

within seven (7) days

112
Q
  1. Only (?) should perform the procedure
A

qualified and trained staff

113
Q
  1. Remove possible (?) (eg., loose hair)
A

visual obstruction

114
Q
  1. Use a (?) for each individual patient
A

single kit

115
Q
  1. Strictly follow (?) prior to each procedure (eg., biosafety protocols)
A

infection control guidelines

116
Q

Viral Culture Technique

A

Plaque Assay
Embryonated eggs
Viral cell culture

117
Q

Easy to grow. Reliable determination of the titers of viruses

A

Plaque Assay

118
Q

Plaque Assay
1. Virus, bacteria and agar are (?). Monolayers of cultured cells are (?) with a preparation of virus to allow adsorption to cells.
2. After removal of the inoculum, the cells are covered with nutrient medium containing a supplement (most commonly (?)— which forms a gel)
3. When the original infected cells release (?), the gel restricts the spread of viruses to neighboring infected cells.
4. After replication, the virus lyses the bacteria, forming (?) (circular zone of infected cells)

A

mixed, incubated
agar
new progeny particles
plaques

119
Q

• Each plaque is assumed to come from a

A

single viral particle

120
Q

• Reported in plaque forming units

A

(PFU/mL)

121
Q

[A] Single plaque formed by (?) virus in Giorgia bovine kidney cells stained with chromogenic substrate.
[B] Plaques formed by (?) on human HeLa cells stained with crystal violet.
[C] Illustration of the (?) from an initial infected cells to neighboring cell, resulting in a plaque

A

pseudorabies
poliovirus
viral spread

122
Q

• Convenient and inexpensive

A

Embryonated eggs

123
Q

Embryonated eggs

• Hole drilled in Chicken egg shell ((?)after fertilization) and virus is injected into the site appropriate for its replication.

A

5 to 14 days

124
Q

• This method of virus propagation is now routine only for influenza virus.

A

Embryonated eggs

125
Q

• Credited to John Enders, Thomas Weller, and Frederick Robbins (1949) who made the discovery that poliovirus could multiply in cultured cells.

A

Viral cell culture

126
Q

• To prepare a cell culture, tissues are dissociated into a single-cell suspension by mechanical disruption followed by treatment with proteolytic enzymes.

A

Viral cell culture

127
Q

• Cells are suspended in culture medium and place in plastic flasks or covered plates.

A

Viral cell culture

128
Q

• As the cells divide, they cover the plastic surface. Epithelial and fibroblastic cells attached to the plastic and form a monolayer, whereas blood cells such as lymphocytes settle, but do not adhere.

A

Viral cell culture

129
Q

• The cells are grown in a chemically defined and buffered medium optimal for their growth

A

Viral cell culture

130
Q

Viral cell culture

• Commonly used cell lines double in number in (?) in such media

A

24 to 48h

131
Q

Kinds of cell culture

A
  1. Primary cell cultures
  2. Secondary cell cultures
  3. Continuous cell lines
132
Q

, prepared from animal tissues with limited life span usually no more than 5 to 20 cell divisions

A
  1. Primary cell cultures
133
Q

, most common from embryos.

A
  1. Secondary cell cultures
134
Q

, consists of a single cell type that can be propagated indefinitely in culture

A
  1. Continuous cell lines
135
Q

Commonly used primary cultures are derived from monkey kidneys, human embryonic amnion and kidneys, human foreskin and respiratory epithelium, and chicken or mouse embryos

A
  1. Primary cell cultures
136
Q

— primarily used for vaccine production.

A

chicken or mouse embryos

137
Q

Immortal lines that usually derived from tumor strain with a mutagenic chemical or tumor virus (eg., HeLa [Henrietta Lacks] and L and 3T3 cells)

A

Continuous cell lines

Mycology and Virology (20 decks)

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