Virology Introduction PPT Flashcards
(106 cards)
1
Q
is an obligate intracellular parasite, that is among the smallest of all infectious agents and capable of infecting an animal, insect, plant, or bacterial cell.
A
Virus
2
Q
True or False
Virus is incapable of replication without a living host
A
True
3
Q
Virus Replicate only in
A
Living cells
4
Q
Only contain one nucleic acid (DNA or RNA)
A
Virus
5
Q
True or False
Viruses are inert in extracellular
environment
A
True
6
Q
The emergence of a new viral disease across a very large geographic region (worldwide) with prolonged human-to-human transmission
A
Pandemic
7
Q
Most of the pandemics recorded had been caused by an____ virus.
A
influenza
8
Q
Major change in the nucleic acid of a virus.
A
Genetic shift
9
Q
major changes that result in novel viral antigens
A
Antigenic shift
10
Q
minor changes that occur continuously over time as the virus replicates
A
Antigenic drift
11
Q
The protein shell, or coat, that encloses the nucleic acid genome.
A
Capsid
12
Q
Morphologic units seen in the electron microscope on the surface of icosahedral virus particles.
A
Capsomeres
13
Q
represent clusters of polypeptides, but the morphologic units do not necessarily correspond to the chemically defined structural units.
A
Capsomeres
14
Q
A virus particle that is functionally deficient in some aspect of replication.
A
Defective virus
15
Q
The basic protein building blocks of the coat. They are usually a collection of more than one nonidentical protein subunit. The structural unit is often referred to as —
A
protomer
16
Q
A single folded viral polypeptide
A
Subunit
17
Q
The complete virus particle
A
Virion
18
Q
Viruses may be derived from DNA or RNA nucleic acid components of host cells that became able to replicate autonomously and evolve independently. They resemble genes that have acquired the capacity to exist independently of the cell. Some viral sequences are related to portions of cellular genes encoding protein functional domains. It seems likely that at least some viruses evolved in this fashion.
A
Theory of Viral Origin
19
Q
Viruses may be degenerate forms of intracellular parasites. There is no evidence that viruses evolved from bacteria, although other obligately intracellular organisms (eg, rickettsiae and chlamydiae) presumably did so. However, poxviruses are so large and complex that they might represent evolutionary products of some cellular ancestor.
A
Theories of Viral Origin
20
Q
Basis of Classification of virus
A
- Virion morphology
- Virus genome properties
- Genome organization and replication
- Virus protein properties
- Antigenic properties
- Physicochemical properties of the virion
- Biologic properties
21
Q
Virion Morphology
A
- Classification of size
- Determination of the shape
- Type of symmetry
- Presence or absence of peplomers and membranes.
22
Q
Virion Morphology
A
- Classification of size
- Determination of the shape
- Type of symmetry
- Presence or absence of peplomers and membranes.
23
Q
Virion Morphology
A
- Classification of size
- Determination of the shape
- Type of symmetry
- Presence or absence of peplomers and membranes.
24
Q
Spikes that protrude from the envelopes of certain viruses.
A
Peplomers
25
Virus genome properties
- Classification of Nucleic acid (DNA or RNA)
- Size of genome in kilobases pairs or kilo- base pairs (kbp)
- Identification of its strandedness (single or double)
- Identification of sense ( positive or negative)
26
Genome organization and replication
- Gene order
- Number of position of open reading frame
- Strategy replication (pattern of transcription and translation)
- Cellular sites (accumulations of protein, virion assembly, virion release)
27
Virus protein properties
- Number and size of functional activities of structural and non structural protein
- Amino acid sequence
- Modifications (glycosylation, phosphorylation, myristoylation)
- Special function activities (transcriptase, reverse transcriptase, neuraminidase, fusion activities)
28
Physicochemical properties of the virion
- Physical and Chemical properties of the virion
- molecular mass
- ph stability
- susceptibility to physical and chemical agents
(especially ether and detergents)
- Thermal stability
29
Biologic properties
- Natural host range
- Mode of transmission
- Vector of relationships
- Pathogenicity
- Tissue tropisms
- Pathology
30
Icosahedral viruses tend to be—, losing—- after several hours at 37°C
stable
little infectivity
31
Enveloped viruses are much more__, rapidly—- in titer at 37°C
heat labile
dropping
32
Viral infectivity is generally destroyed by— at——,although there are some notable exceptions (eg, hepatitis B virus, polyomaviruses).
Heating at 50-60°C for 30 minutes
33
Many viruses can be stabilized by salts in concentrations of
1 mol/L
34
usually viruses are stable between pH values of
5.0 and 9.0
35
True or False
Some viruses are resistant to acidic conditions.
True
36
All viruses are destroyed by— conditions.
alkaline
37
● Ultraviolet, x-ray, and high-energy particles inactivate viruses.
● The dose varies for different viruses.
Radiation
38
Can be used to distinguish viruses that possess an envelope from those that do not
Ether Susceptibility
39
solubilize lipid constituents of viral membranes
Nonionic detergents
40
also solubilize viral envelopes
Anionic detergents
41
Destroys viral infectivity by reacting with nucleic acid
Formaldehyde
42
Viruses are penetrable to a varying degree by vital dyes such as
toluidine blue,
neutral red,
proflavine.
43
These dyes bind to the viral nucleic acid, and the virus then becomes susceptible to inactivation by visible light.
Photodynamic Inactivation
44
Antibacterial antibiotics and sulfonamides have
no effect on viruses.
45
Larger concentrations of— are required to destroy viruses than to kill bacteria, especially in the presence of extraneous proteins.
chlorine
46
Alcohols, such as isopropanol and ethanol, are relatively—- against certain viruses, especially picornaviruses.
ineffective
47
Common Methods of Inactivating Viruses for Various Purposes
Sterilization
Surface disinfectant
Skin disinfectants
Vaccine production
48
- steam under pressure
- dry heat
- ethylene oxide
- y-irradiation
Sterilization
49
- sodium hypochlorite
- glutaraldehyde
- formaldehyde
- peracetic acid
Surface Disinfectant
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- chlorhexidine
- 70% ethanol
- iodophors
Skin disinfectant
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- formaldehyde
- b-propiolactone
- psoralen + ultraviolet irradiation
- detergents
Vaccine production
52
Viral replication
1. Attachment
2. Penetration
3. Uncoating
4. Macromolecular synthesis
5. Viral assemble
6. Release
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First step of the infectious cycle
ATTACHMENT (Adsorption)
54
- Process by which viruses enter the host cell
- One mechanism of— is fusion of the viral envelope with the host cell membrane
Penetration (virus entry or engulfment)
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- Occurs once the virus are being internalized
- Physical separation of the viral nucleic acid from the outer structural components of virion
Uncoating
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- Production of nucleic acid and protein polymers
Macromolecular synthesis
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- Process by which structural proteins, genomes and in some cases viral enzymes are assembled into virus particles.
- Acquisition of an enveloped is the final step in
viral assemble .
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Release
- Two ways :
- Cell Lysis
- Virus particle budding from cytoplasmic membrane
59
Standard precautions and ——conditions are needed for community and most nonretroviral laboratories.
Biosafety Level 2 (BSL-2)
60
Regulatory requirements include:
- standard microbiologic practices
- training in biosafety protective
- clothing and gloves
- limited access
- decontamination of all infectious
waste.
-BSL-3 and BSL-4
61
True or False
In general, nasopharyngeal aspirates are superior to throat or nasopharyngeal swabs for recovering viruses; however, swabs are considerably more convenient.This is because most respiratory viruses replicate in the ciliated epithelial cells of the posterior nasopharynx.
True
62
Throat, Nasopharyngeal Swab, or Aspirate
Swabs should be—
polyester, Dacron, or rayon with plastic or aluminum shafts.
63
Throat, Nasopharyngeal Swab, or Aspirate
Swabs should be—
polyester, Dacron, or rayon with plastic or aluminum shafts.
64
Throat, Nasopharyngeal Swab, or Aspirate
Swabs should be—
polyester, Dacron, or rayon with plastic or aluminum shafts.
65
Washings and lavage fluid collected during bronchoscopy are excellent specimens for detecting viruses that infect the lower respiratory tract, especially influenza viruses and adenoviruses.
Bronchial and Bronchoalveolar Washes
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Stool and rectal swabs of fecal specimens are used to detect
rotavirus,
enteric adenoviruses (serotypes 40 and 41), and
EVs.
67
- Viral recovery may be increased by processing multiple (two to three) specimens in parallel.
- Improved recovery results with a minimum specimen volume of 10 mL.
Urine
68
True or False
The Urine pH and contaminating bacteria may interfere with viral replication.
True
69
Antisepsis should therefore be performed after the aspiration of the sample, If the sample is collected using a swab, the vesicle should be unroofed (remove the crust) with a sterile needle or scalpel.
Skin and Mucous Membrane Lesions
70
The swab should be —-the base and margin of the lesion to collect virally infected epithelial cells and placed in viral transport media.
rolled over
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The swab should be —-the base and margin of the lesion to collect virally infected epithelial cells and placed in viral transport media.
rolled over
72
True or False
Caution in Skin and Mucous Membrane Lesions should be taken to not cause bleeding, as antibodies present in the blood may neutralize the virus interfering with cultivation.
True
73
True or False
- CSF samples collected by amniocentesis
- Amniotic fluid is collected by lumbar puncture
False
74
used for the detection of viral antibodies as well as NAAT.
Dried Blood Spots
75
Samples can be collected from a capillary finger stick and air dried for 2 hours. Once dried, the sample is placed in a hermetically sealed bag or container containing a desiccant to avoid exposure to moisture and prevent the growth of any contaminating bacteria.
Dried Blood Spots
76
Samples may be transported at room temperature, refrigerated, or frozen at −20°C or lower.
Dried Blood Spots
77
Bone marrow for virus detection should be added to a sterile tube with.
anticoagulant
78
Heparin or EDTA anticoagulants are acceptable for culture. EDTA or ACD (anticoagulant citrate dextrose solution) should be used if the specimen is intended for nucleic acid testing.
Bone marrow
79
Specimens are collected during surgical procedures.
Samples should be transported to the laboratory on wet ice or frozen.
Tissue
80
should be minced and digested with proteolytic enzymes prior to nucleic acid extraction.
Tissue
81
should be minced and digested with proteolytic enzymes prior to nucleic acid extraction.
Tissue
82
Genital specimens often are required for detection of
HSV and HPV.
83
should be collected and processed as previously described for skin lesions and placed in appropriate viral transport media.
Genital lesions or ulcerations
84
collected using a swab or brush and placed in viral transport media.
Cervical specimen
85
Most manufactured endocervical or liquid-based cytology devices are appropriate for nucleic acid testing
True
86
Following the manufacturer’s recommended protocols is essential when processing such as genital specimens
True
87
Salivary gland fluid may also be used for the detection of viral antibodies including secretory IgA, IgM, and IgG. Samples are collected using a sputum collection device, swab, or spatula and placed in transport media.
Oral
88
Acute and convalescent serum specimens may be needed to detect antibody to specific viruses.
Serum for Antibody testing
89
specimens should be collected as soon as possible after the appearance of symptoms.
Acute specimen
90
is collected a minimum of 2 to 3 weeks after the acute specimen.
Convalescent specimen
91
Serum for Antibody Testing an appropriate specimen is —mL of serum collected by venipuncture.
3 to 5
92
Serum can be stored for hours or days at ——or lower before testing.
4°C or for weeks or months at −20°C
93
Serum can be stored for hours or days at ——or lower before testing.
4°C or for weeks or months at −20°C
94
All specimens collected for detection of virus should be processed immediately
True
95
Specimens for viral isolation should not be allowed to sit at room or higher temperature.
True
96
Specimens should be kept cool (4°C) and immediately transported to the laboratory.
True
97
If a delay in transport is unavoidable, the specimen should be refrigerated, not frozen, until processed. Every attempt should be made to process the specimen within 12 to 24 hours of collection.
True
98
If a delay in transport is unavoidable, the specimen should be refrigerated, not frozen, until processed. Every attempt should be made to process the specimen within 12 to 24 hours of collection.
a. the source of the specimen;
b. the clinical history or viruses
suspected; and
c. the date and time of specimen
collection.
99
Viral specimens should be processed in a —-dependent on suspected
viral agents.
BSL-2 or BSL-3
100
When patient cell cultures are manipulated, such as during inoculation or feeding (exchange of cell culture medium), only one patient sample or series of cell culture tubes should be
open at one time.
101
Viral Detection Methods
1. Cytology and Histology
2. Immunodiagnostics (Antigen Detection)
3. Enzyme-Linked Virus-Inducible System
4. Nucleic Acid Based Methods
5. Cell Culture
6. Matrix-Assisted Desorption lonization
Time-of-Fligh Mass Spectrometry
102
Viral Detection Methods
1. Cytology and Histology
2. Immunodiagnostics (Antigen Detection)
3. Enzyme-Linked Virus-Inducible System
4. Nucleic Acid Based Methods
5. Cell Culture
6. Matrix-Assisted Desorption lonization
Time-of-Fligh Mass Spectrometry
103
used primarily to determine a patient's immune status and to confirm the patient's diagnosis when the virus cannot be cultivated in cell culture or detected readily by immunoassay or molecular methods.
Serologic testing
104
In most viral infections,—— after the acute infection resolves, but detectable levels of IgG remain for the life of the patient.
IgM is undetectable 1 to 4 months
105
Viruses can be stored by ——or in liquid nitrogen.
freezing at -70°C
106
Viruses can be stored by ——or in liquid nitrogen.
freezing at -70°C
