12-ADENO Flashcards
(232 cards)
1
Q
Adenovirus was first isolated from which tissue
A
Adenoid tissue
2
Q
To which family and genus do human adenoviruses belong
A
Family Adenoviridae and genus Mastadenovirus
3
Q
Which mucous membranes and tracts does adenovirus infect
A
Respiratory tract; gastrointestinal tract; urogenital tract
4
Q
Name three diseases caused by adenovirus
A
Acute respiratory diseases; conjunctivitis; gastroenteritis
5
Q
What is the most common cause of viral conjunctivitis
A
Adenovirus
6
Q
What unique structural feature do adenoviruses have projecting from each of the 12 vertices
A
A fiber
7
Q
What is the function of the adenovirus fiber
A
Responsible for cell attachment and contains specific antigens important in serotyping
8
Q
Describe the shape and size of the adenovirus virion
A
Icosahedral; 70-90 nm in diameter
9
Q
What is the composition percentage of DNA and protein in adenovirus
A
DNA 13%; protein 87%
10
Q
What type of genome does adenovirus have
A
Double-stranded linear DNA; 26-45 kbp
11
Q
Where does adenovirus replicate in the host cell
A
Nucleus
12
Q
Are adenoviruses enveloped or non-enveloped
A
Non-enveloped (naked)
13
Q
What are the major antigenic proteins of adenovirus
A
Hexon; penton base; fibers
14
Q
How many capsomeres does adenovirus have
A
252 capsomeres
15
Q
How many penton bases and hexon capsomeres are present in adenovirus
A
12 penton bases; 240 hexon capsomeres
16
Q
How many distinct human adenovirus serotypes exist
A
57 serotypes
17
Q
Into how many groups are human adenovirus serotypes divided
A
Seven groups (A to G)
18
Q
Which serotypes belong to adenovirus group A
A
12; 18; 31
19
Q
Which serotypes belong to adenovirus group B
A
3; 7; 11; 14; 16; 21; 34; 35; 50; 55
20
Q
Which serotypes belong to adenovirus group C
A
1; 2; 5; 6; 7
21
Q
Which serotypes belong to adenovirus group D
A
8-10; 13; 15; 17; 19; 20; 22-30; 32; 33; 36-39; 42-49; 51; 53; 54; 56
22
Q
Which serotype belongs to adenovirus group E
A
4
23
Q
Which serotypes belong to adenovirus group F
A
40; 41
24
Q
Which serotype belongs to adenovirus group G
A
52
25
What is the significance of adenovirus fibers in viral classification
They contain specific antigens important for serotyping
26
What type of symmetry do adenoviruses exhibit
Cubic symmetry (icosahedral)
27
Why is it important to know if a virus is enveloped or non-enveloped
Enveloped viruses are susceptible to organic solvents which affects virus handling and disinfection
28
What are enveloped viruses susceptible to
Organic solvents like alcohols and ethers
29
What clinical manifestations are associated with adenovirus infections
Respiratory infections; conjunctivitis; gastroenteritis; hemorrhagic cystitis
30
How is adenovirus transmitted
Respiratory secretions; contact with contaminated objects; waterborne routes
31
What preventive measures help reduce adenovirus transmission
Good hand hygiene and disinfection with heat or bleach
32
Which adenovirus types are associated with pharyngoconjunctival fever
Types 3 and 7
33
Which adenovirus types are known for causing severe respiratory disease outbreaks
Types 7; 14; 55
34
What rare syndromes can adenovirus cause
Viral meningitis; encephalitis; hepatitis; cardiac disorders
35
What is the first step in adenovirus replication
Attachment of the virus to host cells via fiber structures
36
Which receptor does the adenovirus fiber protein primarily bind to
Coxsackie-adenovirus receptor (CAR)
37
What is the secondary receptor involved in adenovirus internalization
Penton base interacting with integrin
38
How does adenovirus enter the host cell after attachment
Clathrin-mediated endocytosis (CME) via integrin interaction
39
What happens to the adenovirus after internalization into endosomes
The endosome acidifies causing capsid disassembly and release of the virion into the cytoplasm
40
What cellular structure helps transport adenovirus particles to the nucleus
Microtubules
41
Where does adenovirus uncoating begin and end
Begins in the cytoplasm and completes in the nucleus
42
What is released during adenovirus uncoating
Viral double-stranded DNA
43
How long does the adenovirus replication cycle take in cultured cells
Approximately 30 hours
44
What is the role of the fiber protein in adenovirus attachment
Binds to the primary receptor CAR on host cells
45
What is the role of the penton base protein in adenovirus entry
Interacts with integrin to promote internalization via endocytosis
46
What type of endocytosis is used by adenovirus for cell entry
Clathrin-mediated endocytosis
47
What triggers the release of adenovirus from the endosome
Acidification of the endosome causing capsid changes and membrane disruption by protein VI
48
How does adenovirus DNA enter the nucleus
After capsid disassembly at the nuclear pore
49
What viral proteins are involved in adenovirus DNA replication
Terminal protein (TP)
50
What is the function of the terminal protein in adenovirus replication
Acts as a primer covalently attached to the 5' end of the viral DNA
51
How does adenovirus DNA replication differ from mammalian DNA replication
Uses a strand displacement mechanism instead of Okazaki fragments
52
What are the two phases of the adenovirus life cycle separated by DNA replication
Early phase and late phase
53
What is the main focus of the early phase of adenovirus replication
Expression of regulatory proteins to modify host cell and activate viral genes
54
What is the main focus of the late phase of adenovirus replication
Production of structural proteins for virion assembly
55
How is adenovirus released from the host cell
Virally induced cell lysis
56
What cellular receptor do group B adenoviruses use for attachment
CD46
57
What is the role of protein VI in adenovirus entry
Disrupts the endosomal membrane to facilitate viral escape into the cytoplasm
58
What happens to the viral DNA after it enters the nucleus
Associates with histones and uses host transcription machinery for gene expression
59
What cellular process is stimulated by adenovirus binding to integrin
Actin polymerization facilitating endocytosis
60
What is the approximate number of new virus particles produced per infected cell
50
61
What is the half-life of adenovirus particles moving from endosomes to cytosol
Approximately 5 minutes
62
What is the significance of clathrin-coated vesicles in adenovirus infection
They mediate virus internalization into the host cell
63
What is the role of microtubules in adenovirus infection
Transport virus particles from cytoplasm to nucleus
64
What is the nature of the adenovirus genome
Linear double-stranded DNA with terminal protein covalently attached
65
What is the mechanism of adenovirus DNA replication initiation
Protein-primed DNA synthesis starting with covalent addition of dCMP to precursor terminal protein
66
What cellular transcription factors enhance adenovirus DNA replication initiation
NFI and Oct-1
67
What happens to the precursor terminal protein (pTP) during replication
Cleaved by viral protease to mature terminal protein (TP) for packaging into virions
68
What are the capsomeres that are components of the adenovirus capsid
Hexons and pentons
69
What is the role of hexons and pentons in adenovirus structure
They form the major structural proteins of the viral capsid that holds the double-stranded DNA
70
Which transcription units produce early proteins involved in adenovirus replication
E1 to E4 proteins
71
What is the function of E1A and E1B proteins in early adenovirus infection
Induce host cell to enter S phase and suppress apoptosis to allow viral replication
72
What does the E3 region encode
Proteins that counteract host antiviral defense mechanisms such as downregulating MHC 1 expression
73
What is the significance of the E4 region proteins
Regulate protein stability and can replace the entire E4 region for viral replication
74
Which early transcription unit encodes viral DNA polymerase
terminal protein
75
What is the function of the terminal protein in adenovirus DNA replication
Acts as a primer covalently linked to the 5’ end of viral DNA to initiate replication
76
How does adenovirus replicate its DNA
Using a single-stranded DNA displacement mechanism starting at inverted terminal repeats
77
What controls the expression of late adenovirus genes
The major late promoter (MLP)
78
What do the late transcriptional units (L1–L5) encode
Viral structural proteins including hexons and pentons
79
Why is RNA splicing important in adenovirus gene expression
It removes introns and generates multiple mature mRNAs for viral protein synthesis
80
Where does viral DNA replication take place
In the nucleus of the host cell
81
What is the goal of early gene expression in adenovirus infection
To produce enzymes and proteins needed for viral DNA replication
82
What is the goal of late gene expression in adenovirus infection
To produce structural proteins for assembling new virions
83
What happens to the viral DNA after uncoating
It enters the nucleus as a nucleoprotein complex for transcription and replication
84
What is the role of the E1B-55K and E1B-19K proteins
To block apoptosis and prevent premature death of infected cells
85
How do adenovirus early proteins affect the host cell cycle
They bind cellular proteins like retinoblastoma to push the cell from G1 to S phase
86
What is the function of the E3-gp19K protein
Downregulates MHC 1 to evade cytotoxic T cell recognition
87
What is the role of the E4-ORF6 protein
Forms a complex with E1B-55K to regulate protein stability during infection
88
What is the significance of the major late promoter (MLP)
It drives expression of late genes coding for structural proteins after DNA replication
89
What is the nature of the adenovirus genome
Linear double-stranded DNA with inverted terminal repeats and covalently attached terminal protein
90
What is the mechanism of adenovirus DNA replication initiation
Protein-primed DNA synthesis starting with covalent addition of dCMP to precursor terminal protein
91
What cellular factors enhance adenovirus DNA replication initiation
Transcription factors NFI and Oct-1 that bind the origin and bend DNA
92
What is the function of the DNA-binding protein (DBP) in replication
Protects single-stranded DNA and stimulates DNA polymerase activity
93
What is the outcome of adenovirus DNA replication
Production of multiple copies of viral DNA for packaging into new virions
94
Where does adenovirus virion morphogenesis occur
In the nucleus
95
What happens to viral polypeptides after synthesis
They are rapidly transported to the cell nucleus
96
What is the first step in adenovirus capsid formation
Capsomeres self-assemble into empty-shell capsids
97
Which capsomeres form the adenovirus capsid
Hexon
98
What is the role of the packaging signal in adenovirus assembly
It is a cis-acting DNA element necessary for DNA capsid recognition
99
Which protein acts as the ATP-driven motor for viral DNA encapsidation
IVa2 protein
100
What proteins bind the packaging sequence to facilitate viral DNA incorporation
IVa2 and L4-22K proteins
101
What is the function of adenovirus protease during maturation
Proteolytic cleavage of six capsid and precursor core proteins to mature the virion
102
What are the characteristics of mature adenovirus virions
Stable
103
What percentage of hexon capsomeres and viral DNA are incorporated into virions
About 20% of hexon capsomeres and 10% of viral DNA
104
How many virus particles are produced per infected cell
Approximately 100
105
What is the duration of the adenovirus infectious cycle
About 24 hours
106
What do viral associated (VA) RNAs do
Protect the virus from the antiviral effect of interferon by preventing activation of an interferon-inducible kinase
107
What is the role of E3 region proteins in host defense evasion
Inhibit cytolysis of infected cells and block tumor necrosis factor α–induced cytolysis
108
How does the E3 gp19-kDa protein protect infected cells
Blocks movement of MHC class I antigens to the cell surface preventing cytotoxic T lymphocyte–mediated lysis
109
What cytopathic effects does adenovirus cause in human cell cultures
Marked rounding
110
What type of intranuclear inclusions are seen in adenovirus-infected cells
Rounded basophilic inclusions exhibiting crystalline arrangements
111
Do adenovirus infections induce syncytia or multinucleated giant cells
No
112
Which adenovirus species establish latent infections in tonsils and adenoids
Species C adenoviruses
113
Which adenovirus types are most commonly detected in latent infections
Types 1,2,5,6,7
114
What is the host range of human adenoviruses
Narrow; infection of cells from other species usually results in abortive replication
115
What cellular changes are observed in adenovirus cytopathology in human tissues
Rounding of tubular epithelial cells with basophilic stipplings (inclusion bodies)
116
What is gene therapy
Medical approach to treat or prevent disease through gene correction
117
Which virus is commonly used as a vector in gene therapy
Adenovirus
118
Name three applications of adenovirus vectors
Cancer therapy; gene therapy; genetic immunization
119
What is a major limitation of adenovirus vectors
High immunogenicity and preexisting immunity to subgroup C adenoviruses
120
What protein drives viral DNA encapsidation in adenovirus assembly
IVa2 protein
121
What are the main capsomeres forming the adenovirus capsid
Hexon; penton base; fiber
122
Where does adenovirus virion morphogenesis occur
In the nucleus
123
What is the function of adenovirus protease
Proteolytic cleavage of capsid and core proteins for virion maturation
124
What percentage of hexon capsomeres are incorporated into virions
About 20%
125
What is the role of the packaging signal in adenovirus assembly
DNA element necessary for capsid recognition and DNA packaging
126
Which animal is susceptible to adenovirus type 5 infection
Newborn hamsters
127
Which adenovirus serotypes induce tumors in newborn hamsters
12; 18; 31
128
Are adenoviruses implicated in human cancer causation
No
129
What is the role of viral associated (VA) RNAs
Protect virus from interferon-induced antiviral effects
130
What adenovirus protein blocks MHC class I antigen presentation
E3 gp19-kDa protein
131
What cytopathic effect is characteristic of adenovirus infection in cell culture
Cell rounding; enlargement; grape-like cell clusters
132
What is the main function of E1B proteins
Suppress apoptosis in infected cells
133
What is the major late promoter (MLP) responsible for
Expression of late genes coding for structural proteins
134
What is the typical duration of adenovirus infectious cycle
About 24 hours
135
What vaccine uses adenovirus as a viral vector
Janssen/Johnson & Johnson COVID-19 vaccine
136
What is the advantage of adenovirus vectors in gene delivery
High transduction efficiency and short-term gene expression
137
What is the mechanism of adenovirus DNA replication initiation
Protein-primed single-stranded DNA displacement
138
What is the function of the terminal protein in adenovirus DNA replication
Primer covalently linked to 5’ end of viral DNA
139
What is the role of E3 region proteins in immune evasion
Inhibit cytolysis and tumor necrosis factor α–induced apoptosis
140
What is the role of the L4-22K protein
Binds packaging sequence with IVa2 to facilitate DNA encapsidation
141
What is the function of adenovirus fiber protein
Mediates attachment to host cell receptor CAR
142
What is the secondary receptor involved in adenovirus entry
Integrin interacting with penton base
143
What is clathrin-mediated endocytosis
Vesicular transport mechanism for adenovirus internalization
144
What is the host range of human adenoviruses
Narrow; abortive replication in non-human cells
145
What is the role of microtubules in adenovirus infection
Transport virus particles to the nucleus
146
What is the function of E3 gp19-kDa protein
Blocks MHC class I transport to cell surface preventing T cell lysis
147
What is the role of adenovirus protease in maturation
Cleaves precursor proteins to produce stable infectious virions
148
What is the typical yield of adenovirus particles per infected cell
Approximately 100
149
Which cells are primarily infected and support adenovirus replication
Epithelial cells of the respiratory and urinary tracts
150
Where do adenoviruses persist as latent infections
Adenoids and tonsils
151
Do adenoviruses spread beyond regional lymph nodes
No
152
Which adenovirus groups persist latently and shed in feces
Group C viruses
153
What type of infection do most adenoviruses cause in the intestinal epithelium
Subclinical infections
154
Which adenovirus serotypes cause gastrointestinal disease
Types 40 and 41
155
Can a single adenovirus serotype cause different clinical diseases
Yes
156
Which adenovirus serotypes are associated with gastroenteritis
18; 41; 52
157
Which adenovirus types are most commonly associated with human illness worldwide
Types 1 to 7
158
How is adenovirus commonly transmitted
Oral contact; droplet spread; indirect contact with contaminated objects
159
What are typical respiratory symptoms of adenovirus infection
Cough; nasal congestion; fever; sore throat
160
Which adenovirus types commonly infect infants and children
Group C viruses especially types 1; 2; 5
161
Which adenovirus types commonly infect adolescents and adults
Types 3; 4; 7
162
Which adenovirus types cause 10-20% of childhood pneumonia
Types 3; 7; 21
163
What is the mortality rate of adenoviral pneumonia in very young children
Up to 10%
164
Which adenovirus serotype caused a severe respiratory disease outbreak in 2007
Type 14
165
Which adenovirus types cause acute respiratory disease syndrome in military recruits
Types 4; 7; occasionally type 3
166
What are symptoms of acute respiratory disease syndrome caused by adenovirus
Fever; sore throat; nasal congestion; cough; malaise
167
What is pharyngoconjunctival fever
An adenovirus-associated outbreak illness with fever and conjunctivitis
168
Which adenovirus types cause pharyngoconjunctival fever
Types 3 and 7
169
What is epidemic keratoconjunctivitis
A serious
170
Which adenovirus types cause epidemic keratoconjunctivitis
Types 8; 19; 37
171
What are clinical features of epidemic keratoconjunctivitis
Acute conjunctivitis; keratitis; possible subepithelial corneal opacities lasting up to 2 years
172
How long can adenovirus remain viable on surfaces like sinks and towels
Several weeks
173
What is the importance of hand hygiene in adenovirus infections
Prevents transmission from contaminated surfaces
174
What cytopathic effect does adenovirus infection induce in corneal cells
Inflammation through viral capsid interaction with host cells
175
Which adenovirus types are particularly pathogenic in children and can cause fatal disease
Types 3 and 7
176
What is the host range of human adenoviruses
Narrow; humans only
177
Can adenovirus infections be asymptomatic
Yes
178
What is the typical incubation period for adenovirus infections
About 8 days
179
What are common portals of entry for adenovirus infection
Mucous membranes of respiratory
180
What are risk factors for adenovirus infection
Crowded environments such as schools
181
What types of adenovirus infections are more severe in immunocompromised individuals
Respiratory tract infections; colitis; hepatitis; hemorrhagic cystitis; meningoencephalitis
182
Which adenovirus types cause hemorrhagic cystitis
Types 11 and 21
183
What neurological conditions can adenoviruses cause
Meningitis and encephalitis (mainly types 3 and 7)
184
What is the significance of adenovirus shedding after infection
Prolonged shedding can occur for months
185
Which adenovirus serotypes are etiologically associated with infantile gastroenteritis
Serotypes 40 and 41
186
What type of infection do most adenovirus serotypes cause in the intestinal epithelium
Subclinical infections
187
Why are adenovirus serotypes 40 and 41 considered fastidious
They grow poorly in culture systems and are difficult to cultivate
188
What symptoms are commonly caused by adenovirus serotypes 40 and 41
Fever; diarrhea; vomiting; abdominal pain
189
What is the typical duration of illness caused by adenovirus 40 and 41
Approximately 10 days
190
How are enteric adenoviruses transmitted
Fecal-oral route
191
Which population is most affected by adenovirus 40 and 41 gastroenteritis
Young children
192
What is the incubation period for adenovirus 40 and 41 infections
3 to 10 days
193
Are adenovirus 40 and 41 infections usually severe
No
194
Can adenovirus 40 and 41 cause respiratory symptoms
Yes
195
What percentage of children with diarrhea have enteric adenoviruses detected
About 9%
196
What is the rank of adenovirus 40 and 41 among causes of infantile gastroenteritis
Third most common after rotavirus and norovirus
197
Can asymptomatic shedding of adenovirus 40 and 41 occur
Yes
198
What diagnostic methods are used for detecting adenovirus 40 and 41
PCR assays; direct examination of fecal extracts; cell culture (difficult)
199
What is the host range of adenovirus serotypes 40 and 41
Humans only
200
What is the infectious dose of adenovirus 40 and 41
Unknown
201
What is the significance of low Ct values in PCR for adenovirus 40 and 41
Indicates active infection rather than asymptomatic shedding
202
Are adenovirus 40 and 41 infections seasonal
They occur year-round with peaks in warmer months
203
What settings are common for adenovirus 40 and 41 transmission
Day-care centers; households; hospitals
204
What is the main preventive measure against adenovirus 40 and 41 transmission
Hand hygiene and sanitation
205
What is the clinical relevance of detecting non-40/41 adenovirus types in stool
Often represent asymptomatic shedding
206
What type of antibodies rise in humans after adenovirus infection
Complement-fixing antibodies to group antigens
207
Which serologic test detects infection by any adenovirus group member but has low sensitivity
Complement fixation test
208
Which serologic tests can identify specific adenovirus serotypes
Antibody neutralization and hemagglutination inhibition tests
209
What indicates a positive hemagglutination test
Clumping (agglutination) of red blood cells
210
What indicates a positive hemagglutination inhibition test
No agglutination due to antibodies blocking binding sites
211
What are advantages of serological tests for adenovirus diagnosis
Fast performance; accessibility; faster turnaround time
212
What are disadvantages of serological tests
Lower specificity and sensitivity compared to molecular methods
213
What is the confirmatory test for adenovirus infection
Molecular methods such as PCR
214
Which adenovirus serotypes are most common in respiratory infections in infants
Types 1; 2; 5; 6
215
Which adenovirus serotypes commonly affect school-aged children
Types 3 and 7
216
Which adenovirus serotypes cause gastroenteritis
Types 40 and 41
217
What are common modes of transmission of adenovirus
Direct contact; fecal-oral route; respiratory droplets; contaminated fomites
218
Which adenovirus types are common among military recruits
Types 3; 4; 7
219
Which adenovirus types cause swimming pool conjunctivitis
Types 3 and 7
220
Which adenovirus types cause epidemic keratoconjunctivitis
Types 19 and 37
221
What is the preferred specimen type for adenovirus detection in respiratory infections
Nasopharyngeal or oropharyngeal swabs
222
What laboratory method is preferred for detecting fastidious adenovirus types 40 and 41
Antigen assays in stool samples
223
Which cell lines are commonly used for adenovirus culture
A-549; HEp-2; HeLa cells
224
What molecular test is routinely used for adenovirus diagnosis
Polymerase chain reaction (PCR) assays
225
What does a four-fold rise in antibody titer between acute and convalescent sera indicate
Recent adenovirus infection
226
What is the role of viral neutralization tests
Identify specific adenovirus serotypes by measuring type-specific antibodies
227
What is the significance of detecting adenovirus DNA by PCR
Confirms presence of viral infection and can provide typing information
228
What is the main preventive measure against adenovirus transmission
Careful hand washing and disinfection
229
What vaccine types are used against adenovirus types 4 and 7
Live adenovirus vaccines in gelatin-coated capsules
230
What is the shape and genome type of adenoviruses
Non-enveloped icosahedral viruses with double-stranded DNA genome
231
Which adenovirus group establishes latent infections in tonsils and adenoids
Group C (types 1; 2; 5; 6; 7)
232
What is the clinical significance of adenovirus fibers
Mediate attachment to host cells and contribute to infectivity
