Parvoviridae Flashcards
1
Q
Simplest DNA viruses
A
Parvoviruses
2
Q
Because of small coding capacity of their genome, viral replication of Parvovirus is dependent on functions supplied by?
A
Replicating host cells and co-infecting helper cells
3
Q
Parvovirus B19 has a tropism for which cells?
A
Erythroid Progenitor Cells
4
Q
Parvovirus B19 causes which common childhood exanthema?
A
Erythema infectiosum (fifth disease)
5
Q
Parvovirus B19 disease in normal adults?
A
Polyarthralgia-arthritis Syndrome
6
Q
Parvovirus B19 causes what disorder in patients with haemolytic disorders?
A
Aplastic crisis
7
Q
Parvovirus B19 in immunocompromised individuals?
A
Chronic Anemia
8
Q
Parvovirus B19 pre-birth
A
Fetal Death
9
Q
A newly detected parvovirus found in respiratory and stool specimens of children with ARDS, but role still uinproven.
A
Human Bocavirus
10
Q
Parvoviruses: Virion properties (shape, diameter and number of capsomeres)
A
Icosahedral
18 - 26 nm in diameter
32 capsomeres
11
Q
Composition of Parvovirus
A
20% DNA
80% Protein
12
Q
Proteins of Parvovirus
A
1 major VP2, which is 90% of virion protein
1 minor VP1
13
Q
Which encodes the virion proteins of parvoviruses?
A
Encoded by an overlapping, in-frame DNA sequence
14
Q
PV: VP2 is identical in sequence to which portion of VP1?
A
Carboxy Portion of VP1
15
Q
Parvoviruses: Encapsulated or nonencapsulated?
A
Nonencapsulated, no envelope, nada, nil
16
Q
Replication of parvoviruses
A
Dependent on functions of dividing cells
17
Q
True or false. There are both autonomous-replicating and defective parvoviruses.
A
True
18
Q
Molecular weight of parvoviruses.
A
5.5 - 6.2 x 10^6
19
Q
Buoyant density of parvoviruses
A
1.39 - 1.42 g/cm^3
20
Q
Virions of parvoviruses are extremely resistant to inactivation. They are stable at pH of?
A
pH 3 and 9
21
Q
Virions of parvoviruses can withstand heating at what temperature?
A
Temp of 56C for 60 minutes
22
Q
Parvoviruses can be inactivated by:
A
Formalin
Beta-propiolactone
Oxidizing agents
23
Q
Has 5596 nucleotides.
Usually encapsidates primarily DNA strands complementary to viral mRNA.
A
Autonomous virus (B19)
24
Q
Has 4680 bases
Encapsidates DNA strands of both polarities with equal frequency into separate virions.
A
Defective Virus (AAV-2)
25
2 subfamilies of Parvovirus
1. Densovirinae
| 2. Parvovirinae
26
Subfamily of parvoviruses which infects insects
Densovirinae
27
Subfamily of parvoviruses which infects vertebrates
Parvovirinae
28
Human Parvovirus B19 (Type 1) is the most common member of which genus?
Erythrovirus genus
29
Give the 2 new human genotypes identified recently that differ about 10% in nucleotide sequence from B19.
Strains K71- Type 2
| Strains V9- Type 3
30
Human bocavirus is under what genus?
Bocavirus genus
31
Members of Parvovirus genus that cause serious veterinary diseases
Feline panleukopenia virus
| Canine parvovirus
32
Parvovirus genus that contains members that are DEFECTIVE and DEPENDENT ON HELPER VIRUS for replication.
Genus Dependovirus
33
Genus Dependovirus depends on which helper viruses?
Adenovirus
| Herpes virus
34
True or False. Human “adeno-associated virus” have not been linked with any disease.
True
35
Human B19 parvovirus is difficult to culture. Which cells are permissive for B19 infection?
Primary Erythrooid Progenitors
36
Cellular receptor for Parvovirus B19 is?
Blood group P antigen (globoside)
37
P antigen is expressed on which 7 tissues?
```
Mature erythrocytes
Erythroid progenitors
Megakaryocytes
Endothelial cells
Placenta
Fetal liver
Fetal heart
```
38
Because P antigen is expressed on few tissues only, this explains its ____ tropism.
narrow tissue tropism
39
Parvovirus DNA replication occurs in what part of the cell?
Nucleus
40
Effect of Parvoviruses on resting cells?
None. Parvoviruses do not have the ability to stimulate resting cells to initiate DNA synthesis.
41
What are involved for Parvovirus replication?
- 1 or more DNA polymerases
| - 2 capsid proteins
42
These are used as primers to initiate DNA synthesis
Terminal sequences on the linear parvovirus DNA
43
Parvovirus replication results in?
Cell death
44
This essential nonstructural protein of Parvovirus is required for viral replication and modulating host cell genes.
Non-structural viral protein (NS1)
45
Narrate replication cycle of Parvovirus
1. Parvovirus binds to erythrocyte P Ag and enters the cell
2. Translocation of viral DNA to the host nucleus
3. Transcription of non-structural RNA
4. Transcription of capsid protein RNA
5. Protein translation
6. Capsid assembly
7. Non-structural protein action on viral DNA
8. Capsid translocation to nucleus
9. DNA replication
10. Insertion of DNA into intact capsids
11. Virus released
12. Cell lysis
46
Give the clinical feature of the PV B19 human infection: Erythema infectiosum in children
Cutaneous rash
47
Give the clinical feature of the PV B19 human infection: Erythema infectiosum in adults
Arthralgia-arthritis
48
Give the clinical feature of the PV B19 human infection: Transient Aplastic Crisis
Severe Acute Anemia due to hemolysis
49
Give the clinical feature of the PV B19 human infection: Pure Red Cell Aplasia in the Immunodeficient
Chronic Anemia
50
Give the clinical feature of the PV B19 human infection: Fetus with Hydrops Fetalis
Fatal Anemia
51
The 1st phase of illness with flu-like symptoms in PV B19 Human Infection coincides with?
Viremia on days 6 - 12, manifested as myalgia, fever and malaise
52
The 2nd phase of illness with flu-like symptoms in PV B19 Human Infection coincides with?
Appearance of rashes and arthralgia-arthritis on day 18
53
What are the 3 major sites of PV B19 viral replication?
Adult marrow
Blood cells
Fetal liver
54
PV B19 replication leads to cell death that interrupts?
Red cell production
55
Antibodies made following B19 infections.
IgM and IgG
56
Persistent parvovirus infections occuring in immunodeficient patients who fail to make virus-neutralizing antibodies result in?
Anemia
57
Persistence of low levels of B19 DNA, and to a lesser extent virus type 2 DNA, has also been detected in which 5 tissues of immunocompetent volunteers.
```
blood
skin
tonsil
liver
synovial tissues
```
58
Modes of transmission of parvoviruses?
1. Respiratory route
2. Parenterally by blood transfusion and infected blood products (clotting and Ig concentrates)
3. Vertically from mother to fetus
59
PVB19 are found in which specimens?
Blood and respiratory secretions
60
PVB19 can be isolated from urine and feces. True or False?
False
61
Prevalence of antibodies to B19 is higher among _____ than general population
Haemophiliacs
62
Why do some clotting factor concentrates end up contaminated?
B19 is resistant to harsh treatments that inactivate enveloped viruses.
63
MOT of Human Bocavirus
Respiratory route
64
Several pathogenic parvoviruses of animals replicate in intestinal mucosal cells and cause?
Enteritis
65
Common manifestation of human parvovirus B19.
Erythema infectiosum
66
Erythema infectiosum is most common in which child group?
Early school age
| Children with acute wheezing
67
Characteristic rash in erythema infectiosum
Slapped Cheek Appearance
68
A prominent feature of erythema infectiosum in adults
Involvement of the joints in the hands and knees
69
Symptoms of erythema infectiousm mimic?
Rheumatoid arthritis
70
Incubation period in erythema infectiosum?
IP of 1 - 2 weeks, may extend up to 3 weeks
71
Viremia in erythema infectiosum occurs ____ week after infection and persists for ______
Viremia occursd 1 week after infection and persists for 5 days
72
PVB19 in erythema infectiosum is present in which specimens?
Nasal washes
| Gargle specimens
73
Most probable site of viral shedding in erythema infectiosum
Pharynx
74
First phase of erythema infectiosum occurs at ___ (time)
End of the 1st week
75
Manifestations in the 1st phase of erythema infectiosum
```
Flu-like symptoms:
Fever
Malaise
Myalgia
Chills
Itching
```
76
First episode of erythema infectiosum coincides with?
1. Viremia and reticulocytopenia
| 2. Detection of circulating IgM-parvovirus immune complexes
77
2nd phase of erythema infectiosum begins after IP of?
17 days
78
2nd phase of erythema infectiosum is manifested as?
1. Erythematous facial rash
2. Lace-like rash on limbs and trunk
3. Joint symptoms, esp. in adults
79
2nd phase of erythema infectiosum is short-lived, with rash fading after?
After 2 - 4 days, although joint symptoms may persist longer
80
Antibody that appears 1 day post infection in erythema infectiosum
Specific IgG antibodies
81
Parvovirus B19 transient aplastic crisis may complicate cases of?
Chronic Hemolytic Anemia, e.g. Sickle Cell Disease, Thalassemia, Acquired Hemolytic Anemia in adults
82
Transient aplastic crisis in PVB19 infection may also occur after which operation?
Post bone marrow transplant
83
Abrupt cessation of RBC synthesis in PVB19 infection is reflected by:
- Absence of erythroid precursors in marrow
| - Accompanied by rapid worsening of anemia
84
Temporary arrest in production of RBCs become apparent only in patients with chronic haemolytic anemia because of?
short lifespan of their erythrocytes
85
True or False. 7-day interruption in erythropoiesis would not be expected to cause detectable anemia in normal person.
True
86
Few anemia patients with PVB19 infection have this sign
rash
87
Symptoms of Transient Aplastic Crisis in PVB19 infection occur during which phase?
Viremic Phase
88
B19 may establish persistent infections and cause chronic suppression of bone marrow and chronic anemia in immunocompromised patients which is identified as?
Pure Red Cell Aplasia (severe anemia)
89
Immunideficeint patients with pure red cell aplasia are dependent on?
Blood transfusions
90
PVB19 Pure Red Cell Aplasia has been observed in which populations?
Those with congenital immunodeficiency, malignancies, AIDS, and organ transplants
91
Maternal infection with B19 may pose a serious risk to the fetus, resulting in ______ and ____due to severe anemia
HYDROPS FETALIS AND FETAL DEATH
92
True or False. Fetal loss occurs in less than 10% of primary maternal infections. Therefore, overall risk during pregnancy is low.
True
93
Fetal death in PVB19 Hydrops Fetalis occurs most commonly when?
before the 20th week of pregnancy
94
True or False. There is frequent intrauterine transmission of human parvovirus (with vertical transmission rates of 30% or higher)
True
95
Maternal-fetal transmission of pVB19 may occur most commonly in pregnant women with
High plasma viral loads
96
Most sensitive assay for PVB19 detection of viral DNA
PCR
97
During acute infections, viral loads in the blood can reach approximately ___ seen in PCR
10^11 genome copies/ml
98
PCR assays based on B19 may miss non-B19 strains due to?
Sequence differences
99
The only assay available for human bocavirus
PCR
100
Serologic assays of PVB19 are based on
recombinant parvovirus B19 antigens produced in vitro using bacterial or baculovirus expression systems to measure antibodies
101
Appears to be optimal as antigen for antibody detection in serologic assays in PVB19
VP2 virus-like particles
102
Detection of ____ is indicative of recent infection with B19; it is present for ____ mos. after infection
B19 IgM antibody present after 2 - 3 months
103
B19 ___ antibody against conformational epitopes on VP1 and VP2 persists for years, although antibody responses against linear epitopes decline within mos. Of postinfection
IgG
104
Since antibodies may not be found in chronic B19 infections in immunodeficient patients, how can PVB19 infection be diagnosed?
By detection of viral DNA
105
Can identify high-titered B19 virus in clinical samples
Antigen detection assays
106
Has been used to detect B19 antigens in fetal tissues and in bone marrow
IHC Antigen detection assays
107
True or False. Viral isolation is used to detect PVB19 infection.
False.
108
Antibodies against PVB19 most often develop between ages?
5 and 19 years
109
Main path of PVB19 transmission:
transfer among siblings and children in schools and daycare centers
110
True or False. Transmission of B19 from patients with aplastic crisis to hospital staff has been documented
True
111
True or False. Patients with aplastic crisis are likely to be infectious during the course of their illness.
True
112
True or False. Patients with fifth disease are probably no longer infectious by the time of onset of rash.
True
113
In PVB19 infection, Fifth disease and transient aplastic crisis are treated
Symptomatically
114
These can sometimes ameliorate persistent B19 infections in immunocompromised patients and in those with anemia.
Commercial immunoglobulin preparations containing neutralizing antibodies to human parvovirus
115
Treatment for bocavirus infections.
None
116
Vaccine for Human PV infection
None
117
Antiviral drug therapy for PVB19
None
118
Practices helpful in the prevention and control of PVB19
hand washing and not sharing drinks
119
should be followed among health care workers from patients with aplastic crisis and from immunodeficient patients with chronic B19 infection
STANDARD infection control practices
- Hand Hygiene
- PPE
- Respiratory hygiene and cough etiquette
120
DNA genome of Parvovirus
single stranded
121
Best describes replication of human infections by Parvovirus B19
Uses blood group antigen P as cellular receptor
122
Available as treatment or preventive for Parvovirus B19 infection
Commercial immunoglobulin
123
```
Which is not a shared property of human erythroviruses and bocaviruses?
A. Small, nonevnveloped virus particles
B. Difficult to culture
C. Cause anemia
D. Global distribution
E. No vaccine exists
```
C. Cause anemia
