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Parvoviridae Flashcards

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1
Q

Simplest DNA viruses

A

Parvoviruses

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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

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3
Q

Parvovirus B19 has a tropism for which cells?

A

Erythroid Progenitor Cells

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4
Q

Parvovirus B19 causes which common childhood exanthema?

A

Erythema infectiosum (fifth disease)

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5
Q

Parvovirus B19 disease in normal adults?

A

Polyarthralgia-arthritis Syndrome

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6
Q

Parvovirus B19 causes what disorder in patients with haemolytic disorders?

A

Aplastic crisis

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7
Q

Parvovirus B19 in immunocompromised individuals?

A

Chronic Anemia

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8
Q

Parvovirus B19 pre-birth

A

Fetal Death

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9
Q

A newly detected parvovirus found in respiratory and stool specimens of children with ARDS, but role still uinproven.

A

Human Bocavirus

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10
Q

Parvoviruses: Virion properties (shape, diameter and number of capsomeres)

A

Icosahedral
18 - 26 nm in diameter
32 capsomeres

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11
Q

Composition of Parvovirus

A

20% DNA

80% Protein

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12
Q

Proteins of Parvovirus

A

1 major VP2, which is 90% of virion protein

1 minor VP1

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13
Q

Which encodes the virion proteins of parvoviruses?

A

Encoded by an overlapping, in-frame DNA sequence

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14
Q

PV: VP2 is identical in sequence to which portion of VP1?

A

Carboxy Portion of VP1

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15
Q

Parvoviruses: Encapsulated or nonencapsulated?

A

Nonencapsulated, no envelope, nada, nil

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16
Q

Replication of parvoviruses

A

Dependent on functions of dividing cells

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17
Q

True or false. There are both autonomous-replicating and defective parvoviruses.

A

True

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18
Q

Molecular weight of parvoviruses.

A

5.5 - 6.2 x 10^6

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19
Q

Buoyant density of parvoviruses

A

1.39 - 1.42 g/cm^3

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20
Q

Virions of parvoviruses are extremely resistant to inactivation. They are stable at pH of?

A

pH 3 and 9

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21
Q

Virions of parvoviruses can withstand heating at what temperature?

A

Temp of 56C for 60 minutes

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22
Q

Parvoviruses can be inactivated by:

A

Formalin
Beta-propiolactone
Oxidizing agents

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23
Q

Has 5596 nucleotides.

Usually encapsidates primarily DNA strands complementary to viral mRNA.

A

Autonomous virus (B19)

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24
Q

Has 4680 bases

Encapsidates DNA strands of both polarities with equal frequency into separate virions.

A

Defective Virus (AAV-2)

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25
Q

2 subfamilies of Parvovirus

A
  1. Densovirinae

2. Parvovirinae

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26
Q

Subfamily of parvoviruses which infects insects

A

Densovirinae

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27
Q

Subfamily of parvoviruses which infects vertebrates

A

Parvovirinae

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28
Q

Human Parvovirus B19 (Type 1) is the most common member of which genus?

A

Erythrovirus genus

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29
Q

Give the 2 new human genotypes identified recently that differ about 10% in nucleotide sequence from B19.

A

Strains K71- Type 2

Strains V9- Type 3

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30
Q

Human bocavirus is under what genus?

A

Bocavirus genus

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31
Q

Members of Parvovirus genus that cause serious veterinary diseases

A

Feline panleukopenia virus

Canine parvovirus

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32
Q

Parvovirus genus that contains members that are DEFECTIVE and DEPENDENT ON HELPER VIRUS for replication.

A

Genus Dependovirus

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33
Q

Genus Dependovirus depends on which helper viruses?

A

Adenovirus

Herpes virus

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34
Q

True or False. Human “adeno-associated virus” have not been linked with any disease.

A

True

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35
Q

Human B19 parvovirus is difficult to culture. Which cells are permissive for B19 infection?

A

Primary Erythrooid Progenitors

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36
Q

Cellular receptor for Parvovirus B19 is?

A

Blood group P antigen (globoside)

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37
Q

P antigen is expressed on which 7 tissues?

A 
Mature erythrocytes
Erythroid progenitors
Megakaryocytes
Endothelial cells
Placenta
Fetal liver
Fetal heart
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38
Q

Because P antigen is expressed on few tissues only, this explains its ____ tropism.

A

narrow tissue tropism

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39
Q

Parvovirus DNA replication occurs in what part of the cell?

A

Nucleus

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40
Q

Effect of Parvoviruses on resting cells?

A

None. Parvoviruses do not have the ability to stimulate resting cells to initiate DNA synthesis.

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41
Q

What are involved for Parvovirus replication?

A
  • 1 or more DNA polymerases

- 2 capsid proteins

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42
Q

These are used as primers to initiate DNA synthesis

A

Terminal sequences on the linear parvovirus DNA

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43
Q

Parvovirus replication results in?

A

Cell death

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44
Q

This essential nonstructural protein of Parvovirus is required for viral replication and modulating host cell genes.

A

Non-structural viral protein (NS1)

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45
Q

Narrate replication cycle of Parvovirus

A
  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
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46
Q

Give the clinical feature of the PV B19 human infection: Erythema infectiosum in children

A

Cutaneous rash

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47
Q

Give the clinical feature of the PV B19 human infection: Erythema infectiosum in adults

A

Arthralgia-arthritis

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48
Q

Give the clinical feature of the PV B19 human infection: Transient Aplastic Crisis

A

Severe Acute Anemia due to hemolysis

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49
Q

Give the clinical feature of the PV B19 human infection: Pure Red Cell Aplasia in the Immunodeficient

A

Chronic Anemia

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50
Q

Give the clinical feature of the PV B19 human infection: Fetus with Hydrops Fetalis

A

Fatal Anemia

51
Q

The 1st phase of illness with flu-like symptoms in PV B19 Human Infection coincides with?

A

Viremia on days 6 - 12, manifested as myalgia, fever and malaise

52
Q

The 2nd phase of illness with flu-like symptoms in PV B19 Human Infection coincides with?

A

Appearance of rashes and arthralgia-arthritis on day 18

53
Q

What are the 3 major sites of PV B19 viral replication?

A

Adult marrow
Blood cells
Fetal liver

54
Q

PV B19 replication leads to cell death that interrupts?

A

Red cell production

55
Q

Antibodies made following B19 infections.

A

IgM and IgG

56
Q

Persistent parvovirus infections occuring in immunodeficient patients who fail to make virus-neutralizing antibodies result in?

A

Anemia

57
Q

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.

A 
blood
skin
tonsil
liver
synovial tissues
58
Q

Modes of transmission of parvoviruses?

A
  1. Respiratory route
  2. Parenterally by blood transfusion and infected blood products (clotting and Ig concentrates)
  3. Vertically from mother to fetus
59
Q

PVB19 are found in which specimens?

A

Blood and respiratory secretions

60
Q

PVB19 can be isolated from urine and feces. True or False?

A

False

61
Q

Prevalence of antibodies to B19 is higher among _____ than general population

A

Haemophiliacs

62
Q

Why do some clotting factor concentrates end up contaminated?

A

B19 is resistant to harsh treatments that inactivate enveloped viruses.

63
Q

MOT of Human Bocavirus

A

Respiratory route

64
Q

Several pathogenic parvoviruses of animals replicate in intestinal mucosal cells and cause?

A

Enteritis

65
Q

Common manifestation of human parvovirus B19.

A

Erythema infectiosum

66
Q

Erythema infectiosum is most common in which child group?

A

Early school age

Children with acute wheezing

67
Q

Characteristic rash in erythema infectiosum

A

Slapped Cheek Appearance

68
Q

A prominent feature of erythema infectiosum in adults

A

Involvement of the joints in the hands and knees

69
Q

Symptoms of erythema infectiousm mimic?

A

Rheumatoid arthritis

70
Q

Incubation period in erythema infectiosum?

A

IP of 1 - 2 weeks, may extend up to 3 weeks

71
Q

Viremia in erythema infectiosum occurs ____ week after infection and persists for ______

A

Viremia occursd 1 week after infection and persists for 5 days

72
Q

PVB19 in erythema infectiosum is present in which specimens?

A

Nasal washes

Gargle specimens

73
Q

Most probable site of viral shedding in erythema infectiosum

A

Pharynx

74
Q

First phase of erythema infectiosum occurs at ___ (time)

A

End of the 1st week

75
Q

Manifestations in the 1st phase of erythema infectiosum

A 
Flu-like symptoms:
Fever
Malaise
Myalgia
Chills
Itching
76
Q

First episode of erythema infectiosum coincides with?

A
  1. Viremia and reticulocytopenia

2. Detection of circulating IgM-parvovirus immune complexes

77
Q

2nd phase of erythema infectiosum begins after IP of?

A

17 days

78
Q

2nd phase of erythema infectiosum is manifested as?

A
  1. Erythematous facial rash
  2. Lace-like rash on limbs and trunk
  3. Joint symptoms, esp. in adults
79
Q

2nd phase of erythema infectiosum is short-lived, with rash fading after?

A

After 2 - 4 days, although joint symptoms may persist longer

80
Q

Antibody that appears 1 day post infection in erythema infectiosum

A

Specific IgG antibodies

81
Q

Parvovirus B19 transient aplastic crisis may complicate cases of?

A

Chronic Hemolytic Anemia, e.g. Sickle Cell Disease, Thalassemia, Acquired Hemolytic Anemia in adults

82
Q

Transient aplastic crisis in PVB19 infection may also occur after which operation?

A

Post bone marrow transplant

83
Q

Abrupt cessation of RBC synthesis in PVB19 infection is reflected by:

A
  • Absence of erythroid precursors in marrow

- Accompanied by rapid worsening of anemia

84
Q

Temporary arrest in production of RBCs become apparent only in patients with chronic haemolytic anemia because of?

A

short lifespan of their erythrocytes

85
Q

True or False. 7-day interruption in erythropoiesis would not be expected to cause detectable anemia in normal person.

A

True

86
Q

Few anemia patients with PVB19 infection have this sign

A

rash

87
Q

Symptoms of Transient Aplastic Crisis in PVB19 infection occur during which phase?

A

Viremic Phase

88
Q

B19 may establish persistent infections and cause chronic suppression of bone marrow and chronic anemia in immunocompromised patients which is identified as?

A

Pure Red Cell Aplasia (severe anemia)

89
Q

Immunideficeint patients with pure red cell aplasia are dependent on?

A

Blood transfusions

90
Q

PVB19 Pure Red Cell Aplasia has been observed in which populations?

A

Those with congenital immunodeficiency, malignancies, AIDS, and organ transplants

91
Q

Maternal infection with B19 may pose a serious risk to the fetus, resulting in ______ and ____due to severe anemia

A

HYDROPS FETALIS AND FETAL DEATH

92
Q

True or False. Fetal loss occurs in less than 10% of primary maternal infections. Therefore, overall risk during pregnancy is low.

A

True

93
Q

Fetal death in PVB19 Hydrops Fetalis occurs most commonly when?

A

before the 20th week of pregnancy

94
Q

True or False. There is frequent intrauterine transmission of human parvovirus (with vertical transmission rates of 30% or higher)

A

True

95
Q

Maternal-fetal transmission of pVB19 may occur most commonly in pregnant women with

A

High plasma viral loads

96
Q

Most sensitive assay for PVB19 detection of viral DNA

A

PCR

97
Q

During acute infections, viral loads in the blood can reach approximately ___ seen in PCR

A

10^11 genome copies/ml

98
Q

PCR assays based on B19 may miss non-B19 strains due to?

A

Sequence differences

99
Q

The only assay available for human bocavirus

A

PCR

100
Q

Serologic assays of PVB19 are based on

A

recombinant parvovirus B19 antigens produced in vitro using bacterial or baculovirus expression systems to measure antibodies

101
Q

Appears to be optimal as antigen for antibody detection in serologic assays in PVB19

A

VP2 virus-like particles

102
Q

Detection of ____ is indicative of recent infection with B19; it is present for ____ mos. after infection

A

B19 IgM antibody present after 2 - 3 months

103
Q

B19 ___ antibody against conformational epitopes on VP1 and VP2 persists for years, although antibody responses against linear epitopes decline within mos. Of postinfection

A

IgG

104
Q

Since antibodies may not be found in chronic B19 infections in immunodeficient patients, how can PVB19 infection be diagnosed?

A

By detection of viral DNA

105
Q

Can identify high-titered B19 virus in clinical samples

A

Antigen detection assays

106
Q

Has been used to detect B19 antigens in fetal tissues and in bone marrow

A

IHC Antigen detection assays

107
Q

True or False. Viral isolation is used to detect PVB19 infection.

A

False.

108
Q

Antibodies against PVB19 most often develop between ages?

A

5 and 19 years

109
Q

Main path of PVB19 transmission:

A

transfer among siblings and children in schools and daycare centers

110
Q

True or False. Transmission of B19 from patients with aplastic crisis to hospital staff has been documented

A

True

111
Q

True or False. Patients with aplastic crisis are likely to be infectious during the course of their illness.

A

True

112
Q

True or False. Patients with fifth disease are probably no longer infectious by the time of onset of rash.

A

True

113
Q

In PVB19 infection, Fifth disease and transient aplastic crisis are treated

A

Symptomatically

114
Q

These can sometimes ameliorate persistent B19 infections in immunocompromised patients and in those with anemia.

A

Commercial immunoglobulin preparations containing neutralizing antibodies to human parvovirus

115
Q

Treatment for bocavirus infections.

A

None

116
Q

Vaccine for Human PV infection

A

None

117
Q

Antiviral drug therapy for PVB19

A

None

118
Q

Practices helpful in the prevention and control of PVB19

A

hand washing and not sharing drinks

119
Q

should be followed among health care workers from patients with aplastic crisis and from immunodeficient patients with chronic B19 infection

A

STANDARD infection control practices

  • Hand Hygiene
  • PPE
  • Respiratory hygiene and cough etiquette
120
Q

DNA genome of Parvovirus

A

single stranded

121
Q

Best describes replication of human infections by Parvovirus B19

A

Uses blood group antigen P as cellular receptor

122
Q

Available as treatment or preventive for Parvovirus B19 infection

A

Commercial immunoglobulin

123
Q 
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
A

C. Cause anemia

Microbiology (7 decks)

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