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Mercy CLS 2: Microbiology > Virology > Flashcards

Virology Flashcards

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Biology 101 flashcards
1
Q

size of viruses

A

20-300 nanometers

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2
Q

ways to classify viruses

A
  • Nature of nucleic acid (RNA or DNA)
  • Morphology/symmetry of protein shell (capsid)
  • Presence or absence of a lipid membrane (envelope)
  • Dimensions of the virion (viral infection particle) and capsid
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3
Q

viral shapes

A

Helical symmetry
Icosahedral symmetry
Spherical
Complex (bacteriophage)

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4
Q

protein coat surrounding the nucleic acid

A

Capsid or nucleocapsid

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5
Q

used to bind to cell surface

A

glycoprotein spikes

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6
Q

viral membrane the carries the viral glycoproteins

made from host cell

A

envelope

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7
Q

RNA viruses must either…

A

encode a nucleic acid polymerase to produce mRNA from RNA templates

Or

use a reverse transcriptase to convert RNA to DNA (retrovirus) and then produce mRNA

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8
Q

——– DNA can be directly translated into mRNA
——– DNA cannot be translated directly; must be copied

A

positive
negative

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9
Q

virus infectious cycle

A

Attachment and entry
Decoding genome information
Genome replication
Assembly and release of viral particles with genome

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10
Q

specimens for viral culture must contain…

A

cells

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11
Q

steps of creating a cell culture medium

A
  • Disassociate tissue into a single cell suspension by mechanical disruption then treatment with proteolytic enzymes
  • Suspend in culture medium and place in plastic flask or plate
  • Cells divide in about 24 to 48 hours and cover plastic surface to form a monolayer
  • Most cells retain viability after being frozen at low temperatures
  • Can pass or split cells (passage) by dispersing them and reestablishing them into a new flask or plate
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12
Q

primary cell culture lifespan

A

5-20 divisions

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13
Q

primary cell culture sources

A

Chicken or mouse embryos, monkey kidneys or humas tissue such as embryonic amnion, kidney, foreskin of respiratory epithelium

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14
Q

diploid cell culture lifespan

A

50 or 100 divisions

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15
Q

diploid cell culture sources

A

Human embryo cells such as WI-38 strain, and MRC-5 derived from human embryonic lung fibroblast cells

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16
Q

Can be propagated or passaged indefinitely in culture

A

continuous cell culture

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17
Q

Usually derived from tumor tissue or by treating a primary cell line with a mutagenic chemical

A

continuous cell culture

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18
Q

Prior to molecular detection, viruses are visualized in infected cells

A

cytopathic effect (CPE)

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19
Q

cytpathic effect examples

A

Rounding up
Detachment
Cell lysis
Formation of fused mulitnucleated cells (Syncytium)

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20
Q

time to development of CPE

A

Some take 1 to 2 days while others may not produce CPE for weeks

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21
Q

respiratory syncytial virus (RSV) CPE

A

giant cells and syncytia formation

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22
Q

advantages of NAAT over viral culture

A
  • Faster
  • More sensitive
  • Detect more viruses than culture
  • Require less skill
  • Can determine viral load for quantitative monitoring
  • Can test as viral syndromic panels
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23
Q

limitations of multiplex viral syndromic panels

A
  • Not all positive results indicate current infection
  • Likelihood of at least one false positive increased in multiplex panels with many targets
  • Even a positive results does not rule out the possibility of another concomitant infection or super infection
  • Does not test for every viral cause of infection
  • Loss of technical expertise of clinical virologist
  • More expensive than using testing for key viral pathogens
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24
Q

3 requirements for viral infection

A
  • Sufficient number of infectious viral particles
  • Access to these particles by submissive and permissive cells
  • Uneducated or dampened antiviral defenses
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25
Q

To be effective, the vaccine must…

A

induce protective immunity in a portion of the population, so it is sufficient to impede person-to-person transmission (herd immunity)

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26
Q

Most antivirals target viral enzymes such as…

A

proteases and nucleic acid synthesizing proteins

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27
Q

can help avoid the appearance of viruses resistant to one treatment or the other

A

the use of two or more drugs with distinct targets

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28
Q

Knowing a virus’s —— helps to reduce testing required to only a few viruses rather than a pan virus approach

A

season

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29
Q

phases of viral infection

A
  • Prodrome – pre-symptomatic shedding
  • Acute phase – shedding decreases and IgM appears
  • Resolution phase – shedding ends and IgG appears
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30
Q

when should viral samples be collected?

A

as soon as possible after onset of symptoms – Likelihood of positive results usually within first 3 days

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31
Q

may need to place sample in ——- for transport

A

viral transport medium (VTM)

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32
Q

VTM example

A

Buffered salt solution such as Hanks with a neutral pH

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33
Q

Most useful VTM should allow simultaneous detection of viruses by…

A

several methods such as culture, antigen detection and NAAT

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34
Q

transport time

A

2-4 hours of collection

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35
Q

preferred transport temp

A

2-8°

Enzymes present in specimens capable of inactivating viruses are less active

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36
Q

Specimens can be held at 2 to 8°C for up to ———- before inoculation onto cell culture

A

1 to 2 days

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37
Q

Freezing of specimens (-70°C or lower) is not recommended for viral isolation (cell culture) unless…

A

specimen processing will not occur within 2 days or more

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38
Q

lose activity with repeated freeze-thaw cycles

A

RSV, CMV and VZV

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39
Q

very susceptible to temperature changes and has about a 90% loss of infectivity after 24 hours at 37°C and 4 days at 4°C

A

RSV

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40
Q

RNA targets (HIV or HCV) sample

A

EDTA-treated whole blood

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41
Q

DNA targets (CMV) require…

A

EDTA-treated blood

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42
Q

Whole blood, used for NAAT, needs to be processed to remove…

A

inhibitors of DNA and RNA polymerases such as heme and the metabolic precursors of heme

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43
Q

Can use ——– for NAAT for diagnosis of HIV, HBV, neonatal HSV and congenital CMV

A

dried blood spots

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44
Q

blood/BM collection for viruses

A

Collect in heparin
Transport at room temperature

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45
Q

CSF collection

A
  • Do not centrifuge – need to maintain cells present in specimen
  • Dilution in VTM can cause false negative results
  • Transport at room temperature and store up to 48 hours at 2 to 8°C or freeze at -70°C if longer storage is required
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46
Q

must extract ——- from CSF
why?

A

Extract nucleic acids prior to testing to remove globulins that inhibit the activity of thermostable polymerases

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47
Q

cells needed for respiratory collection

A

ciliated epithelial cells of the posterior nasopharynx

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48
Q

——- respiratory specimens are not acceptable due to low levels of viruses

A

Anterior nasal and throats
sputum is suboptimal

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49
Q

——- collects more respiratory epithelial cells from posterior nasopharynx

A

Flocked swab

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50
Q

collect HSV from skin lesions without ——— because…

A

bleeding, since neutralizing antibody in blood can impair recovery of virus

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51
Q

Rectal swab is inferior to …

A

2 to 5 mL of liquid stool or 2 to 5 grams of formed stool

52
Q

Can use specially formulated collection paper strips for NAAT for …… (enteric viruses)

A

rotavirus, adenovirus types 40 and 41 and norovirus

53
Q

influenza antigenic differences based on…

A

matrix protein (M) and nucleoprotein (NP)

54
Q

Influenza A are further classified into subtypes by two major surface glycoproteins:

A

Hemagglutinin (HA)
Neuraminidase (NA)

55
Q

occurs due to small changes/mutations in the genes that lead to changes in the surface proteins of the virus

A

antigenic drift

56
Q

major abrupt change in the flu virus resulting in new HA or new HA and NA proteins

A

antigenic shift

57
Q

Occurs only with type A viruses and they are the only flu viruses known to cause pandemics

A

antigenic shift

58
Q

influenza description

A

Enveloped, spherical, with single-strand RNA

59
Q

Late November to December begins with influenza ——-
Transitions to —— in February through April

A

type A
type B

60
Q

influenza tx

A

Amantadine and rimantadine (type A only)

Zanamivir, oseltamivir and peramivir

61
Q

influenza CPE

A

destruction of cell sheet within a week of inoculation

62
Q

Can perform hemadsorption using erythrocytes of different animal species (guinea pig)

A

influenza

63
Q

Types 1 and 2 in October and November, type 3 in late March to April

Severe disease in those with immunocompromised immune systems

A

parainfluenza

64
Q

50% of croup (barking cough) in children

A

parainfluenza (HPIV)

65
Q

HPIV tx

A

Currently no FDA cleared antivirals or vaccines

66
Q

HPIV CPE

A

rounded cells and syncytium formation in 4 to 8 days

67
Q

Gets its name from the characteristic formation of multinucleated giant cells in cell cultures

A

RSV

68
Q

Most serious cause of lower respiratory tract illness in young children and infants

Bronchiolitis, pneumonia

A

RSV

69
Q

Cell culture is the gold standard for —– due to excellent specificity

A

RSV

70
Q

RSV tx

A

Ribavirin and palivizumab (monoclonal antibody)

71
Q

Presents very similar to RSV but poor or no growth in cell cultures

A

human metapneumovirus

72
Q

Derive their name form the predominant site of replication – the nose

A

rhinovirus

73
Q

Causes 2/3 of cases of upper respiratory syndromes known as the common cold

A

rhinovirus

74
Q

rhinovirus CPE

A

Large and small rounded, refractile cells with pyknotic nuclei in 24 hours to 4 days

75
Q

enterovirus description

A

Non-enveloped with single strand RNA

76
Q

Stable in liquid environments and can survive for weeks; Water, body fluids, sewage

A

enteroviruses

77
Q

enterovirus highest incidence

A

young infants and children 5 to 10 years old

78
Q

Most common enteric cause of viral meningitis

A

poliovirus (enterovirus)

79
Q

Hand-foot and mouth disease

A

coxsackievirus (enterovirus)

80
Q

enterovirus CPE

limitation

A

shrinkage and rounding of cells and nuclei exhibit pyknosis

Culture has no real application due to prolonged time for viral isolation

81
Q

enterovirus tx

A

No FDA approved antiviral agents

82
Q

coronavirus description

A

Enveloped RNA virus
Spikes of glycoproteins (peplomers)

83
Q

Shedding of COVID peaks in —– week of disease so patient is often in hospital by then and it is easier to spread virus

A

2nd

84
Q

Coronavirus isolation allowed only in a —– facility

A

BSL 3

85
Q

Culture should not be attempted

Does not grow in most common cell lines
CPE is generally non-specific
Requires a BSL3 facility and procedures
Accidental transmission to laboratory workers has been described

A

coronavirus

86
Q

rotavirus description

A

Nonenveloped, double-stranded RNA

87
Q

norovirus description

A

Nonenveloped, single stranded RNA

88
Q

enteric adenovirus description

A

Nonenveloped, double stranded DNA

89
Q

Prior to vaccination, leading cause of severe dehydrating diarrhea in infants and kid less than 2 years

A

rotavirus

90
Q

Cause large outbreaks: Hospitals, child-care centers, schools, restaurants, nursing homes, cruise ships, military camps

A

norovirus

91
Q

Fever, diarrhea, vomiting, abdominal cramps, lethargy dehydration

A

gastroenteritis viruses

92
Q

gasteroenteritis virus tx

A

No effective antiviral agents

rotavirus now has a vaxx

93
Q

gastroenteritis specimen

A

stool or rectal swab

94
Q

major challenge to gastroenteritis NAAT

A

the presence of inhibitors in sample

Could lead to false negative results

95
Q

gastroenteritis cell culture

A

Time consuming and does not contribute to management of gastroenteritis

96
Q

HSV description

A

Double stranded DNA with lipid rich envelope

97
Q

Readily inactivated by lipid solvents (e.g., ethanol), Lysol, bleach, temperatures >56°C, and pH <5 or >11 with 30 minutes of exposure

A

HSV

98
Q

—— associated with gingivostomatitis, and —— associated with genital lesions

A

HSV1
HSV2

99
Q

HSV becomes latent in …

A

sensory ganglia

100
Q

Most common cause of fatal sporadic encephalitis in immunocompromised

A

HSV

101
Q

not acceptable for diagnosis of HSV encephalitis

A

Culture of CSF

102
Q

Most common viral cause of corneal infection

A

HSV

103
Q

HSV cell lines

A

Mink lung cells, human diploid fibroblasts (MRC-5 and WI-38), human epidermoid carcinoma lines such as Hep-2 and A549

104
Q

HSV CPE

A

cell develop cytoplasmic granulation and become large, round (balloon)and refractile

Clusters of infected cells then lyse and detach

105
Q

HSV tx

A

Acyclovir, valacyclovir penciclovir, and famciclovir

106
Q

results from reactivation of VZV

A

Herpes zoster (shingles)

107
Q

VZV samples collected

A

skin vesicular fluid
blood for dissemination

108
Q

Infects humans of all ages with no seasonal transmission
Often acquired early in life and up to 100% of individuals can be seropositive

A

CMV

109
Q

Prolonged fever, malaise, atypical lymphocytosis and mild hepatitis

Known as heterophile-negative mononucleosis

A

CMV

110
Q

mimics EBV

heterophile-negative

A

CMV

111
Q

Most common viral infection with transplants

A

CMV

112
Q

Large characteristic cells with basophilic intranuclear inclusions of infected tissue

Nuclear inclusion has appearance of “owl’s eyes”

A

CMV

113
Q

replaced cell cultures for CMV due to increased sensitivity

A

Shell Vial assays

114
Q

Human fibroblasts best support growth
CPE and can develop within 24 hours and progress rapidly
Can resemble CPE of adenovirus and varicella-zoster virus

A

CMV

115
Q

serology used to screen blood and organ donors and recipients for…

A

CMV

116
Q
  • Centrifuge specimen onto MRC-5 fibroblasts cells growing on a round cover slip
  • Virus is embedded into the cell layer to begin the replication process faster
  • Incubate 37°C for 16 to 24 hours then apply immunofluorescent antibody stain
A

shell vial assay for CMV

117
Q

CMV tx

A

Ganciclovir, valganciclovir, foscarnet and cidofovir

118
Q

Isolation from urine, respiratory secretions or other bodily fluids within first 3 weeks of life is traditional means of confirming diagnosis of congenital infection in newborns

urine preferred

A

CMV

119
Q

HPV description

A

Nonenveloped, double-stranded DNA

120
Q

HPV —- has the highest risk for cancer

A

16

121
Q

hand and foot warts are common in children and adolescents

Walking barefoot in pool or showers

A

HPV

122
Q

Anogenital warts
Cauliflower-like growths

A

Majority caused by HPV types 6 and 11

123
Q

Oral and upper respiratory tract warts
Potential damage to vocal cords and possibility of respiratory obstruction

A

HPV

124
Q

Three vaccines that target certain types

A

HPV

125
Q

samples for HPV

A

Tissue samples, cervical samples which include exfoliative cells as used for a Pap test, first-void urine, swabs or brushes to ensure dislodged cells, oral rinse or gargle using mouthwash or saline

126
Q

HPV culture

A

cannot be cultured

127
Q

Use for girls who are ≥ 15 years old and those who are HIV positive

A

HPV vaccine

Mercy CLS 2: Microbiology (16 decks)

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