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Liz's Serology/Virology Module 1 > The Clinical Virology Laboratory > Flashcards

The Clinical Virology Laboratory Flashcards

1
Q

Specimen collection:

- Samples may be collected from the site of ____ ____ or from a site where the virus is being ____ (asymptomatically)

A

Viral pathology; shed

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2
Q

When should specimen be collected after onset of symptoms?

A

As soon as possible after onset of symptoms

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3
Q

What is the viral transport medium used for?

A

Used to prevent drying, maintain viability of virus, inhibit growth of contaminants

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4
Q

What specimen are placed in transport medium and what specimens are not?

A

Are: specimen from contaminated body sites

Are not: specimen from sites that are free from usual flora

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5
Q

Controls pH and keeps sample moist; prevents drying

A

Hanks Balanced salt solution or buffered broth

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6
Q

Stabilizes or “cushions” virus; uses fetal bovine serum, albumin, and gelatin

A

Proteinaceous supplement

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7
Q

Inhibits growth of bacteria and fungi

A

Antibiotics

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8
Q

Signals the pH and indicates if pH is “off”; red/orange color change

A

pH indicator

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9
Q

Collect in a sterile screw-capped container; do NOT use transport medium

A

Spinal fluid

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10
Q

Rub on surface to collect cells and place in transport medium

A

Swab collection

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11
Q

Collect in a sterile container; do NOT use transport medium

A

Urine collection

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12
Q

Collect in anticoagulant such as heparin, EDTA, or sodium citrate; do NOT use transport medium

A

Whole blood collection

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13
Q

If a sample will be processed w/in 3-5 days, use ____ to store and ship on ____ ice

A

Refrigerator; wet

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14
Q

If a sample will be processed after 3-5 days, use ____ at ____C or lower. Ship on ____ ice

A

Freezer; -70C; dry

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15
Q

If respiratory syncytial virus (RSV) or cytomegalovirus (CMV) is suspected, what DON’T you do?

A

DO NOT FREEZE!

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16
Q

Two general steps in processing most clinical samples for viral culture

A

Centrifugation and addition of antibiotics

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17
Q

Following centrifugation of transport medium, the ____ is used to inoculate the cell culture tubes

A

Supernatant

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18
Q

Following centrifugation of transport medium, the ____ is used to prepare Ag smears for immunofluorescence testing

A

Sediment

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19
Q

In whole blood samples, the ____ are spearated out and used to inoculate cell cultures

A

Leukocytes

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20
Q

In urine samples, ____-____ urine is used to inoculate cell cultures

A

Well-mixed

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21
Q

Cell cultures freshly explanted from tissue of origin; may have indigenous contaminants (e.g., rhesus monkkey kidney)

A

Primary cell culture

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22
Q

Cell cultures have diploid c’some number; can be passed 50x so it can’t survive long term (e.g., MRC-5, MRHF)

A

Diploid (normal)

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23
Q

Cell cultures that have heteroploid c’some number; originate from cancer tissue; can be passed indefinitely (e.g., A549)

A

Established (heteroploid)

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24
Q

In a cell culture tube, how do tissues grow?

A

Cells grow in a single layer on one side of the tube called a “monolayer” and are on their side to ensure they’re bathed in medium

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25
Q

Inoculation performed by adding processed fluid to the cell culture tube

A

Standard inoculation

26
Q

Inoculation procedure performed where the cell culture medium is decanted from the tube, processed material is applied to the monolayer, incubated in a slant rack (1hr at 35C), excess inoculum is removed and discarded, and fresh cell culture medium is added

A

Adsorption inoculation

27
Q

Incubation temperature of inoculated cell culture tubes

A

36-37C on rotating and stationary racks (to keep the specimen out of the lid)

28
Q

____ ____ media contains the same components as transport media but have added enrichments such as amino acids, vitamins, and other nutrients

A

Cell culture

29
Q

Color of cell culture medium in healthy cell culture tube

A

Peach and clear

30
Q

Cell culture medium color in a tube that is contaminated w/ bacteria or fungi

A

Bright yellow and turbid

31
Q

Cell culture medium color in which the pH is too basic

A

Bright cherry pink

32
Q

How are cell culture tubes examined under a light microscope?

A
  • 10x w/ reduced light
  • Railroad track to keep media in bottom of tube
  • Look for changes in cell morphology
33
Q

Changes in the cell morphology of viruses including swelling, shrinking, and detachment from the vessel

A

Cytopathogenic effect (CPE)

34
Q

When are cell culture tubes routinely examined?

A

On alternate days for 14 days

35
Q

The only cell culture that is examined for only 7 days

A

Herpes Simplex Virus (HSV)

36
Q

When are CMV cultures examined?

A

30 days, slowest grower

37
Q

Viral identity is PREDICTED by what 4 factors?

A
  • Characteristic appearance of CPE
  • TIme to appearance of the CPE
  • Cell line in which teh CPE appears
  • Source of the clinical sample
38
Q

Viral identity is CONFIRMED by what 2 factors?

A
  • Virus-infected cells are reacted w/ Abs of known specificity and when they bind, identity confirmed
  • Most common confirmatory method is immunofluorescence
39
Q

Procedure that can help detect viruses by replacing the cell culture medium w/ a dilute suspension of erythrocytes (from a guinea pig) and refrigerating in a slant rack at 4C for 30 min

A

Hemadsorption (HAD)

40
Q

Describe a positive HAD test

A

RBCs stick to monolayer

41
Q

Describe a negative HAD test

A

RBCs don’t stick to the monolayer and float free in the tube

42
Q

Shell vial system procedure

A
  • Clinical sample placed directly on monolayer
  • Centrifuge at low speed for 1 hour
  • Add medium and incubate
  • Decant and add fixative
  • Add stain to coverslip in vial
  • Coverslips removed and mounted on a slide
  • Fluorescence microscope to examine
43
Q

Shell vials are not evaluated for ____

A

CPE

44
Q

Advantages of shell vial

A
  • Quicker detection
  • Shorter turnaround time
  • no CPE to read
45
Q

Disadvantages to shell vial system

A
  • Tedious to read

- Virus-specific (rather than “open system”)

46
Q

Why are shell vials flexible?

A

Specificity can be changed by changing the type of cells on the monolayer and the monoclonal Abs used

47
Q

Monolayers of cells that include two different types of cells grown together

A

Co-cultivated cell lines

48
Q

What are some marketed names for co-cultivated cell lines?

A
  • R-mix (respiratory viruses)
  • E-mix (enteric viruses)
  • H&V-mix (HSV, CMV, VZV)
49
Q

Advantages of co-cultivated cell lines?

A
  • Cell lines retain usual characteristics of susceptibility to viruses
  • Virology labs do not need to stock as many types of cell cultures
  • Same as shell vial advantages
50
Q

Disadvantages of co-cultivated cell lines?

A

Same as shell vial (tedious to read, virus-specific)

51
Q

Explain the meaning behind the picomaviridae family

A

Small RNA viruses

52
Q
  • Have fecal/oral route of transmission
  • Replicate in bowel but produce pathology at sites outside the bowel
  • Most grow in standard cell cultures
  • Difficult to differentiate from each other and from rhinoviruses
  • Molecular methods are best for detection, ESPECIALLY for CSF samples
A

Enteroviruses

53
Q
  • Replicates in the bowel
  • Moves to CNS to produce pathology
  • Recent change from oral to injection vaccine
  • Extinct in Western Hemisphere
A

Poliovirus

54
Q
  • Transmission and replication in the bowel

- Pathology may be CNS but more often in the heart

A

Coxsackievirus A and B

55
Q
  • Transmission and replication same as polio

- May be isolated when disease is not present; “orphan”

A

Echovirus (aka parechoviruses)

56
Q

What does E.C.H.O stand for?

A

E → Enteric
C → Cytopathogenic
H → Human
O → Orphan

57
Q

Member of Picomaviridae family but is NOT an enterovirus, proliferate in upper respiratory tract and causes common cold, diagnosed clinically

A

Rhinovirus

58
Q

Why is processing of most clinical samples required prior to their inoculation into cell cultures?

A

Must be treated to remove contaminating organisms and other agents taht may be toxic or infective for cell cultures

59
Q

When specimens are collected on swabs and sent to the lab in viral transport medium, what steps are performed on the sample before inoculation of cell culture tubes?

A
  • If swab is received in transport medium, medium is vortexed and then removed
  • Liquid transport medium, which now contains specimen material, is centrifuged (if antibiotics aren’t included in transport medium, add them)
60
Q

Why is more than one type of cell culture tube used in most viral cultures?

A

Virologists select an array of cell cultures that’re susceptible to a variety of human viral pathogens, especially those frequently associated w/ infections of anatomical site from which specimen was collected

61
Q

What does the insignia or label on cell culture tubes tell you?

A

The insignia/label is located on the opposite side of the monolayer

Liz's Serology/Virology Module 1 (5 decks)

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