Viral diagnostics

Question 1

What kind of rash would measles cause?

Answer 1

Maculopapular rash

Question 2

What kind of rash would shingles cause?

Answer 2

Dermatomal distribution

Question 3

Which virus causes shingles?

Answer 3

Herpes Zoster virus

Question 4

List four things which can be measured to detect viruses

Answer 4

The whole virus itself
Protein components of the virus* (IF, EIA)
Genetic components of the virus* (PCR)
The host response* (EIA)

Note: These things can be quantified to work out viral load

Question 5

List two methods of detecting viral antigens?

Answer 5

Immunofluorescence

Enzyme immunoassay

Question 6

How can you detect the viruses’ DNA or RNA?

Answer 6

PCR

Question 7

How are antibodies detected?

Answer 7

Enzyme immunoassay

Question 8

What is sensitivity?

Answer 8

The test’s ability to correctly identify positive samples

Question 9

What is specificity?

Answer 9

The test’s ability to correctly identify negative samples

Question 10

List five viruses where quantification of the genome is important for diagnosis and monitoring

Answer 10

HIV
HBV
HCV
CMV in immunocompromised people
EBV in immunocompromised

Question 11

List typical samples used for PCR/IF of respiratory viruses

Answer 11

Endotracheal secretions (ET)
Bronchoalveolar lavage (BAL)
Throat swab
Nasopharyngeal aspirate (NPA)

Every Thursday Boris Asks Lupton To Say Nice Penis A?

Question 12

List three viruses one may find in a stool sample, and how these would be identified

Answer 12

To detect:
Rotavirus
Adenovirus
Norovirus

Via PCR or EIA

Question 13

List two viruses detected in the urine

Answer 13

BK virus

Adenovirus

Question 14

List two viruses detected in the CSF

Answer 14

Herpes

Enteroviruses

Question 15

When would you use clotted blood as a sample?

Answer 15

For antibody detection using serology

Question 16

When would you use blood with EDTA?

Answer 16

For viral load testing

PCR

Question 17

When would you use saliva samples?

Answer 17

Serology (Ab or Ag)

PCR

Question 18

Which antibody indicates current infection?

Answer 18

IgM

Question 19

Which antibody indicates previous infection/vaccination?

Answer 19

IgG in the absence of IgM

Question 20

What’s the problem with IgM testing?

Answer 20

Low specificity i.e. high false positive results

Question 21

What test can be done to overcome the ambiguity regarding IgM results?

Answer 21

Antibody avidity test

Question 22

What would low and high antibody avidity test results show?

Answer 22

Low in early stages of infection

High means we’re past the infection

Question 23

What markers are used to detect HIV and using what type of test?

Answer 23

p24 antigen
Antibody against HIV

via ELISA

Question 24

What further tests must be done if a patient tests positive for HIV?

Answer 24

Confirmatory assay (to exclude false positives(=)
Typing (HIV1 vs 2)
Repeat bloods
Viral load testing via EDTA blood
Genotyping
Baseline resistance testing

Question 25

Which viruses have point of care testing?

Answer 25

HIV | RSV (respiratory syncytial virus)

Question 26

Why do we not grow cells with viruses?

Answer 26

POOR specificity and sensitivity Slow Fiddly

Question 27

What do we still use cell culture for in terms of viruses?

Answer 27

Phenotypic antiviral susceptibility testing (HSV - herpes simplex virus)

Question 28

What type of microscope can be used to view viruses?

Answer 28

Electron microscope (light microscope can't detect it)

Question 29

Is EM used?

Answer 29

Rarely

Question 30

Describe how immunofluorescence works

Answer 30

You add labelled antibodies to a slide with potential viral particles and shine a light through

Question 31

Discuss the pros and cons of immunofluorescence

Answer 31

Pro: Rapid Inexpensive Cons: Subjective and depends on skill of technician Depends on quality of sample

Question 32

When is IF used nowadays (give an example) and what is the abbreviation for this?

Answer 32

Direct detection of viral antigens in clinical samples such as respiratory viruses DIF

Question 33

Which method would you use to detect respiratory viruses?

Answer 33

PCR

Question 34

List the types of swabs done for respiratory tract infections

Answer 34

Endotracheal secretions Bronchoalveolar lavage Throat swab / nose swab Nasopharyngeal aspirate

Question 35

Give examples of respiratory tract viruses

Answer 35

``` Influenza Parainfluenza RSV Rhinovirus Human metapneumovirus (HMPV) Adenovirus Bocavirus Coronavirus ```

Question 36

State the samples you would take for meningitis and how these would be tested

Answer 36

CSF (PCR) Stool/Throat swabs (PCR) Blood (serology and PCR)

Question 37

List three viruses detected in the CSF that can cause meningitis/encephalitis

Answer 37

Herpes simplex virus (HSV) Varicella zoster virus (VZV) Enterovirus

Question 38

What meningitis/encephalitis causing virus would be detectable via stools and throat swabs?

Answer 38

Enterovirus

Question 39

What meningitis/encephalitis causing virus would be detectable in blood?

Answer 39

West Nile virus Japanese encephalitis virus Arbovirus

Question 40

What is an arbovirus?

Answer 40

Any virus transmitted via mosquitoes, ticks or other arthropods

Question 41

What CNS-disease causing viruses commonly affect immunocompromised people?

Answer 41

CMV EBV John Cunningham (JC virus)

Question 42

What CNS-disease causing viruses would you look for in a young child with febrile fits?

Answer 42

HHV-6 | Parechovirus

Question 43

What CNS-disease causing viruses would you look for in someone just returning from an endemic region?

Answer 43

Japanese encephalitis Tick borne encephalitis West Nile virus Equine encephalitides

Question 44

Name a rare type of encephalitis caused by measles

Answer 44

Subacute sclerosing pan-encephalitis (SSPE)

Question 45

Which is better for PCR and antigen detection testing: stool or vomit, and why?

Answer 45

Stool is preferred as it gives a higher yield

Question 46

Name some viruses detectable in stool, causing diarrhoea and vomiting

Answer 46

``` Norovirus Rotavirus Adenovirus Sapovirus Astrovirus ```