Ch 29 molecular diagnostics

Question 1

What is targeted for Equine influenza virus isolation by PCR?

Answer 1

hemagglutinin
nucleoprotein
matrix gene
**are commonly targeted genes

Question 2

What is the sample of choice for testing for EHV-1 and EHV-4?

Answer 2

nasal or nasopharyngeal swab virus isolation/PCR

Question 3

Streptococcus equi subsp equi culture may be unsuccessful for what reasons?

Answer 3

–during incubation & early clinical phases of infection
-presence of other Beta-hemolytic streptococci especially S. equi subsp zooepidemicus

Question 4

What is one of the pitfalls in using PCR as a diagnosis?

Answer 4

inability to distinguish between live and nonviable organisms

Question 5

PCR for Strep equi subsp equi should be considered in what scenerios?

Answer 5

-detect asymptomatic carriers
-establish the S. equi infection status of asymptomatic horses
-determine the success of elimination of S. equi from the guttural pouch

Question 6

What is considered the gold standard diagnosis of Rhodococcus equi?

Answer 6

culture of the organism from TTW fluid

Question 7

PCR for what gene of R equi in a TW fluid sample from a foal with pneumonia can be considered diagnostic?

Answer 7

Vap A gene

Question 8

PCR for testing of neural tissue is useful when?

Answer 8

for post mortem testing

Question 9

WNV encephalitis diagnostics

Answer 9

-one or more of the following– isolation of WNV from blood, CSF or tissue
-four fold increase in plaque reduction neutralization antibody titers on paired serum samples taken two weeks apart
-detection of IgM antibody to WNV by IgM capture ELISA

Question 10

Which serotype of EHV-1 is associated with neurologic outbreaks?

Answer 10

D752 genotype