Unit 4 - PRRS

Question 1

T/F: PRRS is the most expensive disease affecting US swine

Answer 1

True

Question 2

What type of virus is the PRRS virus?

Answer 2

an enveloped RNA virus

Question 3

T/F: Since the PRRS virus is an enveloped virus, this means that it does not survive well in the environment.

Answer 3

True- however it is relatively stable in cold weather

Question 4

Usually what open reading frame of PRRS virus is sequenced?

Answer 4

ORF 5

Question 5

80% of the PRRSv genome is ORF __.

Answer 5

1

Question 6

What is the PRRSV strain that is found in North America?

Answer 6

PRRSV-2

Question 7

What are the epidemiolgically relevant characteristics of PRRSV?

Answer 7

They are constantly changing
Pig genetic resistance is described
Immunity induced by one ‘strain’ does not fully protect against another ‘strain’

Question 8

T/F: The most infectious route of PRRSV transmission is via the aerosol route

Answer 8

True - Aerosol > SQ, IM > Intranasal > Artificial Insemination > Oral

Question 9

What is the epidemiologic triad for PRRS?

Answer 9

Pig, PRRSv, and Environment

Question 10

When can antibodies begin to be detected via ELISA post PRRSv infection?

Answer 10

Beginning at week 1, ~90% at 2 weeks

Question 11

When is PRRSv at its peak in blood? What test can detect it here?

Answer 11

Peak at 1 week - detected by PCR

Question 12

How long do PRRSv infected pigs shed the virus?

Answer 12

From day 1 to approximately 3 months

Question 13

Where does PRRSv live in the body?

Answer 13

Lung, tonsils, and lymph nodes - detectable by PCR

Question 14

How is PRRSv transmitted?

Answer 14

Inhalation, ingestion, coitus, semen, bite wounds, or needles

Question 15

Where does PRRSv replicate?

Answer 15

In mucosal, pulmonary, or regional macrophages

Question 16

When do viral PRRSv titers peak?

Answer 16

At 7-14 day

Question 17

Where anatomically does prolonged infection occur in cases of subclinical PRRSv?

Answer 17

the lungs and lymphoid tissues

Question 18

How do sows clinically present with PRRSv?

Answer 18

Increased abortion, premature farrowing with weak liveborn pigs, increased incidence of stillborns, and increased incidence of autolyzed fetuses

Question 19

How do neonatal pigs clinically present with PRRSv?

Answer 19

Pneumonia, increased mortality

Question 20

How do growing pigs clinically present with PRRSv?

Answer 20

Pneumonia, increased concurrent bacterial infections, and increased mortality

Question 21

How do boars clinically present with PRRSv?

Answer 21

Fever, and morphological changes to semen

Question 22

PRRSv induces lymphadenopathy characterized by what?

Answer 22

Hyperplasia of lymphoid follicles

Question 23

There are a lot of available tests for detection of PRRSv. What are the most common/preferred ones?

Answer 23

PCR, virus sequencing, ELISA, and IHC

Question 24

What does PCR for PRRSv measure?

Answer 24

The level of viremia and shedding

Question 25

What is the purpose of virus sequencing for PRRSv?

Answer 25

Epidemiological investigations

Question 26

What is the purpose of ELISA testing for PRRSv?

Answer 26

Investigate virus exposure

Question 27

What is the purpose of IHC testing for PRRSv?

Answer 27

To double-check an unexpected positive result on ELISA

Question 28

What is the point of virus neutralization?

Answer 28

To determine the protective immune response

Question 29

What clinical signs from a sow farm can be indicative of PRRSv?

Answer 29

Sows off feed, increased abortions, increased mummified fetuses + stillbirths, increased pre-weaning mortality

Question 30

What clinical signs form growing pigs can be indicative of PRRSv?

Answer 30

Increased mortality, poorer growth efficiency Increased severity of other diseases Respiratory disease

Question 31

Does PCR or ELISA detect for evidence of exposure?

Answer 31

ELISA

Question 32

What samples can be used for PCR detection of PRRSv?

Answer 32

Blood, processing fluids, oral fluids, semen | Lungs, tonsils, lymph nodes

Question 33

What samples can be used for ELISA detection of PRRSv?

Answer 33

Blood, processing fluids, oral fluids

Question 34

What general lesion will you find in pathology of the lungs in a PRRSv patient?

Answer 34

Interstitial pneumonia

Question 35

What samples are used for individual pig sampling??

Answer 35

Serum, blood swab, and tonsil scraping

Question 36

What samples are used for population-based sampling?

Answer 36

Oral fluids, processing fluids, and production data

Question 37

Is individual or herd monitoring more practical and cheaper?

Answer 37

Population-based sampling

Question 38

What are the goals for control of PRRSv?

Answer 38

Maintain as PRRSv-positive, limiting production impact of outbreaks

Question 39

What are the goals for elimination of PRRSv?

Answer 39

Eliminate the virus and maintain as a PRRSv-negative herd

Question 40

What are the key points for PRRS control?

Answer 40

Build herd immunity | Bio-management practices

Question 41

How is herd immunity against PRRSv built?

Answer 41

Immunize incoming gilts Immunize sows Temporarily interrupt gilt introduction

Question 42

What is the challenge with immunization of PRRSv?

Answer 42

PRRsv is a moving target to vaccine development

Question 43

What are the immunologic solutions to the PRRSv moving target challenge?

Answer 43

An attenuated virus vaccine Live-virus inoculation Killed virus vaccine

Question 44

Why would you want to 'classify herds; for PRRSv?

Answer 44

Allows for vet-to-vet communication Market Epidemiological studies Track industry progress over time

Question 45

PRRSv is a highly ______ virus, causing important economic impact in IA, USA and the worldwide pig industry. It is transmitted _____ and ______.

Answer 45

mutagenic | Directly and indirectly

Question 46

T/F: It is possible to eliminate PRRSv without depopulation.

Answer 46

True

Question 47

Successfully managing PRRSv depends on what?

Answer 47

Adjusting gilt acclimation, gilt flow, and herd immunization

Question 48

What is the main key for control and elimination of PRRSv?

Answer 48

Diagnostic monitoring