Unit 4 - PRRS Flashcards
T/F: PRRS is the most expensive disease affecting US swine
True
What type of virus is the PRRS virus?
an enveloped RNA virus
T/F: Since the PRRS virus is an enveloped virus, this means that it does not survive well in the environment.
True- however it is relatively stable in cold weather
Usually what open reading frame of PRRS virus is sequenced?
ORF 5
80% of the PRRSv genome is ORF __.
1
What is the PRRSV strain that is found in North America?
PRRSV-2
What are the epidemiolgically relevant characteristics of PRRSV?
They are constantly changing
Pig genetic resistance is described
Immunity induced by one ‘strain’ does not fully protect against another ‘strain’
T/F: The most infectious route of PRRSV transmission is via the aerosol route
True - Aerosol > SQ, IM > Intranasal > Artificial Insemination > Oral
What is the epidemiologic triad for PRRS?
Pig, PRRSv, and Environment
When can antibodies begin to be detected via ELISA post PRRSv infection?
Beginning at week 1, ~90% at 2 weeks
When is PRRSv at its peak in blood? What test can detect it here?
Peak at 1 week - detected by PCR
How long do PRRSv infected pigs shed the virus?
From day 1 to approximately 3 months
Where does PRRSv live in the body?
Lung, tonsils, and lymph nodes - detectable by PCR
How is PRRSv transmitted?
Inhalation, ingestion, coitus, semen, bite wounds, or needles
Where does PRRSv replicate?
In mucosal, pulmonary, or regional macrophages
When do viral PRRSv titers peak?
At 7-14 day
Where anatomically does prolonged infection occur in cases of subclinical PRRSv?
the lungs and lymphoid tissues
How do sows clinically present with PRRSv?
Increased abortion, premature farrowing with weak liveborn pigs, increased incidence of stillborns, and increased incidence of autolyzed fetuses
How do neonatal pigs clinically present with PRRSv?
Pneumonia, increased mortality
How do growing pigs clinically present with PRRSv?
Pneumonia, increased concurrent bacterial infections, and increased mortality
How do boars clinically present with PRRSv?
Fever, and morphological changes to semen
PRRSv induces lymphadenopathy characterized by what?
Hyperplasia of lymphoid follicles
There are a lot of available tests for detection of PRRSv. What are the most common/preferred ones?
PCR, virus sequencing, ELISA, and IHC
What does PCR for PRRSv measure?
The level of viremia and shedding
What is the purpose of virus sequencing for PRRSv?
Epidemiological investigations
What is the purpose of ELISA testing for PRRSv?
Investigate virus exposure
What is the purpose of IHC testing for PRRSv?
To double-check an unexpected positive result on ELISA
What is the point of virus neutralization?
To determine the protective immune response
What clinical signs from a sow farm can be indicative of PRRSv?
Sows off feed, increased abortions, increased mummified fetuses + stillbirths, increased pre-weaning mortality
What clinical signs form growing pigs can be indicative of PRRSv?
Increased mortality, poorer growth efficiency
Increased severity of other diseases
Respiratory disease
Does PCR or ELISA detect for evidence of exposure?
ELISA
What samples can be used for PCR detection of PRRSv?
Blood, processing fluids, oral fluids, semen
Lungs, tonsils, lymph nodes
What samples can be used for ELISA detection of PRRSv?
Blood, processing fluids, oral fluids
What general lesion will you find in pathology of the lungs in a PRRSv patient?
Interstitial pneumonia
What samples are used for individual pig sampling??
Serum, blood swab, and tonsil scraping
What samples are used for population-based sampling?
Oral fluids, processing fluids, and production data
Is individual or herd monitoring more practical and cheaper?
Population-based sampling
What are the goals for control of PRRSv?
Maintain as PRRSv-positive, limiting production impact of outbreaks
What are the goals for elimination of PRRSv?
Eliminate the virus and maintain as a PRRSv-negative herd
What are the key points for PRRS control?
Build herd immunity
Bio-management practices
How is herd immunity against PRRSv built?
Immunize incoming gilts
Immunize sows
Temporarily interrupt gilt introduction
What is the challenge with immunization of PRRSv?
PRRsv is a moving target to vaccine development
What are the immunologic solutions to the PRRSv moving target challenge?
An attenuated virus vaccine
Live-virus inoculation
Killed virus vaccine
Why would you want to ‘classify herds; for PRRSv?
Allows for vet-to-vet communication
Market
Epidemiological studies
Track industry progress over time
PRRSv is a highly ______ virus, causing important economic impact in IA, USA and the worldwide pig industry. It is transmitted _____ and ______.
mutagenic
Directly and indirectly
T/F: It is possible to eliminate PRRSv without depopulation.
True
Successfully managing PRRSv depends on what?
Adjusting gilt acclimation, gilt flow, and herd immunization
What is the main key for control and elimination of PRRSv?
Diagnostic monitoring
