PRRSPRRS Porcine Respiratory and Reproductive Syndrome Dr. Alex Ramirez Veterinary Diagnostic and Production Animal Medicine Iowa State University

PRRSPRRS General Overview

PRRSPRRS 3 PRRS THE most $$$ significant disease of swine –$560 million / year  $5.60 / pig marketed 1 –Comparison PRV $36 million / year Hog cholera $360 million / year –Outbreak estimated cost of $255 / sow 2 Continues to be a widespread cause of abortion and respiratory disease in Iowa and the United States 1 Neumann et al Holck and Polson 2003

PRRSPRRS 4 Karriker et al

PRRSPRRS 5 Relatively easy to do… Karriker et al

PRRSPRRS 6 Relatively easy to do… Hard to maintain… Karriker et al

PRRSPRRS 7 Characteristics of the Virus RNA virus –High mutation rate Enveloped –Does not survive well in the environment –Likes cold weather Open Read Fragments (ORF) –Total of eight (1a, 1b, 2, 3, 4, 5, 6, 7) –Usually only sequence ORF 5 Sequencing 600 bp (4%) out of ~15,000 bp

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PRRSPRRS 9 Characteristics of the Virus Constantly changing –“Quasi-Species” –European versus American strains  only 60-70% similar –Variable expression of disease severity PRRS “Lite” “Acute PRRS”  new disease or just a “stretch” Immunity induced by one “strain” does not protect against another “strain”

PRRSPRRS 10 Characteristics of the Virus Highly infectious –Takes only a few viral particles to infect a pig –Increasing dose  Quicker onset of disease Minimal influence on the ultimate severity of disease Transmission Potential : Low?? –Research  not very easy to spread –Field  variable experiences Body secretions including semen Farm-to-farm: neighborhood spread seems to occur

PRRSPRRS 11 PRRS transmission RouteID 50 SQ (parenteral)~10 1 Intranasal Artificial Insemination Oral Aerosol?? Hermann et al 2005

PRRSPRRS 12 Duration of shedding –Up to 5 months or longer –Experimental studies done in “clean” animals Mycoplasma prolongs PRRS-induced pneumonia Does mycoplasma prolong PRRS shedding? –Route Semen Oral secretions –Age Younger  longer Characteristics of the Virus

PRRSPRRS 13 PCR Results Cohort 1 (9 pigs) ID 2 wk4 wk6 wk8 wk10wk12 wk14 wk16 wk18 wk20 wk22 wk24 wk26 wk28 wk 1-152NEG POS NEGPOSNEGPOS 1-156NEG POS NEG POS 1-177POS 1-186POS 1-189POS NEGPOSNEG POS 1-191POS NEG POS 1-194NEGPOS NEG POS 1-196POS NEGPOS NEG POSNEG 1-220NEGPOS NEG POSNEG Karriker et al submitted 2007

PRRSPRRS 14 Available Tests FATS: Fluorescent antibody examination of frozen tissue PCR: Polymerase chain reaction RFLP: Restriction fragment length polymorphism VI: Virus Isolation Virus sequencing: Sequence analysis IHC: Immunohistochemistry ELISA: enzyme-linked immunosorbent assay IFA (NVSL): indirect fluorescent antibody test FFN: fluorescent focus neutralization assay VN: Virus neutralization

PRRSPRRS 15 Available Tests FATS: Fluorescent antibody examination of frozen tissue PCR: Polymerase chain reaction RFLP: Restriction fragment length polymorphism VI: Virus Isolation Virus sequencing: Sequence analysis IHC: Immunohistochemistry ELISA: enzyme-linked immunosorbent assay IFA (NVSL): indirect fluorescent antibody test FFN: fluorescent focus neutralization assay VN: Virus neutralization XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

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PRRSPRRS Respiratory

PRRSPRRS 18 PRRSv Diagnostics Lesions –Interstitial pneumonia Can visualize septa - fine pattern Tan discoloration - mottled or coalescing Rubbery texture Fail to collapse –Enlarged lymph nodes Sub-iliacs are best to view

PRRSPRRS 19 PRRSv Diagnostics

PRRSPRRS 20 Low virulent strain of PRRSv High virulent strain of PRRSv

PRRSPRRS 21 PRRSv-infected alveolar macrophages PRRSv-infected intravascular macrophages PRRSv infects and destroys macrophages in the lungs. Macrophages are important for removing bacteria and inflammatory debris from the lungs.

PRRSPRRS 22 All strains of PRRSv induce lymphadenopathy characterized by hyperplasia of lymphoid follicles

PRRSPRRS Reproductive

PRRSPRRS 24 Gestation age  Animal response –Weak born pigs –Stillborn pigs –Mummies –Early embryonic death  reduced litter size –Return to estrus –Abortion Boars –Shed in semen –Variable impact on semen quality Clinical Outcomes

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PRRSPRRS 26 PRRSv - Abortion due to Fetal Infection Gross Lesions: –Sow: typically none –Fetus: Diagnostically useful gross lesions are uncommon Meconium staining of fetal skin Umbilical cord edema with segmental hemorrhage Mesocolonic edema Perirenal edema

PRRSPRRS 27 PRRSv-Infected Fetuses

PRRSPRRS 28 Distribution of PRRSv-Infected Fetuses in a Litter ALL FETUSES IN A LITTER ARE TYPICALLY NOT INFECTED An average of 48.6% of the fetuses/litter infected Sow 10 –PRRSV-POSITIVE Fetuses 1, 2, 3, 4, 6 (#5 autolyzed) –PRRSV-negative fetuses 7, 8, 9, 10, 11, 12, 13 Sow 12 –PRRSV-POSITIVE Fetuses 5, 6, 7, 8, 9, 10 –PRRSV-negative fetuses 1, 2, 3, 4, 11, 12

PRRSPRRS 29 Assumptions: Litter of 12 50% fetal infection rate Confidence level for PRRSV detection in a litter with PCR Number of fetuses sampled per litter 99%6 97.5%5 95%4 90%4

PRRSPRRS 30 PRRSV Abortion Diagnostics PCR is the test of choice on fetal material –Extremely sensitive –Tissues and fetal thoracic fluid are equivalent –Samples from 1 positive fetus can be pooled with 7 negative fetuses (1:8) without loss of sensitivity –Limited impact of autolysis (can be detected following incubation at 37 o C [99 o F] for 4 days) Preferred diagnostic procedure: pool fetal thoracic fluid from 6 fetuses/litter for PRRSV PCR

PRRSPRRS 31 Clinical Outcomes Suckling and nursery pigs –Severe respiratory disease: interstitial pneumonia Rapid breathing, especially after stress Variable death loss –Often takes days longer to reach market compared to groups ahead or behind –Severity of infection diminishes greatly after 8 weeks of age unless affected by another agent M. hyo PCV2 SIV

PRRSPRRS Vaccination

PRRSPRRS Zuckermann, 1999 ParameterPRRSVPRV. Non-neutralizing7-14 daysNA antibodies Neutralizing antibodies> 28 days3-4 days Peak gamma 8-10 months1 month interferon levels Duration of shedding> 3-4 months3-4 weeks PRRSV Immunity Development

PRRSPRRS 34 CONTROVERSIAL (to say the least!!) –Everyone has a different opinion MLV vaccines –Several have been marketed –Patent infringement has resulted in only two available today: Boehringer Ingelheim PRRS MLV PRRS ATP –Variable benefit “Strain” differences Delay between vaccination and protective immunity  need at least 4 – 6 weeks Vaccination

PRRSPRRS 35 MLV vaccines (cont.) –Attenuated? Not safe in NAÏVE pregnant females –Abortions –Danish experience: farms receiving vaccine virus contaminated semen experienced reproductive disease Recombination? –Quarterly herd vaccination Booster heterologous protection? –Interfere with future diagnostics Vaccination

PRRSPRRS 36 Vaccination Sequence information –Does not predict virulence –Does not predict respiratory vs. reproductive –Does not predict cross-protection Do not use to select best vaccine –Does help as a epidemiological tool New vs. old Possible source? –Does serve as a reference for the future

PRRSPRRS 37 PRRSV Vaccination Killed vaccines –None commercially available today –Appear to booster existing immunity –Unclear efficacy in naïve animals Most likely of no value –Autogenous? Quasispecies Stability

PRRSPRRS 38 Based on the concept that the virus is shed 4-6 months after infection Infect/vaccinated incoming animals >3-4 months before entry Stop animal introductions for 4-6 months, then start introduction of negative animals Gilts most likely to transmit virus to their offspring Many programs developed off this strategy Produce PRRSV free offspring from sow herd Eliminate PRRSV reproductive failure Eradicate PRRSV without depop-repop Serum Inoculation

PRRSPRRS PRRS Management

PRRSPRRS 40 PRRS Management Exposure –Natural –Vaccine –Serum Herd closure –Target 200+ days Biosecurity –Location –Trucking  Wash and Bake –Pig flow –Needles Cycle

PRRSPRRS 41 Acknowledgements I would like to recognize the contribution of others to this presentation: –Dr. Brad Thacker –Dr. Locke Karriker –Dr. Pat Halbur

PRRSPRRS Questions?