Best of Leman 2019 #3: Three systems views on PRRS decreasing incidence

This is a favorite on the blog. Once a month, we are sharing with you a presentation given at the Allen D. Leman swine conference, on topics that the swine group found interesting, innovative or that lead to great discussions.

We can find all of the presentations selected from the previous years’ conferences on the blog here.

A few days ago, we shared a report that PRRS incidence decreased in naive breed-to-wean farms. Interesting questions were brought forward by our readers so this month, we are sharing three practitioners’ experiences with PRRS in their systems: Dr. Tara Donova with the Hanor company, Dr. Jay Miller with The Maschhoffs, and Dr. Pete Thomas from Iowa Select Farms.

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Comparison of PRRS incidence rate in status IV breeding herds during 2009-2019

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This post is from the MSHMP team looking at status IV farms and their PRRS incidence between the years 2009 and 2019. Quick reminder, in 2011, Holtkamp et al. defined status IV farms as PRRS-negative per their shedding and exposure status.

Key points

  • PRRS incidence rate in status IV farms varied significantly from 2009 to 2019.
  • The incidence rate in status IV farms during 2019 was one of the lowest on record and comparable to the one observed in 2013 and 2014; the years of the PED epidemic in the US.
  • PRRS incidence in status IV farms during 2019 was significantly lower than the one of 2015 and 2016 and marginally non-significant lower (p=0.07) than the one of 2018.
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Aerosol Detection and Transmission of PRRSv: What Is the Evidence, and What Are the Knowledge Gaps?

Aerosol transmission of Porcine Reproductive and Respiratory Syndrome virus is a major issue hog producers have had to deal with for several decades now. It encouraged the development of air filtration systems in farrow-to-wean farms as well as the isolation of high-value genetic lines in remote areas. This new publication, a collaboration between Dr. Arruda at the Ohio State University and Drs. Corzo and Torremorell from the University of Minnesota is a review of our knowledge of how PRRS is transmitted via aerosol.

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Characterization of Broadly Neutralizing Antibodies to PRRSV

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This week, Dr. Jordan Young from the late Dr. Murtaugh‘s lab shares his latest research project regarding the immune response against PRRS.

Key point

  • PRRSV antibodies were determined to be broadly binding, but only homologously neutralizing, suggesting a polyclonal response, involving multiple PRRSV specific antibodies might be necessary for PRRSV neutralization.
  • This means that vaccinations aiming to protect from infection likely need to involve exposure to multiple strains of PRRSV to induce a broad protective immunity, rather than relying on single-strain vaccines.
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PRRSv ORF5 difference from VR2332 by herd type

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This week, the MSHMP team assessed differences in ORF5 sequences compared to VR2332 based on the type of farm, the sequence was collected at.

Key points

  • Breeding herd sequences differ 8%-16% while in other herd types they differ 1%-15% from VR2332 at the ORF5 level. 
  • The larger nucleotide identity (%) range compared to VR2332 in growing pigs suggests a higher viral diversity within this group.
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