PRRS – Swine in Minnesota

Phylogenetic Structure and Sequential Dominance of Sub-Lineages of PRRSV Type-2 Lineage 1 in the United States

In a new study by Paploski et al., researchers from the VanderWaal lab delineated the phylogenetic structure within PRRSV Lineage 1, described past dynamics of different viral strains through quantifying viral population sizes across time, and identified antigenically relevant amino acid changes associated with each sub-lineage.

Key points

Lineage 1 of PRRSV-type 2, which is the most prevalent PRRSV lineage in the U.S., can be sub-divided into eight sub-lineages
We documented the cyclic emergence and turnover of different lineages and sub-lineages (about every 3 years) in the commercial pig population based on both sequence count data and estimated past viral population sizes inferred from genetic diversity through time.
The eight sub-lineages differed in key amino acid sites of the GP5 that are thought to be involved in the immune response to the virus. This lends further strength to the hypothesis that immune-mediated competition or selection may drive the emergence of new PRRSV sub-lineages in the U.S.

How many cases are we seeing of the new PRRS variant?

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.

As the MSHMP team continues to monitor the detection of the newly described PRRSv Lineage 1C RFLP 1-4-4 variant, they provide an update of the epidemiological curve of cases associated with this variant.

Best of Leman 2020: Forecasting PRRSV breaks based on biosecurity risks

This is our most popular series 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.

You can find all of the presentations selected from previous conferences on the blog here.

During the Carlos Pijoan SDEC symposium, Dr. Gustavo Machado shared insights on biosecurity practices at the farm level and the impact they can have on PRRS outbreaks. We hope you enjoy his talk.

PRRS incidence in status 4 sow farms

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 updates a valuable statistical parameter: the PRRS incidence in status 4 status 4 sow farms. As a reminder, status 4 farms are defined as negative for PRRS in both exposure and shedding status.

Key Points

In the last 13 years, on average 9.3% (Range 3.2% – 20.3%) of status 4 farms have had a PRRS outbreak, with an apparent cyclical peak at around 10% every 2-3 years.
The cumulative incidence of the current MSHMP year (July 2020 to May 2021) for status 4 farms is 9.9%.
PRRS incidence in status 4 farms during the current MSHMP season is not higher than the ones observed in the previous MSHMP seasons.

Modeling the transmission and vaccination strategy for PRRS virus

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 Science Page is written by Dr. Galvis et al. from the Machado lab at North Carolina State University. They report their results with modeling PRRSv transmission in situations where vaccines can be used as mitigation tools.