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.
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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.

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Ability of different matrices to transmit African swine fever virus – Part 2

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.

For this week we continue with the summarized results from the Panel on Animal Health and Welfare (AHAW) of the European Food Safety Authority’s (EFSA) published opinion on the risk of African Swine Fever virus entering into non-affected areas of the EU. Several components were modeled as part of the overall modeling of the relative risk of ASF entering a non-affected area of the EU. Last week’s science page covered the first component, the Likelihood that a single farm delivery of a product will contain a dose of infectious ASFV, which is large enough to cause an infection in at least one pig on the farm (‘q’). In this follow up page we will look at the last two modeled components of the risk assessment.

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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.

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Temporal stability of swine movement networks in the U.S.

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. Dennis Makau from the VanderWaal lab is sharing a project on the importance of swine movement to identify farms with a high risk of disease outbreak.

Key Points

  • Animal movement is a key factor in the U.S. swine industry and is an important risk factor for disease transmission
  • Animal movement data combined with social network analysis can inform risk-based surveillance and control
  • Using production system movement data, it was possible to identify the time window of data needed to gauge connectivity and identify high-risk and high-spread farms
  • Using previous data up to two years old is still better than choosing randomly implemented interventions to manage disease spread, especially in cases of outbreaks transmitted via animal movements
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