Chart 3 description: PRRS incidence rate by status at break

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.

In this Friday’s article the Morrison Swine Health Monitoring Project helps example Chart 3: PRRS incidence rate by status at break, data that can be challenging to interpret, but also valuable to understand.

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Updated epidemiological curve of cases associated with the new PRRS Lineage 1C RFLP1-4-4 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 are updating the epidemiological curve of cases associated with this variant.

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Post-epidemic dynamics of PEDV in the United States: Current trends and patterns

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 is sharing what they are observing regarding Porcine Epidemic Diarrhea virus in the US. What are the trends and patterns emerging years after the epidemic?

Main Points 

  • Since July 2014, the number of PEDV yearly outbreaks reduced both numerically and in geographical distribution.
  • PEDV outbreaks occur seasonally, with most cases being detected during winter.
  • Spatial-temporal clusters of PEDV outbreaks were detected, most of which occurred prior to 2019.

Porcine epidemic diarrhea (PED) is a swine enteric viral disease first documented in the U.S. swine population in 2013, at which time it sparked a major epidemic. Since then, PEDV has persisted in the U.S. breeding herd with low incidence during the post-epidemic period. Despite continued monitoring and surveillance, there is minimal research and understanding of the endemic phase of PEDV in the country. Our objective was to characterize PEDV in the U.S. breeding herd in the post epidemic period (spatial-temporal distribution of cases and associated factors). 

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

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.

Keypoints

  • Lineage 1 PRRSv, 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) 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 GP5 amino acid sites that are thought to be involved in the immune response to the virus.
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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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