Evaluation of oral fluid as an aggregate sample for early detection of ASF

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.

Since ASF has been found in the Dominic Republic last week, swine producers are concerned about it spreading into the United States. Early detection would be essential to ensure a rapid response and containment of the disease. This week, the MSHMP team shares the summary of a Canadian study looking at using oral fluids as a tool to diagnose ASF.

Key Points

  • Oral fluid samples may be used as a low labor, cost effective alternative sample source for rapid detection of ASFV during ASF surveillance.
  • ASFv genome was detected in oral fluids at low-to-moderate levels as early as 3-5 days post infection, before clinical symptoms started. 
  • Further research is needed to understand limitations and best practices of oral fluid sampling for ASFv
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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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Histological Lesions and Replication Sites of PCV3 in Naturally-Infected Pigs

A team of researchers led by Dr. Fabio Vannucci investigated the lesions associated with a natural infection by Porcine Circovirus 3. They focused their study on histological lesions as well as replication sites to get a better understanding of this virus’ pathology. The article is available in open access on the journal’s website.

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Are mosquitoes a risk for ASF?

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 tip summarized a publication by Qin et al. regarding the risk of mosquitoes carrying and transmitting African Swine Fever virus.

Key Points

  • African swine fever (ASF) continues to pose a large risk in the absence of safe and effective ASF vaccines
  • There is evidence indicating that mosquitos may be a possible ASF vector 
  • Mosquitos captured at ASF positive farms had DNA extracted and tested for ASF with no positive results
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Temporal stability of swine movement networks in the U.S.

Efficient and highly effective control of infectious diseases can be achieved by targeting interventions towards farms that are highly connected “super-spreaders” in animal movement networks. However, from an implementation standpoint, it is unclear how much movement data is required to gain an accurate picture of farm connectivity, nor how quickly movement networks change over time. For example, can movement data from last year be used to identify potential super-spreaders this year? How often do such analyses need to be updated? Answering these questions is key to moving from science to practice in terms of successful deployment of network-based targeted control strategies in swine production systems. In this study, Dr Dennis Makau and the VanderWaal lab aim to answer these questions for production systems in the United States.

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