What is new regarding swine central nervous system diseases?

Podcasts are a perfect way to get caught up with new swine information! We are presenting you the latest episode from “At The Meeting… Honoring Dr. Bob Morrison” in collaboration with SwineCast.

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Characterization of Broadly Neutralizing Antibodies to PRRSV

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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Focusing on the grow/finish stages of production to better control PRRS, the new challenge of the swine industry?

Should we redirect our research efforts to focus on PRRS prevention and control in growing and finishing pigs? This was the call for action made by Dr. Montse Torremorell, Associate Professor at the University of Minnesota when she opened the special session “Grow/finish phase of production: What are we learning and implications for making progress on PRRS control.” sponsored by Boehringer Ingelheim during the North American PRRS Symposium this past weekend in Chicago. Torremorell argued that if the swine industry wants to advance regional PRRS control, more emphasis needs to put on preventing and controlling PRRS in growing pigs.

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NHF: Enteroids as in vitro model for ileitis

Our new contribution to the National Hog Farmer was written by Dr. Talita Resende, a PhD candidate at the University of Minnesota under the supervision of Dr. Connie Gebhart. Talita’s research focuses on swine ileitis and models to better understand its pathogen: Lawsonia intracellularis. Today, she explains how she uses enteroids.

The small intestine is largely responsible for nutrient digestion and absorption in the gastrointestinal tracts of pigs, but it is also an ideal colonization site for enteric pathogens. The investigation of the interactions between host and enteric pathogens can be conducted in vivo, or in vitro, with advantages and disadvantages for each of the models. Enteroids, small intestinal organoids, represent a new in vitro approach to investigate those interactions. But why are enteroids a new approach and what are their advantages in comparison to the current models?

Enteroids are three-dimensional structures originated from embryonic stem cells, induced pluripotent cells or adult stem cells from intestinal tissue. Therefore, they present all the cell types and a structural organization similar to crypts and villi found in the small intestine. This complex structure offers ideal conditions to investigate the mechanisms by which Lawsonia intracellularis causes proliferative enteropathy – also known as ileitis – in pigs.

A constellation of strains co-circulate in pigs during influenza epidemics

This recent publication in Nature comes from the Torremorell’s lab and aims at answering the question of the number of strains circulating in pigs during an influenza outbreak and how genetically different they may be. The full article is available in open access, click on the banner below to access it.

Constellation influenza banner Torremorell

To answer the question of multiple strains of influenza in pigs, the group followed a cohort of 132 pigs placed in a 2,200-head a wean-to-finish barn, endemic for influenza. All the pigs originated from the same sow farm . The history of past influenza episodes did not include any information regarding the strain of viruses circulating in the barn. Nasal swabs were collected for each individual pig and were tested in the laboratory by PCR.

Results from this study showed that:

  • Only 2 pigs out of 132 tested negative every week during the entire duration of the study.
  • Around 88% of the pigs tested positive for influenza more than once.
  • 20.5% of pigs were positive for influenza at weaning.
  • Weekly influenza prevalence ranged between 0% and 65%.
  • 3 different viral groups were identified VG1, VG2, and VG3.
  • Groups belonged to the swine H1-gamma, H1-beta and H3-cluster-IV influenza A respectively. (Here is a review of the H1 genetic clades and one of the H3 genotype patterns)

The figure below shows the genetic make up of the influenza strains isolated each week, the viral group each genetic segment belonged to and the number of times this specific combination was found.

For example, the second line can be interpreted as: during week one, one sample in which 10 sequences were recovered, had influenza virus with segments 1, 2, 3, 4, 5, and 7 belonging to the Viral Group 1 (H1 gamma) and segments 6 and 8 were from Viral groups 1 and 3.

Influenza constellation Torremorell

In conclusion, this study shows that influenza infections in pigs after weaning and under field conditions are complex. The influenza virus genome is diverse and changes rapidly. Prolonged persistence of influenza viruses in pigs could be the result of multiple influenza epidemic events that take place repeatedly over time or the re-infection with influenza viruses that are closely related to each other.


Swine play a key role in the ecology and transmission of influenza A viruses (IAVs) between species. However, the epidemiology and diversity of swine IAVs is not completely understood. In this cohort study, we sampled on a weekly basis 132 3-week old pigs for 15 weeks. We found two overlapping epidemic events of infection in which most pigs (98.4%) tested PCR positive for IAVs. The prevalence rate of infection ranged between 0 and 86% per week and the incidence density ranged between 0 and 71 cases per 100 pigs-week. Three distinct influenza viral groups (VGs) replicating as a “swarm” of viruses were identified (swine H1-gamma, H1-beta, and H3-cluster-IV IAVs) and co-circulated at different proportions over time suggesting differential allele fitness. Furthermore, using deep genome sequencing 13 distinct viral genome constellations were differentiated. Moreover, 78% of the pigs had recurrent infections with IAVs closely related to each other or IAVs clearly distinct. Our results demonstrated the molecular complexity of swine IAVs during natural infection of pigs in which novel strains of IAVs with zoonotic and pandemic potential can emerge. These are key findings to design better health interventions to reduce the transmission of swine IAVs and minimize the public health risk.