Aetiology pathogenesis and immunology of post-weaning multi-systemic wasting syndrome in pigs: genetic-environmental interactions

Lead Research Organisation: Royal Veterinary College
Department Name: Pathology and Pathogen Biology

Abstract

Post-weaning multi-systemic wasting syndrome (PMWS) is a common disease of young pigs in the U.K. It is extremely debilitating, causes considerable suffering and poor welfare, and has a high mortality of up to 20%. The disease was first recognised in 1991 and is now prevalent worldwide. Since over 1.2 billion pigs are reared annually for human consumption, then there are good commercial and ethical reasons why new diseases like PMWS should be controlled or eliminated to ensure a safe, humane and sustainable supply of pork, sausages and ham. At first scientists thought that PMWS was caused by a virus but they now realise that genetic and environmental factors must be involved, along with opportunistic secondary pathogens. This project proposes a unique interdisciplinary approach to investigate this endemic disease and will integrate modern scientific techniques from epidemiology, genetics, microbiology, pathology, molecular immunology and environmental science to identify why PMWS occurs, leading to new control methods. British pig farmers will be heavily involved in the project, thereby guaranteeing that pigs in Britain will be the first to benefit from this research, while collaboration with a major international pharmaceutical company will ensure that new veterinary products will be made available to pig farmers worldwide.

Technical Summary

Post-weaning multi-systemic wasting syndrome (PMWS) is considered to be a multifactorial disease, with porcine circovirus 2 (PCV2) suggested a necessary agent. Despite the fact that infected pigs seroconvert to PCV2, it is becoming increasingly evident that PCV2 is not the sole contributor, and that the host's genetic background, environment and opportunistic pathogen(s) play a crucial role in the pathogenesis of PMWS. Interestingly, infected pigs seem to harbour PCV2 in immune cells, despite no obvious viral replication or functional differences of infected cells. Once PMWS occurs, significant changes in the subpopulations of immune cells occur. These findings in PMWS-affected pigs suggest an inability to mount an effective immune response, although the mechanism(s) by which the immune system is altered is unclear. The present proposal is in three complementary parts. First, we will identify putative secondary pathogens in a case-control study on selected farms. This epidemiological study will also identify common environmental co-factors or triggers that lead to full clinical development of PMWS. Secondly, we will identify the molecular mechanisms of pathogenesis and the early replication effects of susceptible cells by using porcine-specific microarrays on cells generated from breeds with differing in susceptibility to PMWS. We will identify signalling pathways that are altered independently of cell type. By using cells generated from different breeds, we will identify molecules/pathways that are altered in specific breeds, and will aim to combine these analyses with subsequent genetic analysis. Thirdly, despite several attempts to re-create PMWS in vivo, no consistent experimental model of PMWS has been developed. Here, using the information generated in parts 1 and 2, we will attempt to develop an in vivo model of PMWS and use it to study the aetiology of PMWS including environmental and genetic risk factors and the involvement of secondary pathogens.

Publications

10 25 50

publication icon
Bae JK (2013) Risk factors associated with Lawsonia intracellularis in English pig farms. in Veterinary journal (London, England : 1997)

publication icon
Barbara Wieland (Author) (2008) Making sense of PMWS, PCV2, PCVD

 
Title Aetiology, pathogenesis and immunology of PMWS 
Description A voice-over of a presentation by Dr Barbara Wieland on the BPEX webpage, please see http://www.bpex.org.uk/downloads/300353/296959/PMWS%20RVC%20voice%20over%20presentation.ppsx 
Type Of Art Film/Video/Animation 
Year Produced 2008 
Impact no actual impacts realised to date 
URL http://www.bpex.org.uk/downloads/300353/296959/PMWS%20RVC%20voice%20over%20presentation.ppsx
 
Description Any kind of stress aids viral replication; no additional pathogen is required
Exploitation Route Improve housing conditions and creating stress-free environment can reduce costs of PCV2 infection, and may actually prevent it
Sectors Agriculture, Food and Drink

URL http://www.vettimes.co.uk/news/rvc-study-shows-environmental-stress-triggers-costly-pig-disease/
 
Description Analysis of BPEX PCV2 post-vaccination data
Amount £32,500 (GBP)
Organisation British Pig Executive BPEX 
Sector Charity/Non Profit
Country United Kingdom
Start 02/2009 
End 08/2009
 
Description Analysis of BPEX PCV2 post-vaccination data
Amount £32,500 (GBP)
Organisation British Pig Executive BPEX 
Sector Charity/Non Profit
Country United Kingdom
Start 02/2009 
End 08/2009
 
Description Identification of the T-cell dependent vaccine response to recombinant PCV-2 antigens
Amount £85,076 (GBP)
Organisation Royal Veterinary College (RVC) 
Sector Academic/University
Country United Kingdom
Start 09/2011 
End 09/2014
 
Description Identification of the T-cell dependent vaccine response to recombinant PCV-2 antigens
Amount £85,076 (GBP)
Organisation Royal Veterinary College (RVC) 
Sector Academic/University
Country United Kingdom
Start 09/2011 
End 09/2014
 
Title PMWS economic model calculator 
Description PMWS calculator to assess how much the disease cost to a specific farm and what are the most cost-efficient strategies on this farm. 
Type Of Material Database/Collection of data 
Year Produced 2013 
Provided To Others? No  
Impact No actual impacts realised to date 
URL http://www.bpex.org.uk/articles/303060
 
Title PMWS severity estimation sheet 
Description Estimation of Post-weaning Multi-systemic Wasting Syndrome (PMWS) severity that farmers can use for their farms. 
Type Of Material Database/Collection of data 
Year Produced 2011 
Provided To Others? No  
Impact No actual impacts realised to date 
URL http://www.bpex.org.uk/articles/300874
 
Description Calculator counts the cost of pig disease 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Primary Audience Participants in your research or patient groups
Results and Impact Press release to describe the the PMWS calculator which allows farmers to see just how much the disease, present in 99% of pig farms, has cost them. please see

no actual impacts realised to date
Year(s) Of Engagement Activity 2013
URL http://www.bbsrc.ac.uk/news/food-security/2013/130709-n-cost-of-pig-disease.aspx
 
Description From exotic to endemic: a new disease of pigs 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Description of severity indicators identified as part of the PMWS project Please see

no actual impacts realised to date
Year(s) Of Engagement Activity 2010
URL http://www.bbsrc.ac.uk/news/food-security/2010/101109-f-new-disease-pigs.aspx
 
Description New research suggests why some farms develop devastating pig disease 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Primary Audience Participants in your research or patient groups
Results and Impact New research funded by the Biotechnology and Biological Sciences Research Council, published today (8 July), has identified the factors that make some farms more likely to develop an economically devastating pig disease. The disease, Post Weaning Multi-systemic Wasting Syndrome (PMWS), is estimated to cost the UK pig industry £30M each year. The research could help to outline best practice husbandry to enable farmers to optimise animal welfare and maintain production. Please see

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
URL http://www.bbsrc.ac.uk/news/food-security/2011/110708-pr-devastating-pig-disease.aspx
 
Description PMWS and Risk Factors 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Primary Audience Public/other audiences
Results and Impact A leaflet produced in collaboration with BPEX to inform farmers about the risk factors related to PMWS occurrence on farms Research into Action Flyer, which can be found here:

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
URL http://www.bpex.org.uk/2ts/documents/RIA7PMWS.pdf
 
Description Pig disease research shows prevention strategy progress 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Article in "Veterinary Times" Article about latest PCV2 work funded through CEDFAS initiative Article in "Veterinary Times" (Vol. 44, No 14, page 4)

no actual impacts realised to date
Year(s) Of Engagement Activity 2014
URL http://www.xlvets.co.uk/press-articles/veterinary-times-vol-44-no-13
 
Description Pig wasting syndrom costing farmers millions 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Description of the economical findings related to PMWS Please see

no actual impacts realised to date
Year(s) Of Engagement Activity 2013
URL http://www.bbsrc.ac.uk/news/food-security/2013/130326-pr-pig-wasting-syndrome.aspx
 
Description Press coverage of PLOSOne article 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Primary Audience Media (as a channel to the public)
Results and Impact Press coverage of PLOSOne article

no actual impacts realised to date
Year(s) Of Engagement Activity 2014
URL http://www.farmingfutures.org.uk/blog/new-insights-pig-pmws-disease
 
Description Risk factors for PMWS: an on-going cross-sectional study in UK-pig farms 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Paper Presentation
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact Seminar at the AHVLA-RVC research day

no actual impacts realised to date
Year(s) Of Engagement Activity 2008
 
Description Scientists gain insights into pig disease which costs farmers millions 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Participants in your research or patient groups
Results and Impact Scientists gain insights into pig disease which costs farmers millions

no actual impacts realised to date
Year(s) Of Engagement Activity 2014