PROGRAMME - British Society of Animal Science

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208 Aetiology, pathogenesis and immunology of post-weaning multi-systemic wasting syndrome in pigs: genetic environmental interaction. Results so far D.Werling 1 , P. Alarcon 1 , C. Browne 1 , T. Demmers 1 , S. Gauss 1 , D.Armstrong 2 , D. Pfeiffer 1, A.Nevel 1 , B.Schmidt 1 , C.Wathes 1 , M. Velasova 1 , B.Wieland 1 1 Royal Veterinary College, London, UK, 2 BPEX, Stoneleigh Park, Kenilworth, UK Email: dwerling@rvc.ac.uk Background Post-weaning multi-systemic wasting syndrome (PMWS) causes major economic losses for the world-wide pig industry and severity of clinical signs and economic impact vary considerably between affected farms. PMWS emerged as a significant disease affecting pig production in the 1990s although the causal agent, porcine circovirus type 2 (PCV2), and the disease itself, had existed in swine for many years prior to this. In the United Kingdom the first outbreaks of the disease were reported in Northern Ireland in 1997 and in the south east of England in late 1999. Subsequently, the disease moved northward and reached Scotland in 2002. A telephone survey with veterinary practitioners in England and Wales indicated that between 18 and 20% of the holdings were affected by PMWS and PDNS by 2000 and a retrospective cohort study in England and Wales resulted in 83% of reporting British farmers having observed clinical signs of PMWS in their farm between 2000 and the end of 2003. Reports based on diagnostic sample submissions indicate a peak of the epidemic in 2002–2003 with significant decrease in the following years. During these early years of the epidemic stage, the cost of the disease has been estimated at £35 million per year for the United Kingdom and between €562 and 900 million across the European Union. PCV2 is a small and rather simply organized virus and expresses only few proteins. Therefore, it was expected that the factor(s) triggering PMWS should be easily identified, but more than one decade of PCV research has not yet singled out a molecule inducing the disease onset. Typically, the disease affects pigs aged between 8 and 15 weeks and the most frequent clinical signs are wasting, skin pallor, respiratory distress, diarrhoea, jaundice and enlarged lymph nodes. Economic losses are caused through increase in post-weaning mortality, reduced growth rates, increased feed conversion ratios, and secondary infections resulting in increased management and treatment costs. However, since its first occurrence, the disease appears to have evolved from epidemic to endemic status and farmers and veterinary practitioners have reported changes in the clinical pictures and severity of PMWS observed on farms. The highly beneficial effects of the PCV2 vaccines, which have been in use since 2008, highlight that the role of subclinical disease might have been underestimated over the last five years. Even farms that had minor PMWS problems seem to have been able to significantly increase their overall productivity since PCV2 vaccination. The present paper gives a progress report on aspects of a collaborative project aimed to understand the current PMWS/PCV2 situation in England, to identify risk-factors associated with the outbreak of PMWS on farms, to potentially identify key-genes being affected by the virus in the host, and to assess the genetic as well as the environmental factors potentially contributing to the occurrence of PMWS. Unravelling the molecular features of PCV and the channels through which the virus interacts with its host are key to manage, prevent and treat PMWS and other PCV-associated diseases. Methods An initial investigation into samples obtained and stored during an outbreak of PMWS on a large commercial farm showed that the virus was present on the farm a long time before the actual outbreak of the disease (1). The investigations also identified a potential genetic component as well as indicated a switch from a PCV2a to a PCV2b genotype of the virus. Complementary strategies of epidemiology, immunology and animal husbandry were applied to identify on-farm risk factors for PMWS using a cross-sectional study on 147 farms. Nearly 6000 blood-samples were analysed for a variety of porcine pathogens, as well as post-mortems performed to verify the presence of PCV2 (2). A microarray approach was applied to assess the changes induced by the current UK PCV2 isolate on different immune cell subsets as well as bone-marrow cells. The information derived in part 1 (Epidemiology) and part 2 (Immunology) of the project then informed part 3 (reproduction of disease under controlled conditions). Results to date: There is no doubt that PCV2 is endemic in the UK, with 99.8% of farms being tested positive for PCV2 (2). After developing a new scoring scheme for PMWS-affected farms (3) as well as identifying risk factors on farms for the occurrence of PMWS (4), we were able to show that the virus is not inducing a pathogen specific signature in infected cell types. Indeed, PCV2 is inducing very cell specific changes, all mounting in a suppression of immune responses, pot6entially pathing the field for secondary infections (Schmidt et al., in preparation). The first trials to reproduce the disease under controlled conditions, using the risk-factor identified are currently on their way, and the first results indicate the successful reproduction of PMWS. Available results will be presented and discussed at the meeting. Acknowledgements This project is funded by the BBSRC CEDFAS Initiative, with industrial support from Pfizer Animal Health, BioBest Ltd. And BPEX. References 1. Porcine circovirus type 2 (PCV2) infection before and during an outbreak of post-weaning multi-systemic wasting syndrome (PMWS) on a pig farm in the UK. Wieland, B., Werling, D., Nevel, A., 19 , Grierson, S., Rycroft, A., Demmers, T.G., Cook A., Done S.H., Armstrong D., and Wathes, C.M. Vet Record, in press 2. Prevalence of endemic pig diseases in England: an overview six months into a large-scale cross-sectional study on Post- Weaning Multi-systemic Wasting Syndrome (PMWS). B. Wieland, P. Alarcon, M. Velasova, A. Nevel, H. Towrie, D. Pfeiffer, C. Wathes, D. Werling. The Pig Journal 2010; 63: 20-23 3. Assessment and quantification of post-weaning multi-systemic wasting syndrome severity at farm level. Alarcon P, Velasova M, Werling D, Stärk KD, Chang YM, Nevel A, Pfeiffer DU, Wieland B. Prev Vet Med. 2011 Jan 1;98(1):19-28. 4. Farm level risk factors associated with severity of post-weaning multi-systemic wasting syndrome. Alarcon P, Velasova M, Mastin A, Nevel A, Stärk KD, Wieland B. Prev Vet Med. 2011 Sep 1;101(3-4):182-91.
207 Linking science and skills in agriculture R Longthorp LKL Farming . Burland . Holme Road . Howden . Goole . Yorkshire, UK Email: rlongthorp@longthorp.com Is there a need for a link between science and skills? If there is a need, then is there a link in place and is it effective? The answer to the first question is unequivocally yes. There has to be a clear and effective link between science and skills if real value is to be realised and delivered to industry and society from science and technology. The primary function of applied science should not be the science per se, but the application of it. Not what the research shows but what the research allows to happen as a consequence. If nothing positive happens as a consequence of the research or if the full potential of the research is not realised then time and resource have been wasted and value lost. Would scientists want to be remembered for great science or great impact? But scientists are, for the most part, totally dependent on others to help and apply their science - the extension officers and farmers. By the same token, the farmers and extension officers rely upon the skills of the scientist to carry out good quality research. There is also a joint responsibility to determine just what needs researching. It is in the common interest, therefore, that all within the triumvirate of applied scientists, extension officers and farmers are not only competent but also constantly working to maintain and improve their contemporary competence and professional standards. By improving skills across the piece, developing stronger relationships with those upstream and downstream and by targeted research and its effective application, more value can be added to the whole process. Adding synergistic value through collaborative and complementary working is not new and there is a parallel with existing collaborative models. The concept and benefits of value added through integrated supply chains has been recognised for some time by both economists and those operating in industry alike. The value of the (integrated) whole can be significantly greater than the value of the sum of the parts. The same should be true of an integrated approach to science, extension and skills. Integration should lead to better directed science, better translated science and better implemented science. The result is that more total value is generated, part of which can be ploughed back into further research, technology, extension and skills and even more value added. Does the term “Technology Value Chain” exist? Perhaps it should do. Perhaps it should be implicit in all Supply Value Chains. Whilst most agricultural sectors can claim to have a science, R&D and extension offer, only a few could claim to have a skills offer that is integrated into the mix. The pig industry is one of these but even this would have to be described as “work in progress”. Most of the effort has thus far been concentrated on technical skills at farm level. Recently more attention has been paid to leadership and management skills. This has given a quantum step in terms of achieving behavioural change. Lessons can be learnt by the science fraternity by not just looking at technical skills but also incorporating those other soft, management and leadership skills necessary to get the best out of industry’s limited resources. Furthermore, as with primary production, there is also a need to help develop the higher level skills and professional standing and recognition of the scientists so that applied agricultural science is seen as a career of choice. Looking at the broader picture, it is encouraging to note that the Agriculture and Horticulture Development Board are starting to recognise the importance of not only skills but also the relationship between science, extension and skills. However, a primary pre-requisite for this initiative to gain traction is for all sectors to have comprehensive skills offers. In the meantime the pig industry can hopefully demonstrate what value is possible by further refining its integrated offer of science, extension and skills. 20
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PROGRAMME - British Society of Animal Science

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