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Porcine Circovirus Diseases project making good progress

by 5m Editor
10 September 2007, at 2:04pm

EU - The project management team of the current multidisciplinary and multinational EC-funded research project on porcine circovirus diseases (STREP: PCVD www.pcvd.org) and the linked EC-funded PCVD Specific Support Action (SSA pcvd-ssa.vri.cz/) would like to highlight areas of the progress to date within these projects and reaffirm the need for good laboratory-based diagnosis of PCVDs to avoid misdiagnosis of African Swine Fever and/or Classical Swine Fever.

The PCVD STREP and SSA will shortly be entering year 3 of a four year programme of action. Significant progress has been made in the harmonisation of diagnostic methodologies for PCVD across EC member states and North America, the epidemiology of PCVD, the cellular and molecular mechanisms and viral interactions involved in development of PCVD and, most importantly, control of PCVDs.

The distribution and harmonisation of reagents and protocols for diagnosis of PCVDs and the training of young European scientists in their use has been very successful with, to date, 17 young scientists from 11 countries across EU member states participating in training exchange programmes. Harmonisation of reagents and protocols is on-going with ring trials completed on virus isolation and quantification, detection and quantification of antibody titres to PCV2, quantitative PCR detection of PCV2, immunohistochemical detection and quantification of PCV2 in tissues, and detection and scoring of PCVD lesions in tissue samples. This work will continue with 6 training exchanges planned in the next 12 months and additional ring trials incorporating laboratories and samples from North America. The important training of young scientists working on diseases of swine and harmonisation of reagents through the STREP/SSA is expanding into a global effort and will contribute to the important differential diagnosis of PCVD/ASF/CSF.

The work being carried out in the multidisciplinary STREP on "natural" genetic resistance/susceptibility of swine to PCVD using techniques including SNP analysis, in conjunction with the work on virus/swine cellular interactions at the molecular level using differential display and microarray analysis and the intensive studies on the immune functions of swine following infection with PCV2 are now coming together in the final stages of this project. Using microsatellite markers in conjunction with samples from extensive cohort studies on PCVD-affected and non-affected pigs from all over Europe a candidate region on the pig genome which is important in disease development has been identified. This region is now being subjected to SNP analysis. It is of interest and importance that we now know from separate, but related studies within the multidisciplinary STREP, that this region of the pig genome encodes for proteins that significantly differ in their interactions with PCV2 (pathogenic) and PCV1 (non-pathogenic) proteins. These proteins are important in the pig immune response to PCV2 infection and are also linked to the trans-cellular traffic of PCV2 in the pig. These findings emphasise the importance of a collaborative, multidisciplinary approach to this type of research where the results generated by one discipline can be tied to results generated by other disciplines to give a complete picture.

Most importantly, work within the EC-funded STREP has made significant advances towards the eventual control of PCVDs, having built upon previous important work completed by STREP partners before the consortium was formed. Trials on nutritional mechanisms of reducing PCV2 viral load in pigs, which can reduce the clinical impact of PCVD have been successfully completed. The consortium hase been, and continues to be, active in the development of PCV2 vaccines. Extensive experimental and field trials on candidate and commercial PCV2 vaccines have been, or are being, completed in EU member states and North America with outstanding results being reported. Indeed it would appear that in some cases in North America and Europe the levels of mortality and economic losses post-vaccination are lower than those seen before the outbreaks of PCVD, indicating that "sub-clinical" PCV2 infections have been unknowingly impairing maximum productivity on pig farms. Lack of availability of enough these highly efficacious PCV2 vaccine to meet the market demand now seems to be a major concern of pig farmers around the world.

The PCVD STREP and SSA will be completed in 2009 and although we now appear to be in a position of being able to control PCVDs by vaccination and/or nutrition and hopefully in the near future pig genetics, we will continue to expand our training and information networks, our research into the molecular interactions of PCV2 and other viruses with the pig immune system and the study of emerging viral infections of pigs. This EC-funded work will continue to train, expand and consolidate a network of enthusiastic young scientists across EU member states working in collaboration on important endemic, exotic and emerging pig diseases.

Further Reading

- Visit the PMWS and PCVD technical zone by clicking here.

5m Editor