Blue ear disease (PRRS)
PRRS (porcine reproductive and respiratory syndrome) is a viral disease caused by the PRRS virus (PRRSV).
Porcine reproductive and respiratory syndrome is characterised by abortion, premature birth and high piglet mortality in sows, as well as pneumonia and mortality in weaned piglets and meat pigs. A typical, but less frequent, symptom is the occurrence of blue ears. For this reason, the disease is also known as blue ear disease.
Origin and transmission of PRRS
The disease originated suddenly at the end of the 1980s, virtually simultaneously in the United States and Europe, spreading around the world since then. It was associated with huge economic damage to the pig sector. In 2006 and 2007, South East Asia showed occurrences of infections with a variant of PRRSV, leading to extremely serious problems in pigs, resulting in with very high mortality rates. This variant contains a new genetic mutation that had arisen shortly before.
Since the inception of this disease, researchers at Wageningen Bioveterinary Research (WBVR) have played a significant role in discovering the virus, describing the disease and the development of vaccines.
PRRS vaccines came onto the market shortly after the virus was discovered. However, none of the current vaccines is able to ensure that animals do not become infected, that unborn piglets do not become infected in the womb and that virus excretion by infected animals is halted completely.
The reasons for this are varied and complex. One reason is that the genetic composition of the virus is extremely variable, with the result that the virus circulating in the field is able to evade the immunity generated by the vaccine. In this way, several types of PRRSV have arisen, such as the European and the American virus type, with several variants in between. New variant strains are increasingly being described. The new strains increase the risk that they can no longer be combated with the current vaccines.
Another important reason for the inadequate effectiveness of the PRRS vaccines - and this is what the WBVR research focusses on in particular - is the capacity of the virus to evade the immune system. The virus slows the capacity of the immune system to recognise it, to process it and to create a proper response. Our researchers are focussing on investigating these virus strategies with a view to developing a new generation of more effective vaccines.
Infection on pig farms
PRRS Clinical symptoms
The clinical symptoms are often not immediately indicative of PRRS. Laboratory diagnosis is needed in addition to the clinical symptoms, with the presence of the virus being shown by a PCR test or antibodies to the virus by an ELISA test. These tests are available at Wageningen Bioveterinary Research.
Effect of pooling family oral fluids on the probability of PRRSV RNA detection by RT-rtPCRPreventive Veterinary Medicine 206 (2022). - ISSN 0167-5877
Animal-Based Factors Prior to Infection Predict Histological Disease Outcome in Porcine Reproductive and Respiratory Syndrome Virus- and Actinobacillus pleuropneumoniae-Infected PigsFrontiers in Veterinary Science 8 (2021). - ISSN 2297-1769
Early immune responses in skin and lymph node after skin delivery of Toll-like receptor agonists in neonatal and adult pigsVaccine 39 (2021)13. - ISSN 0264-410X - p. 1857 - 1869.
Intestinal Viral Loads and Inactivation Kinetics of Livestock Viruses Relevant for Natural Casing Production: a Systematic Review and Meta-AnalysisPathogens 10 (2021)173. - ISSN 2076-0817
Immune responses induced by inactivated Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) vaccine in neonate pigs using different adjuvantsVeterinary Immunology and Immunopathology 232 (2021). - ISSN 0165-2427
Immune responses in neonatal and adult pigs following Toll-like receptor agonist adjuvanted vaccinationWageningen University. Promotor(en): H.F.J. Savelkoul, co-promotor(en): J.M.J. Rebel; N. Stockhofe-Zurwieden. - Wageningen : Wageningen University - ISBN 9789463953672 - p.
Toll-like receptor agonists as adjuvants for inactivated porcine reproductive and respiratory syndrome virus (PRRSV) vaccineVeterinary Immunology and Immunopathology 212 (2019). - ISSN 0165-2427 - p. 27 - 37.
Inactivated porcine reproductive and respiratory syndrome virus adjuvanted with single Toll like receptor 2, 7 and 9 agonists induces low antibody responses and limited protection
Genetic Characterization of Porcine Circovirus Type 2 (PCV2) in Pigs of BhutanTransboundary and Emerging Diseases 64 (2017)2. - ISSN 1865-1674 - p. 442 - 448.
Enriched Housing Reduces Disease Susceptibility to Co-Infection with Porcine Reproductive and Respiratory Virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae) in Young PigsPLoS ONE 11 (2016)9. - ISSN 1932-6203