Interaction of porcine reproductive and respiratory syndrome virus (PRRSV) with innate immunity
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Research partners:
Veterinary Laboratories Agency (VLA)
Sponsors: BPEX
Duration: 2009 – 2012
This project aims to investigate the influence of different strains of virus on their ability to cause disease and what role the immune response of the host to both the virus itself and secondary infections, plays in the outcome of disease. Using a number of different virus strains from Britain and worldwide, including a highly-pathogenic strain from Asia, the manner in which the virus interacts with the host and how this may vary will be examined.
During the first year of the project the first animal study was completed in collaboration with the Central Veterinary Institute in the Netherlands. Piglets were infected with one of three European strains of PRRS virus, the European reference strain Lelystad virus (LV), a recent field isolate from Belgium (07V063) and a more pathogenic strain from Belarus (Lena), and were later given an Aujeszky’s disease vaccine to explore immune modulation by the PRRS virus. Clinical scores and body temperatures were taken daily.
The initial results indicate that the Lena strain is more pathogenic than other European strains, concurring with findings performed by others where the Lena strain was found to lead to a 40% mortality rate. Animals challenged with the Lena strain displayed drops in populations of lymphocytes (white blood cells), cells which play a large role in defending the body against infection, during the first 10 days of challenge. However, this did not reflect a difference in antibody production, which was consistent between all three infected groups. Although the Lena-infected pigs displayed a fall in numbers of lymphocytes, the animals still cleared infectious virus from the blood by the end of the trial. It is possible that the virus affects the development of lymphocytes, explaining why the specific immune response begins very late on during PRRS.
Further analysis of the samples obtained during this study is required to gain a better understanding of what exactly is causing the fall in cell numbers. It is hoped that this work will improve our understanding of the interactions between the PRRS virus and the host (pig) immune system, informing the development of new, more effective, vaccines against PRRS.
Page last updated
04-Jan-2012