Animal Health and Welfare

Project: Early pathogenesis of porcine circovirus

Subprogramme: Pig Health

Project Objectives

Porcine circovirus type 2 (PCV2) is the causative agent of post weaning multisystemic wasting syndrome (PMWS), a disease which is spreading rapidly in Europe with devastating consequences for the pig industry. Studies on field cases of PCV2 -associated disease indicate a relationship between the virus and cells of the immune system. In particular, large concentrations of virus antigen in histiocytes and other monocyte-type cells appear to be a consistent feature. While some studies have described presence of virus antigen in some lymphocytes, this has not been a consistent feature in all cases. Most studies to date have concentrated on events in the later stages of the infectious process or on field cases of pigs showing clinical signs. Little or nothing is known of the early pathogenesis, yet this period of the disease is likely to be important in determining future outcomes. This project seeks to elucidate the first steps in the disease process, particularly the association of the virus with cells of the immune system, which appears to be the pivotal event in disease pathogenesis. An additional aim of this project is to exploit current knowledge of circovirus molecular biology to generate replication-impaired PCV2 mutants. The degree of attenuation exhibited by such viruses will be assessed with the aim of developing candidate live vaccines.