Medycyna Wet. 66 (6), 370-373, 2010
| Truszczyński M., Pejsak Z. |
| Immunosuppression as the cause of swine diseases of multifactorial etiology |
| After presenting the definition of immunosuppression the paper concentrates on the immunosuppressive properties of porcine circovirus type 2 (PCV2). Its role in the etiology of the post-weaning multisystemic wasting syndrome (PMWS) and the other porcine circovirus diseases (PCVD) is characterized, indicating that following the immunosuppressive action of PCV2 facultatively pathogenic microorganisms join the etiology of the disease syndrome which becomes multifactorial. The lymphocytopenia resulting from PCV2 infection is particularly manifest among the B lymphocytes, followed by the T lymphocytes. In vivo analyses have shown that PCV2 is most frequently associated with monocytes, macrophages and dendritic cells (DC). PCV2 infection of macrophages and DCs is the key factor determining the consequences for immune defense competence. The differences between conventional DCs (cDCs) and plasmacytoid DCs (pDCs) are mentioned. The term cDCs defines cells with antigen presenting functions and the term pDCs represents the interferon, type 1 producing cells. Examples of immunosuppressive action of other pathogens have been presented. Classical swine fever virus inhibits the interferon production in the infected DCs. In addition it causes leucopenia. These changes enablr opportunistic Pasteurella multocida and Streptococcus sp. strains to cause septicemia in the infected pigs. Immunosuppressive action of pseudorabies virus is mentioned resulting in secondary infection by other species of viruses or bacteria. Moreover, as presented in the paper, porcine reproductive and respiratory syndrome virus demonstrates immunosuppressive properties. |
| Keywords: immunosuppression, swine, PCV2 |