The Clinical Infection with Pigeon Circovirus (PiCV) Leads to Lymphocyte B Apoptosis But Has No Effect on Lymphocyte T Subpopulation
Tomasz Stenzel, Daria Dziewulska, Bartłomiej Tykałowski, A. Koncicki
Abstract
The pathology of pigeon circovirus (PiCV) is still unknown, but it is regarded as an immunosuppressant. This study aimed to find a correlation between PiCV natural infection and immunosuppression. The study was conducted with 56 pigeons divided into the following groups: PiCV-positive but showing (group S) or not (group I) non-specific clinical symptoms and asymptomatic pigeons negative for PiCV (group H). The percentage and apoptosis of T CD3+ and B IgM+ splenocytes; the expression of CD4, CD8, and IFN-γ genes in splenic mononuclear cells; the number of PiCV viral loads in the bursa of Fabricius; and the level of anti-PiCV antibodies were analyzed. The results showed that the percentage of B IgM+ cells was almost two-fold lower in group S than in group H, and that ca. 20% of the lymphocytes were apoptotic. No increased apoptosis was detected in TCD3+ subpopulation. The PiCV viral loads were approximately one thousand and ten thousand times higher in group S than in groups I and H, respectively. Our results indicate a possible correlation between the number of PiCV viral loads and severity of PiCV infection and confirm that PiCV infection leads to the suppression of humoral immunity by inducing B lymphocyte apoptosis.