The Pathological Lesions And Apoptosis Induced By PCV-2 In Lymph Nodes Of Pigs

Some kinds of diseases are related with porcine circovirus type 2 (PCV-2) in porcine groups including PMWS, PDNS, CT, et al. Especially, PMWS is the most serious and has made great economic losses in the world. As reported previously, PCV -2 may induces the damnification of the immune system. Discerning how PCV-2 interact with the immune system is crucial for a better understanding of viral pathogenesis. The objective of these studies is to explore the effects of PCV-2 infection on immune system at the apoptosis and cytokines.In this report, nine 32-day-old conventional piglets free of PCV-2 antibody were used, distributed in three groups. Three pigs received PCV-2 alone (PCV-2 group). Three pigs were stimulated with KLH after inoculating PCV-2 (PCV-2 + KLH group ) . Three control pigs received nothing (control group). The lymph nodes, spleens, hearts, lungs, livers and kidneys of these pigs were collected after 32 days postinoculation. The characteristic histopathological lesion have been seen in superficial inguinal lymph nodes, spleens and lungs of the piglets of PCV-2 group and PCV-2 + KLH group: Lymphocyte depletion in cortex and paracortex of lymph node, lymphoid nodule atrophy, epithelioid macrophages infiltration, mtracytoplasmic inclusion bodies in epithelioid macrophages are present in lymph nodes. There is appearance of infiltration with epithelioid macrophages in periarteriolar lymphoid sheath of spleen. Alveolar septum, infiltration with macrophages, is thickened. Histopathological lesions of the piglets of PCV-2 + KLH group were more severe than that of PCV-2 group .Microscopic lesions showed that PCV-2 did a lot of damage to the lymph node. In this study we investigated the pathogenetic mechanism of induction lymphocyte depletion in pig's lymph nodes infected by PCV-2. The superficial inguinal lymph nodes of pigs in the 3 groups were collected at 32 days post-inoculation (DPI) PCV-2. PCV-2 in the lymph nodes was located with immunohistochemistry(IHC) and the apoptosis were observed by both TUNEL and flow cytometry(FCM). The results indicated that PCV-2 antigens were mainly found in the epithelioid macrophages of lymphoid nodule of pigs on PCV-2 group and PCV-2+KLH group. TUNEL-positive cells were mostly lymphocytes in lymphoid nodule of the above two groups The average apoptotic rates of lymph nodes were 3.34 % and 4.88 % in pigs of PCV-2 group and PCV-2+KLH group by flow cytometry respectively. The data...