Pathomorphological changes of the thymus of pigs at different stages of development of clinically expressed circovirus infection type ІІ

PCV2-infection of pigs plays an important role in the infectious pathology of pigs, having a significant impact on the economy of pig farms in different countries. Pathomorphological changes in the body of pigs with PCV2-infection occur moderately and in stages, as a result of the simultaneous launch of a set of mechanisms to counter the causative agent of the disease, resulting in the formation of a whole spectrum of reactive and pathological processes. The main “target” for PCV-2 is the immune system, and the multiplication of PCV-2 in the cells of the immune system leads to their death and development of immunodeficiency state. Thymus is the central organ of lymphocytopoiesis and imunopoiesis, in it occurs differentiation of all cellular forms of mature T-lymphocytes in the pre-T-lymphocyte stage, which migrate from the bone marrow to the bloodstream. The growth and development of the thymus, as well as the bone organs, is in direct interaction with the growth and development of the spleen, lymph nodes and is reflected in the structure of the interstitial connective tissue and lymphoid parenchyma. Purpose: determination of pathomorphological changes in the thymus of pigs at different stages of the development of clinically expressed PCV2-infection. Methods. The work was carried out in pig farms of Ukraine, with intensive technology of pig rearing, at the department of normal and pathological anatomy of agricultural animals and the Scientific and Research Center for Biosafety and Environmental Control of the Agroindustrial Complex Resources of Dnipro State Agrarian and Economic University. For pathomorphological studies, animals were selected with clinical signs of active PCV2‑infection (in 1 ml of whole blood of which contained more than 107 copies of the PCV-2 virus equivalent gene) and also piglets with positive optical density of specific antibodies (Ig G and Ig M) in serum blood. Pathomorphological changes were characterized by gradual exhaustion of the lymphoid parenchyma with a sharp decrease in the area of the cortical substance of the particles. Against the background of the degradation of the lymphoid parenchyma of the organ, there is a tendency to increase the relative area of the interstitial connective tissue, as well as the absolute size and number of thymic bodies, has been established.