Apoptosis in the lymphatic organs of piglets inoculated with classical swine fever virus

The involvement of apoptosis in the lymphatic organs of piglets infected wi th classical swine fever (CSF) virus was investigated. Piglets were inocula ted with CSF virus and 3, 5, 7 and 10 days post inoculation (DPI), the thym us, spleen and lymph node were examined. In the thymus cortex, macrophages phagocytizing the nuclear remnants or apoptotic bodies increased after 3 DP I. Thymus atrophy due to the loss of the cortex increased markedly during t he observation period. Compact and shrunken nuclei indicating apoptosis wer e observed in the spleen and lymph node. DNA fragmentation was detected in the nuclei of lymphocytes in the thymus, spleen and lymph nodes, as well as at sites of focal necrosis. Using the terminal deoxynucleotidyl transferas e-mediated dUTP-biotin nick end labeling method, ultrastructural characteri stics of apoptosis, i.e. margination of condensed nuclear chromatin, were o bserved in the lymphatic organs from 2 DPI onward. These results suggest th at apoptosis is involved in the pathology of CSF (C) 2000 Elsevier Science B.V. All rights reserved.