Experimental African swine fever: apoptosis of lymphocytes and virus replication in other cells

1 Departamento de Anatomía y Anatomía Patológica Comparadas, Facultad de Veterinaria, Universidad de Córdoba, Avda. de Medina Azahara 7, 14005 Córdoba, Spain 2 Centro de Biología Molecular (CSIC-UAM), Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain and 3 Institute for Animal Health, Pirbright Laboratory, Pirbright, Surrey, UK In order to determine the cause of cellular death of lymphocytes in pigs with acute African swine fever and the relationships between African swine fever virus (ASFV) and interstitial cells, ten pigs were inoculated with a highly virulent strain of ASFV (Malawi '83) and samples taken for ultrastructural study of hepatic and renal interstitial tissues. We demonstrated death by apoptosis of lymphocytes and virus replication in fibroblasts, smooth muscle cells and endothelial cells in the interstitial tissues of pigs inoculated with ASFV. From day 5 onwards, apoptotic lymphocytes and intense virus replication in hepatic interstitial macrophages and fibroblasts were observed. By day 7, apoptotic lymphocytes and virus replication in macrophages, interstitial capillary endothelial cells and fibroblasts in the kidney were observed. Virus replication was also seen in smooth muscle cells of hepatic and renal arterioles and venules. Our results suggest that mononuclear phagocyte system (MPS) cell activation, and the resulting release of cytokines, could induce apoptosis of lymphocytes and virus replication in non-MPS cells. * Author for correspondence. Fax +34 57 218666. e-mail cc0gralf@lucano.uco.es Received 31 January 1995; accepted 3 May 1995.