Ultrastructural pathology of the bone marrow in pigs inoculated with a moderately virulent strain (DR'78) of African swine fever virus.

Interpretation of changes in bone marrow during infectious processes is quite complex. This paper reports bone marrow lesions observed in pigs inoculated with a moderately virulent ASF virus strain and studies their relationship to the pathogenesis of the disease. In this work, we have carried out the structural and ultrastructural study of the bone marrow of 14 Large White x Landrace pigs that were inoculated by the intramuscular route with 10(5) 50% hemodsorbing doses (HAD50) of the Dominican Republic'78 ASF virus strain. The inoculated pigs were killed at 3, 5, 7, 9, 11, 13, 15 and 17 days postinjection. Analysis of cells and structures belonging to the two main bone-marrow compartments, the hematopoietic cells and the hematopoietic micro-environment, showed that after inoculation with a moderately virulent strain, the most significant changes occurred in macrophages and megakaryocytes, consisting in virus replication in these cell populations and apoptosis of megakaryocytes, related with the sudden and transitory thrombocytopenia detected in the subacute ASF.