Haematoxylin and eosin stained sections from infected and control rabbit small intestine. Histological appearance of ileum in rabbits challenged by the intra-venous route with (a) bovine viral diarrhoea virus (BVDV) or (b) tissue culture medium (negative control). Intestinal lumen to the right and serosal surface to the left in both photomicrographs. a) note multiple areas of severe lymphoid cell depletion in the Peyer’s patches that had coalesced (black arrows) and were infiltrated by macrophages. Mild lymphoid cell depletion was present in the sub-epithelial domes (red arrows) also. b) note well-populated lymphoid tissue (black arrows) and the sub-epithelial domes (red arrows).