Transmission of a malignant catarrhal fever-like syndrome to sheep: preliminary experiments.

The transmission of a malignant catarrhal fever-like syndrome to sheep is reported. Fetal sheep between 40 and 66 days gestation were inoculated intravenously with viable cells either from a red deer with clinical malignant catarrhal fever or from rabbits with the disease. Of the 21 fetuses in the experiment only five were born live and of these four developed clinical signs similar to malignant catarrhal fever in other species and died or were killed 10, 16, 47 and 175 days after birth. The fifth lamb remained unaffected. Histology of the four affected lambs revealed a generalised lymphoproliferation, with T-dependent areas of lymphoid tissues being affected, and an overall paucity of immunoglobulin containing cells. In addition arteritis and interstitial infiltration of many organs by lymphoid cells was present. The infectious agent was not reisolated in rabbits from lambs or passed to red deer housed in the same pen and it is thus considered possible that gene expression of the putative virus was incomplete.