Ovine pulmonary carcinoma (OPC, sheep pulmonary adenomatosis, jaagsiekte) occurs naturally as a contagious bronchioloalveolar carcinona of sheep in the Americas, Europe, Africa and Asia. The disease is endemic and economically important in Peru and apparently more common than previously suspected in the U.S.A. The tumor is a result of transformation of type II alveolar epithelial cells or non-ciliated bronchiolar cells of the lung. Clinically affected sheep develop dyspnea, tachypnea and often a watery nasal discharge that originates from tumor secretions. The course is progressive and death usually occurs within a few weeks. To study the viral etiology and pathogenesis of OPC in the U.S.A., the disease was experimentally transmitted to neonatal or young lambs with a success rate of 69%. Ovine lentivirus (OvLV), present in the inocula, was concurrently transmitted and induced lymphoid interstitial pneumonia in most animals. While morphological, immunological and other studies implicate a type D or type B retrovirus as the etiologic agent of OPC, this virus has not yet been cultured and the role of ovine lentivirus in the disease remains unknown.
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The authors would like to acknowledge the advice and technical assistance of Dr. J.M. Sharp of the Moredun Institute, Edinburgh, U.K., Dr. John Dahl-berg of the National Cancer Institute, Bethesda, MD and Dr. Enrique Amegh-ino of the IVITA Institute, San Marcos University, Lima, Peru. The excellent technical assistance of Helena Russell is appreciated. Richard Medville and Charles Kerlee provided invaluable assistance in electron microscopy and photography, respectively. This work was conducted as part of the U.S. Agency for International Development Title XII Small Ruminants CRSP in collaboration with Instituto Nacional de Investigacion y Promacion Agropecuaria, Lima, Peru, under grant No. AID/DSAN/VII-G-0048.