Jaagsiekte sheep retrovirus Jaagsiekte sheep retrovirus Jaagsiekte sheep retrovirus (JSRV) is a betaretrovirus which is the causative agent of a contagious lung cancer in sheep, called ovine pulmonary adenocarcinoma. JSRV is the virus that is the cause of the contagious lung tumors in sheep called ovine pulmonary adenocarcinoma (OPA). The disease has also been called "jaagsiekte", after the Afrikaans words for "chase" ("jaag") and "sickness" ("siekte"), to describe the respiratory distress observed in an animal out of breath from being chased, indicating the breathing difficulty experienced by infected sheep. Transmission of virus is through aerosol spread between sheep. The exogenous infectious form of
Ovine rinderpest gene. Lineages I and II are found mainly in West Africa. Lineage III is generally found in East Africa. Lineage IV was long known as the Asian lineage, but has now spread to the African continent and become the most prevalent lineage of all. This virus appears to have evolved at the start of the 20th century in Nigeria. The extant genotypes subsequently appeared in West Africa (lineages I and II), East Africa and Arabia (lineage III), and Pakistan–India (lineage IV). The first description of the disease was published in 1942 and relates to an outbreak in Côte d’Ivoire, West