Natural History
JSRV is the virus that is the etiologic agent responsible for contagious lung tumors in sheep called Ovine Pulmonary Adenocarcinoma (OPA) .The disease was 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 that infected sheep have . Transmission of virus is through aerosol spread between sheep.
Exogenous infectious form of JSRV has an endogenous counterpart which is present in the genomes of all sheep and goats. The sheep genome has around 27 copies of endogenous retroviruses (enJSRVs) that are closely related to JSRV. Endogenous JSRV has several roles in the evolution of the domestic sheep as they are able to block the JSRV replication cycle and play a critical role in sheep conceptus development and placental morphogenesis.
Although OPA resembles human lung cancer, human lung cancer is not known to be caused by betaretroviruses. Even though a possibility of viral etiology has been eliminated in bronchoalveolar cancer, understanding the molecular mechanisms leading to the transformation of lung epithelia by JSRV may be of interest in the context of therapeutic approaches in human lung cancers in general and bronchoalveolar adenocarcinoma (BAC) in particular.
Read more about this topic: Jaagsiekte Sheep Retrovirus
Famous quotes containing the words natural and/or history:
“And if anyone should think I am tracing this matter too curiously, I, who have considered it in various shapes, can only answer with Hamlet ... “Not a jot”; it being no more than the natural result of examining and considering the subject.”
—Sarah Fielding (1710–1768)
“Perhaps universal history is the history of the diverse intonation of some metaphors.”
—Jorge Luis Borges (1899–1986)