Scientists at Moredun Research Institute in Edinburgh have made a significant step forward in their research into an infectious lung cancer of sheep.

Ovine Pulmonary Adenocarcinoma (OPA) is a serious threat to the health and welfare of UK sheep. The disease is caused by infection with Jaagsiekte sheep retrovirus (JSRV). The virus is inhaled and infects cells in the lung, which then grow into tumours. These tumours produce more virus which infects more animals. Eventually the size of the lung tumours leads to the death of infected animals. In general, affected flocks may lose 1-5% of animals each year, but losses of up to 20% have been reported in some cases.

Moredun has been leading the research into this devastating disease for many years but has never been able to fully understand how the disease develops - especially in the early stages. However, in a paper published in the April edition of the Journal of Virology, Dr Henny Martineau and her colleagues from Moredun have described how they have been the first to identify specific cells in the lungs of young lambs that are targeted by the virus shortly after exposure to infection.

Henny Martineau commented, "The aim of this research was to study early stages of this disease and identify which cells in the lung are the first to become infected and then start to produce virus. This study has identified early viral expression in more than one cell type in the lungs of infected animals. These results will really help us to better understand how the disease develops."

In addition to its agricultural importance, OPA is also considered to be a good animal model for some kinds of human lung cancer. Lung cancer is the most common cancer in the world and over 40,000 new cases are diagnosed each year in the UK alone.

Dr Martineau added, "This work can also be used as a model for lung cancer in humans where it is difficult to detect early tumour growth before clinical signs are seen. Although there is no link between JSRV infection in sheep and lung cancer in humans, we hope that identifying the first cells to become cancerous in JSRV infections, may help to provide a means of detecting and possibly even treating lung cancer at earlier stages of development in humans in the future."

Nexxus Scotland

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