U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Agricultural Research May/June 2013.


The discovery of a gene associated with a persistent viral infection that causes an incurable disease—ovine progressive pneumonia (OPP)—in sheep has led to the development of a genetic test that can be used to help reduce the impact of the disease.

A slow-acting, wasting disease, OPP affects millions of sheep worldwide and is one of the most costly diseases to producers in North America. Previous research revealed that 36 percent of sheep operations and 24 percent of sheep tested in the United States were infected with ovine progressive pneumonia virus (OPPV)—lentivirus strains that target the immune system and cause OPP.

Once infected, sheep are infected for life. Infected ewes are about 20 percent less productive, having fewer lambs and that also weigh less than lambs born to uninfected ewes. In addition to pneumonia, they show signs of wasting, lameness, and “hard bag” syndrome, in which udders become hard and contain barely any milk. Infected ewes are often culled—removed from the flock.

Scientists at the Agricultural Research Service Roman L. Hruska U.S. Meat Animal Research Center (USMARC) in Clay Center, Nebraska, along with their colleagues at the Animal Disease Research Unit in Pullman, Washington, and the U.S. Sheep Experiment Station near Dubois, Idaho, have found and verified that the gene— TMEM154— affects susceptibility to OPPV infection in sheep.