The words “inclusion body disease” strike fear in the hearts of snake owners. The highly contagious ailment is well known at zoos and by exotic pet owners for the brain damage, behavioral changes, and wasting that it produces. For more than 30 years, the cause of this fatal disease was a mystery. HHMI investigator Joe DeRisi and his postdoctoral fellow, Mark Stenglein, recently uncovered a virus that may cause the disease and found an unexpected connection to fatal hemorrhagic fever in humans.
The telltale sign of inclusion body disease is the appearance of protein clumps inside a snake’s cells. The origin of those clusters was thought to be an unidentified virus. To test that hypothesis, DeRisi and his team at the University of California, San Francisco, sequenced the RNA from five diseased snakes. By comparing the RNA with RNA from healthy snakes, DeRisi was able to deduce which bits were foreign. His group assembled those pieces, revealing a novel viral genome. Stenglein showed that the virus produced the protein clumps characteristic of the disease.
|Meet the snakes and scientists that made this discovery possible.|
Surprisingly, DeRisi noticed that several of the snake virus genes were similar to ones found in arenaviruses and filoviruses (Ebola), which had been thought to occur only in mammals. Although genetically distinct, these two viruses can cause hemorrhagic fever in humans, and the newly identified snake virus hints that they share a common ancestor. Prior to their discovery, arenaviruses were only known in mammals. The existence of a reptile arenavirus suggests that this viral family is much larger and more extensive than was previously suspected.
The research, published August 14, 2012, in the open-access journal mBio, paves the way for developing diagnostics and treatments, which may help eradicate the fatal disease from snake collections worldwide.