New tests find deadly new virus that killed three

WASHINGTON (Reuters) - A previously unknown virus killed three women who got organ transplants from an Australian donor, and researchers say the technique they used to identify it could lead them to many more new infectious agents.

The as-yet-unnamed virus appears to be related to a bug called lymphocytic choriomeningitis virus, which usually causes only a minor flu-like illness.

But this one killed the three transplant patients by causing encephalitis, a swelling of the brain, the team reported on Wednesday in the New England Journal of Medicine.

The researchers used a relatively new method to find the virus, called high-throughput sequencing. They used powerful machines to get the full genetic sequences from the organs and from the patients, and filtered out everything but the sequences from the virus.

When the three women, ages 63, 64 and 44, all died in the Australian hospital after receiving a liver and two kidneys from the same man, doctors knew something was wrong. But a team at the Victoria Infectious Diseases Reference Laboratory could not find a cause.

"That donor died of a stroke and was not thought to have had an infectious disease at all," said Dr. Ian Lipkin of Columbia University in New York, who led the study.

Traditional methods such as trying to grow a virus or bacteria from samples, and even standard DNA sequencing, failed to turn up anything.

"As a result, the samples were sent to us," Lipkin said in a telephone interview.

HEAVYWEIGHT GENE MACHINE

His team used a new machine -- a high-throughput sequencer made by 454 Life Sciences, a part of Roche Applied Science and Roche AG.

These machines are usually used to mass-sequence entire genomes of large organisms, such as humans. It had never been used on a hunt like this one.

"After 100,000 different sequence analyses we found 14 (suspicious viral genetic sequences)," Lipkin said. "So it was a needle-in-a-haystack problem."

The RNA resembled the RNA from a type of virus known as an arenavirus, specifically lymphocytic choriomeningitis virus or LCMV, known to cause transplant-related disease and birth defects in addition to mild flu-like illness in healthy people.

The 57-year-old organ donor had recently visited the former Yugoslavia before dying of a cerebral hemorrhage in Australia, and Lipkin's team said the virus looked like it was of "Old World" origin.

"The virus is new and was not detected in 100 organ recipients who were not linked to this cluster," they wrote.

Lipkin said the method may be useful for diagnosing mysterious new ailments.

"We have so many diseases where there is no agent implicated," he said. "Over half of pneumonia and over half of encephalitis and over half of diarrheal disease are never diagnosed," he added.

"We need to be able to survey for old and new agents."

Christopher McLeod, president of 454 Life Sciences, said the machine might help identify emerging new infections, like the severe acute respiratory syndrome, or SARS, virus that appeared suddenly in China in 2002 and killed nearly 800 people globally before it was contained two years later.

"Over 30,000 organ transplants are performed in the U.S. each year. Knowledge of the genetic sequence of this virus might enable improvements in screening that will enhance the safety of transplantation," McLeod said in a statement.

(Editing by Will Dunham and Xavier Briand)