New Deadly Virus Identified

A previously unknown virus has killed three recent transplant recipients who had a common Australian donor. All three patients, women aged 63, 64 and 44, had developed encephalitis, a swelling of the brain.

The new virus is not yet named, but seems to be related to the lymphocytic choriomeningitis virus, which usually causes only a minor flu-like illness.

When all three patients died in the Australian hospital after receiving a liver and two kidneys from the same man, doctors knew immediately something was wrong. However the medical team at the Victoria Infectious Diseases Reference Laboratory could not identify 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, in an interview with Reuters.

Traditional methods, such as DNA sequencing or growing a virus from samples, failed to produce results.

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

To identify the virus, Lipkin’s team used a relatively new method called high-throughput sequencing using a powerful machine made by 454 Life Sciences, a part of Roche Applied Science and Roche AG. The machines then determined the full genetic sequences from the organs and from the patients, and everything but the virus sequence was filtered out.

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.

Researchers said the process used to identify the new virus could pave the way to finding many new infectious agents.

"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.

Researchers said the 57-year-old organ donor had recently visited the former Yugoslavia before dying of a cerebral hemorrhage in Australia. Lipkin’s team said the virus looked to be 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 added that the method used to identify the virus might be useful for diagnosing other 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 said.

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

454 Life Sciences president Christopher McLeod said the machine might help identify emerging new infections, like the severe acute respiratory syndrome, or SARS, virus that appeared abruptly 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.

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Photo Caption: Predominantly Membranous Distribution of Arenavirus Antigen. The distribution of the arenavirus antigen is shown in the liver (Panel A) and kidney (Panel B) of Recipient 1. Formalin-fixed, paraffin-embedded tissue sections were incubated with polyclonal rabbit antiserum against lymphocytic choriomeningitis virus followed by alkaline phosphatase”“conjugated secondary antibodies against rabbit IgG.

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On the Net:

The full report was published February 6th in the New England Journal of Medicine, and can be viewed here.