Skip to comments.A 3-Year Search Uncovers Novel Hemorrhagic Fever Virus
Posted on 09/29/2012 1:13:58 AM PDT by neverdem
A newly discovered virus from the family that causes rabies may be responsible for three linked cases of hemorrhagic fever in the Democratic Republic of the Congo more than 3 years ago.
Ebola virus, Marburg virus, Lassa fever, Rift Valley fever, yellow fever, and dengue are well known viruses from four different viral families that can cause hemorrhagic fever. But an international team of researchers report in PLoS Pathogens today that the rhabdovirus family, which typically causes brain swelling or flulike disease, can join the club of hemorrhagic fever agents, which are among the most virulent pathogens known to humans.
Using sophisticated RNA sequencing technology, the researchers discovered evidence that links a rhabdovirus to acute hemorrhagic fever in three people from the village of Mangala between 25 May and 14 June 2009. The first two people afflicted with the frightening disease died. But a third, a male nurse who treated both patients at a health center, survived.
The researchers did not actually isolate a rhabdovirus, but instead plucked out RNA sequences from the surviving man's blood sample and reconstructed what they contend is the genome of the pathogen that caused the disease. "It looks fairly solid," says Thomas Ksiazek, an epidemiologist and virologist who specializes in hemorrhagic disease at the University of Texas Medical Branch in Galveston. "Clearly, they have identified a virus in one of the three patients they describe. But trying to make more out of this is speculative. Is the disease due to the agent? You can speculate all you want, but until you have a virus in hand it's hard to answer that."
The PLoS Pathogens paper has 22 authors, a reflection of the long and winding journey from Mangala to the discovery of what they called the Bas-Congo virus, a reference to name of the Congolese province that includes Mangala village. First, the nurse's sample went to the Institut National de Recherche Biomédicale in Kinshasa, the capital of the Congo. When researchers there couldn't find any evidence of a pathogen, they sent the sample to Eric Leroy, a renowned authority on hemorrhagic fever at the Centre International de Recherches Médicales de Franceville (CIRMF) in Gabon. Leroy expanded the analysis and could not find any virus known to cause hemorrhagic fever in Africa. Global Viral Forecasting Inc., a for-profit company now called Metabiota and started by Nathan Wolfe of Stanford University, obtained a sample from CIRMF and gave it to Eric Delwart at Blood Systems Research Institute in San Francisco, California.
Delwart's group randomly amplified genetic material with the polymerase chain reaction, sequenced the products, and then checked what they created against databases of known genomes. "We got one very intriguing read," Delwart says. "It was clearly a rhabdovirus." But his team couldn't amplify any more meaningful sequence, so they passed the sample on to Charles Chiu, head of a viral discovery center at the University of California, San Francisco. Chiu sequenced 140 million fragments of genetic material and then merged related fragments to assemble the genome of the Bas-Congo virus.
Virologist Joseph Fair, who works with Metabiota, says the researchers could not isolate the actual virus because it took so long for the nurse's sample to arrive at a lab that could probe for agents. "We do the best we can with what we have here," Fair says, speaking by phone from Isiro, Congo, where he's working on a new Ebola outbreak. "We're trying to build capacity to build cold chains in cases like this."
Fair points to several lines of evidence that the Bas-Congo virus is real. He notes that the research teams exhaustively searched for other pathogens. "We found nothing except this rhabdovirus," he emphasizes. Based on genomic copies of Bas-Congo virus, the nurse also had high levels of the bug. The researchers then made a lab tool known as a pseudovirus, which contained the surface protein from Bas-Congo inside of a vesicular stomatitis virus, to run a confirmatory antibody test. Specifically, they showed that antibodies taken from the nurse in January 2012, as well as from an asymptomatic nurse who cared for him, prevented the pseudovirus from infecting cells in a culture dish. Fair and his co-authors also note that another hemorrhagic fever virus, Lujo, was first found in 2009 using similar genetic techniques to those they relied on.
But Fair acknowledges the importance of isolating the virus itself. "Since we weren't able to get an isolate, that limits what we can know about how it kills people and the effect it has on the immune system," Fair says. "Along with our Congolese colleagues, our next step will be to mount an expedition to find this virus."
Ping... (Thanks, neverdem!)
Thanks for posting this. Articles such as this are the reason I come to FR for my news.
Have you read anything on the protozoan parasite Babesia divergens, commonly known as “redwater fever” making its way into the USA? It’s primarily a bovine problem, but is finding its way into the USA blood supply.
Symptoms are commonly mistaken for malaria.
So the World health organization is excited at the prospect of all these pandemics for future use.
I don’t really care about a rare virus from the Congo that kills so quickly that it self limits and doesn’t much spread. I do care about the whitewash going on with the Yosemite Hauntavirus, that also causes hemorrhagic fever, bacause that’s right here.
Andromeda Strain, baby!
Hantavirus is pretty well associated only with rodent waste, so is not a serious threat outside of areas with a lot of rodents. Probably the worst outbreak was during the Korean War.
My guess is that due to weather conditions, there had been a population explosion of mice in the area.
The trouble with hemorrhagic fevers is that they are often both viral and indeterminate as to which virus is responsible. While rodent vectors are suspect, it could also be a pulmonary form which can spread very rapidly.
Babesia divergens didn't show up in Google News nor Yahoo News. But it makes me wonder about tickborne illness and claims of chronic Lyme disease. Have all other tickborne pathogens been ruled out? Or do more sophisticated genomic methods like this hemorrhagic fever story need to be employed?