'Bas-Congo': Genetic sleuthing uncovers deadly new virus in Africa
This is an electron microscope image of a typical rhabdovirus. Credit: UCSF
An isolated outbreak of a deadly disease known as acute hemorrhagic fever, which killed two people and left one gravely ill in the Democratic Republic of Congo in the summer of 2009, was probably caused by a novel virus scientists have never seen before.
Described this week in the open-access journal PLoS Pathogens, the new microbe has been named Bas-Congo virus (BASV) after the province in the southwest corner of the Congo where the three people lived.
It was discovered by an international research consortium that included the University of California, San Francisco (UCSF) and University of California, Davis (UCD), Global Viral, the Centre International de Recherches Médicales de Franceville in Gabon, the Institut National de Recherche Biomédicale, Kinshasa in the Democratic Republic of the Congo, Metabiota and others.
"Known viruses, such as Ebola, HIV and influenza, represent just the tip of the microbial iceberg," said Joseph Fair, PhD, a co-author and vice president of Metabiota. "Identifying deadly unknown viruses, such as Bas-Congo virus, gives us a leg up in controlling future outbreaks."
"These are the only three cases known to have occurred, although there could be additional outbreaks from this virus in the future," said Charles Chiu, MD, PhD, an assistant professor of laboratory medicine at UCSF and director of the UCSF-Abbott Viral Diagnostics and Discovery Center, who spearheaded the UCSF effort to identify the virus. Chiu and his team continue to work on new diagnostics to detect the virus so that health officials in Congo and elsewhere can quickly identify it should it emerge again.
One odd characteristic of the Bas-Congo virus, Chiu said, is that while a number of other viruses in Africa also cause deadly outbreaks of acute hemorrhagic fever—Ebola virus, Lassa virus and Crimean-Congo Hemorrhagic Fever virus to name a few —the new virus is unlike any of them.
Genetically it is more closely related to the types of viruses that cause rabies, which are known to infect people with a very different sort of disease—a neurological illness that is uniformly fatal if untreated but may take months to develop.
An antibody test developed in this study was applied to the one patient who survived and to others who had come into contact with him. It suggested that the disease may be spread from person to person but likely originated from some other source, such as an insect or rodent.
This is an image of collecting samples in the Jungles of Boma in 2009 after the outbreak. Courtesy: Metabiota Credit: MetabiotaThe identity of this animal "reservoir" and the precise mode of transmission for the virus remain unclear and are currently being investigated by Metabiota and the central African members of the consortium through the PREDICT Project of USAID's Emerging Pandemic Threats Program.
How the New Virus Emerged
In the summer of 2009, a 15-year old boy in a small rural community called Mangala village suddenly fell ill and developed a bleeding nose, bleeding gums and bloody vomit. He rapidly worsened, dying within three days of the first signs of illness.
A week later, a 13-year old girl who attended the same school and lived in the same neighborhood as the boy came down with a similar, serious illness. She declined just as rapidly and also died within three days. One week after that, the male nurse who cared for this girl began showing the same symptoms, and he was transferred to a hospital in Boma, a nearby port city that sits along the Congo River upstream from Africa's Atlantic coast.
Members of the consortium, who had initiated a project to diagnose unusual cases of severe hemorrhagic fever, obtained blood samples collected from the nurse by the Congolese doctors and sent them to the laboratory of Eric Leroy, PhD, doctor of veterinary medicine at the Centre International de Recherches Médicales de Franceville in Gabon. There the samples were tested for traces of any known virus, but nothing was found. The Metabiota scientists then solicited the expertise of Chiu at UCSF and Eric Delwart at the Blood Systems Research Institute (BSRI) in San Francisco to aid in the diagnosis.
The researchers ultimately identified a completely new virus as the cause of the mysterious illness through a powerful strategy for identifying novel pathogens known as "deep sequencing," in which millions of DNA sequences are generated from a clinical sample and then pieced together using computer algorithms combined with human analysis.
Distinct Attributes of Bas-Congo
The Bas-Congo virus belongs to a family of viruses known as the rhabdoviruses, a large family of viruses that infect plants, insects and mammals, including humans. The most famous member of this family is the virus that causes rabies. But even among the rhabdoviruses, Bas-Congo is something of an outlier, being very genetically distinct from other members of the family.
What's most unusual about this virus, though, said Chiu, is what it does to people.
No other rhabdoviruses are known to cause the acute, rapid and deadly hemorrhagic fever seen in the three cases in the Congo. Rabies, for instance, can be a deadly disease if untreated, but the course of rabies in humans is nothing like the rapid and deadly onset seen with the Bas-Congo virus. There is some precedent, however, for hemorrhagic disease from rhabdoviruses in the animal kingdom: fish rhabdoviruses are known to cause hemorrhagic septicemia—acute bleeding and death—in affected fish.
The third patient had enormous amounts of BASV in his bloodstream just two days after he fell ill—more than a million copies in every milliliter of blood.
The BASV sequence was also used to design an antibody test for the virus, an effort led by Graham Simmons at the BSRI, another member of the consortium. Antibodies are blood immune proteins produced in response to an infection. The antibody test allowed the researchers to screen both the third patient with acute hemorrhagic fever and other people who had come into contact with the third patient, including the nurse who cared for him in the Boma hospital. High levels of BASV-specific antibodies were found in the third patient, establishing that he indeed had been infected with Bas-Congo virus. The same antibodies were also found in the second nurse, even though he never actually became sick.
"What this suggests is that the disease may be transmissible from person to person—though it's most likely to have originated from some other source," said Nathan Wolfe, PhD, founder and chairman of Global Viral, and a co-author on the paper. "The fact that it belongs to a family of viruses known to infect a wide variety of mammals, insects and other animals means that it may perpetually exist in insect or other 'host' species and was accidentally passed to humans through insect bites or some other means."
Journal reference: PLoS Pathogens
Provided by University of California, San Francisco
- UCSF confirms first adenovirus to jump between monkeys and humans Jul 14, 2011 | not rated yet | 0
- Ebola outbreak in DR Congo Aug 18, 2012 | not rated yet | 0
- Scientists reveal how deadly Marburg virus silences immune system Sep 13, 2012 | not rated yet | 0
- Scientists detect presence of marburg virus in african fruit bats Aug 22, 2007 | not rated yet | 0
- Uganda Ebola outbreak 'coming to an end': WHO Sep 03, 2012 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Classical and Quantum Mechanics via Lie algebras
Apr 15, 2011 I'd like to open a discussion thread for version 2 of the draft of my book ''Classical and Quantum Mechanics via Lie algebras'', available online at http://lanl.arxiv.org/abs/0810.1019 , and for the...
- More from Physics Forums - Independent Research
More news stories
Gourmands and foodies everywhere have long recognized ginger as a great way to add a little peppery zing to both sweet and savory dishes; now, a study from researchers at Columbia University shows purified components of the ...
Diseases, Conditions, Syndromes 16 minutes ago | not rated yet | 0
There are significant cost and risk factors associated with two procedures commonly used to diagnose or treat gastrointestinal problems, according to research presented at Digestive Disease Week (DDW).
Diseases, Conditions, Syndromes 12 hours ago | not rated yet | 0
Regular consumption of coffee is associated with a reduced risk of primary sclerosing cholangitis (PSC), an autoimmune liver disease, Mayo Clinic research shows. The findings were being presented at the Digestive Disease ...
Diseases, Conditions, Syndromes 12 hours ago | not rated yet | 0 |
A new case of the deadly coronavirus has been detected in Saudi Arabia where 15 people have already died after contracting it, the health ministry announced on Saturday on its Internet website.
Diseases, Conditions, Syndromes May 18, 2013 | not rated yet | 0
(HealthDay)—Few randomized clinical trials have been done to assess clinical prediction rules for patients with lower back pain, and the trials that have been done are of low quality and do not provide ...
Diseases, Conditions, Syndromes May 17, 2013 | not rated yet | 0 |
Researchers at the University of Wisconsin have identified a potential new risk factor for obstructive sleep apnea: asthma. Using data from the National Institutes of Health (Heart, Lung, and Blood Institute)-funded Wisconsin ...
16 minutes ago | not rated yet | 0 |
A new study looking at sleep-disordered breathing (SDB) and markers for Alzheimer's disease (AD) risk in cerebrospinal fluid (CSF) and neuroimaging adds to the growing body of research linking the two.
26 minutes ago | not rated yet | 0 |
In their quest to learn more about the variability of cells between and within tissues, biomedical scientists have devised tools capable of simultaneously measuring dozens of characteristics of individual ...
1 hour ago | not rated yet | 0 |
Scientists at Johns Hopkins have turned their view of osteoarthritis (OA) inside out. Literally. Instead of seeing the painful degenerative disease as a problem primarily of the cartilage that cushions joints, ...
1 hour ago | 5 / 5 (1) | 0 |
The hunt for an HIV vaccine has gobbled up $8 billion in the past decade, and the failure of the most recent efficacy trial has delivered yet another setback to 26 years of efforts.
5 hours ago | not rated yet | 0
The devastating effect of Alzheimer's disease on bilingual people has been thrown into focus in Canada, where the sudden loss of a second language can leave sufferers feeling like strangers in their own country.
3 hours ago | not rated yet | 0