Last week, genetic scientists announced the discovery of a new species: a deadly virus. Researchers at the University of California in San Francisco – an institution known for its work wth unknown viruses – used cutting-edge genetic sequencing techniques to identify the Bas-Congo Virus (BASV), named after the region of central Africa where the disease originated. The article describing their findings, A Novel Rhabdovirus Associated with Acute Hemorrhagic Fever in Central Africa, appears in the open source journal PLOS Pathogens.
The story begins in Mangala, a village in the Democratic Republic of Congo, a country in the center of the African continent. A fifteen-year-old boy became suddenly and violently ill with hemorrhagic fever, bleeding from his mucous membranes, and died within three days of his first symptoms. The following week, a thirteen-year-old girl developed the same symptoms and died just as quickly. Soon, a third patient fell ill, a male nurse who cared for the two teenagers. He survived, and samples from his blood enabled geneticists to study the virus.
The first phases of the research took place in Africa, carried out by local hospitals in the DRC, Doctors Without Borders, and the DRC’s National Institute for Biomedical Research. These organizations sent the samples to Dr. Eric Leroy,who directs CIRMF, a virology research center in the nearby country of Gabon. Leroy discovered that this virus was unlike any of the viruses known to cause hemorrhagic fever, and enlisted the help of scientists in California to see if a new species had really been uncovered.
The UCSF team used an innovative new process to sequence the Bas-Congo Virus’s genome, one more accurate and thorough than those used in the past. The technique, genetic deep sequencing, allows scientists to scan and record a large number of genetic sequences very fast. This makes it possible to obtain accurate information about viruses that are mutating rapidly, and to differentiate between viruses that appear similar.
At first, the researchers expected that the Bas-Congo Virus would be related to other viruses that cause hemorrhagic fever outbreaks in central Africa, such as Ebola and Marburg. What they found, however, was that BASV belongs to a completely different family of viruses called Rhabdoviruses. This was a surprise because no rhabdovirus has ever been identified as the cause of a hemorrhagic fever in humans, although they do sometimes cause other kinds of disease – the most famous rhabdovirus causes rabies. Charles Chiu, a co-author of the study, told NPR, “even within the rhabdovirus family, it’s very divergent.”
No one else in Mangala has fallen ill with Bas-Congo Virus since the initial outbreak, which makes it difficult to learn more about the disease. The researchers suspect that an insect host transmitted the virus to the human victims, but none has been identified yet, meaning that scientists still know very little about the life cycle and transmission pattern of BASV. In an article for National Geographic, one of the study’s co-authors, Nathan D. Wolfe, writes, “in our line of work the excitement of scientific discovery is often dampened by the reality of the suffering of individuals intimately impacted by viruses such as BASV.”
As only three people have ever fallen ill with BASV, studying the new virus will not immediately alleviate that suffering.Nonetheless, this research makes an important step toward diagnosing the estimated 20% of hemorrhagic fevers in Africa whose cause is never identified, and toward preventing future outbreaks.