New ebola species threatens Africa

Following an outbreak of haemorrhagic fever in Uganda, scientists have isolated a new species of ebolavirus, genetically distinct from all other known species.

The ebolavirus has been responsible for sickness and death in Africa for 30 years, and all species have been thought to have a common ancestry. Outbreaks in humans are sporadic, although accompanied by high mortality rates. In November 2007, cases of haemorrhagic fever were reported in the Bundibugyo District, Western Uganda, and 29 blood samples were sent for immediate testing. Using a broad spectrum ebolavirus antigen capture assay, known to cross-react with different species, eight samples tested positive.

These same samples then tested negative when a highly sensitive real-time RT-PCR assay was used to identify the virus from the four known species of ebolavirus. Subsequent work was then carried out to sequence the genome of the new found virus. A specific real-time RT-PCR assay was then established to detect the draft sequence of viral DNA. In total, the outbreak caused 149 suspected cases and 37 deaths.

Work continued to sequence the genomes of the existing ebolaviruses, and it was found that the Uganda species differed by 30% of the genome to the pre-existing species, confirming that the Uganda outbreak of haemorrhagic fever was caused by a distinct species. Jonathan Towner, lead author in the USA of this collaborative project said “current efforts to design effective diagnostics, antivirals and vaccines will need to take into account the distinct nature of this important new member of the filovirus family”.

The project published evidence in the Public Library of Science.

By Georgina Lavender