‘New Ebola treatments may be obsolete before they’re available’
• Virus kill third of chimps, gorillas since 1990s
NEW treatments for Ebola could be obsolete before they are available for use by patients, because of genetic mutations in the disease, scientists have warned.
Experimental drugs that are in development are designed to bind to and target pieces of the virus’ genetic sequence – or proteins produced from that sequence.
But if the sequence changes, as a result of a ‘genetic drift’ – the natural evolution of the virus over time – the drugs may not work as effectively.
Meanwhile, there is a side to the Ebola crisis that, perhaps understandably, has received little media attention: the threat it poses to our nearest cousins, the great apes of Africa.
At this moment in time Ebola is the single greatest threat to the survival of gorillas and chimpanzees.
The virus is as deadly for great apes as it is for humans – with mortality rates at approximately 95 per cent for gorillas and 77 per cent for chimpanzees.
A new study has identified changes in the current strain of the disease, causing the outbreak in West Africa that could interfere with experimental drugs.
Gustavo Palacios, director of the Center for Genome Sciences at the US Army Medical Research Institute of Infectious Diseases, said: ‘We wanted to highlight an area where genomic drift, the natural process of evolution on this RNA virus genome, could affect the development of therapeutic countermeasures.
‘Our work highlights the genetic changes that could affect these sequence-based drugs that were originally designed in the early 2000’s based on virus strains from outbreaks in 1976 and 1995.’
The study tracked the genetic mutations that have occurred in the Ebola virus during the last four decades.
It was published in the American Society for Microbiology’s journal mBio.
It compared the entire genomic sequence of the current outbreak strain, called EBOV/Mak, with two other Ebola virus variants.
One was from an outbreak in Yambuku, Zaire in 1976 called EBOV/Yam-May, and one from an outbreak in Kikwit, Zaire in 1995 called EBOV/Kik-9510621.
It found changes, called single nucleotide polymorphisms, or SNPs, in more than 600 spots – or about three per cent of the genome.
Researchers then narrowed their search to only those mutations that changed the genetic sequences targeted by the various drugs.
Current estimates suggest a third of the world’s gorillas and chimpanzees have died from Ebola since the 1990s.
As with humans, these deaths tend to come in epidemics.
In 1995, an outbreak is reported to have killed more than 90 per cent of the gorillas in Minkébé Park in northern Gabon.
In 2002-2003, a single outbreak of ZEBOV – the Zaire strain of Ebola – in the Democratic Republic of Congo, killed an estimated 5,000 Western gorillas.
It’s hard to accurately count such elusive creatures but the WWF estimates there are up to 100,000 left in the wild – so a single Ebola outbreak wiped out a considerable chunk of the world’s gorilla population.
There are of course additional factors behind the declining numbers of Africa’s great apes: illegal trading in wildlife and bushmeat, war, deforestation and other infectious diseases.
The world’s remaining wild apes are increasingly being forced into isolated pockets of forest, which impedes their ability to forage, breed and to hide from hunters.