Three new vaccines are being developed to tackle the rare species of Ebola that has already killed nearly 250 people.
The International Aids Vaccine Initiative (IAVI), which is working on one vaccine, said the outbreak was threatening to be the worst ever.
The University of Oxford and the pharma company Moderna are also researching vaccines against the Bundibugyo species.
The Coalition for Epidemic Preparedness Innovations, which is providing funding to each group, said “every day counts”.
There are now more than 1,000 suspected cases in the DR Congo with nine confirmed cases in neighbouring Uganda.
There is growing concern this outbreak – which was detected only after it had spread in a conflict zone with limited healthcare resources – could reach the size of the largest ever Ebola outbreak in West Africa in 2014-16. Then, nearly 29,000 people were infected and more than 11,000 died.
Dr Mark Feinberg, head of IAVI, said: “I think this is clearly threatening to be as severe an outbreak as that, if not even worse, and development of a vaccine, and other countermeasures, is clearly a priority.”
It echoes concerns from the medical charity Médecins Sans Frontières (MSF) which said the situation was “deeply alarming” and never before had “so many cases” been recorded so soon.
Vaccines must be developed for each individual species of Ebola – there are six, but only three are known to cause outbreaks.
There is a vaccine for the most common Zaire species, but this outbreak is being caused by another species, called Bundibugyo. It has only been seen twice before and there is no approved vaccine.
