Scientists racing to develop potential vaccines and treatments against a deadly Ebola outbreak are having to do so without a viable sample of the virus, highlighting growing disputes over pathogen sharing and the difficulty of moving infectious materials across borders for research.

More than a month after the outbreak was identified in Democratic Republic of the Congo, researchers are still relying on virus samples collected during earlier epidemics. That makes it harder to determine whether experimental vaccines and treatments will work against the current virus and to validate laboratory tests designed to detect it.

“There’s nothing like having the authentic isolate,” said Thomas Geisbert, a professor of microbiology and immunology at the University of Texas Medical Branch in Galveston, who helped develop Ebola vaccines.

The work is especially urgent because no vaccine or treatment has been approved for the rare Bundibugyo strain spreading in eastern Congo. The delay appears to reflect concerns about sharing pathogen samples that could be used to develop commercial products, according to people familiar with the matter. They asked not to be identified because the issue is politically sensitive.

Congo’s health ministry and the National Institute for Biomedical Research didn’t respond to calls and text messages this week seeking comment. Government spokesman Patrick Muyaya said no official request had been received.

It remains unclear why virus isolates from the current outbreak haven’t been transferred outside Congo.

The issue reflects a broader debate over pathogen sharing that has intensified since the Covid-19 pandemic. Countries where outbreaks occur have increasingly sought greater control over biological materials, arguing they have often shared virus samples only to see vaccines and treatments developed elsewhere while their own populations received limited or delayed access. At the same time, scientists say transporting infectious pathogens across borders has come under heightened scrutiny, adding another layer of complexity.

Those tensions are reflected in talks at the World Health Organization, where member states remain deadlocked over a pathogen access and benefit-sharing system, the last major unresolved element of the Pandemic Agreement negotiated after the pandemic. The proposed framework aims to speed the sharing of pathogens while ensuring countries where outbreaks occur receive vaccines, medicines and other benefits developed from them. Formal talks resume in July.

Hunger and war

The outbreak has sickened more than 1,100 people in Congo and Uganda and killed almost 280. Health officials have struggled to trace contacts and contain transmission in a region beset by insecurity, displacement, hunger and gaps in disease surveillance. This week, one infection emerged in France in a doctor returning from doing humanitarian work in one of Congo’s hardest-hit areas.

“Despite so many cases, the global scientific community has not obtained a clinical sample to isolate the virus for the needed animal challenge studies,” said Jennifer Serwanga, head of immunology at the Uganda Virus Research Institute.

Blood samples are routinely collected from Ebola patients for diagnosis and genetic sequencing. Producing a research-quality virus isolate is a more technically demanding process that requires specialized high-containment laboratories, where scientists recover the virus from clinical specimens and grow it under controlled conditions.

Vaccine search

“It would be valuable to have that isolate so that we could look at it in animal models where we can really control the experimental conditions,” Geisbert said.

He and others stress that the missing virus sample isn’t preventing vaccine development. Genetic sequences from the current outbreak show the virus remains highly similar to strains responsible for Bundibugyo outbreaks in 2007 and 2012.

But having the outbreak virus would provide a level of confidence that genetic sequence analysis alone cannot, scientists said.

“For most of us, the idea is simply to get drugs or vaccine or diagnostics where they are needed,” said Robert Garry, a virologist at Tulane University. “That’s incredibly difficult to do and anything that makes the process harder is not helpful.”

—With assistance from Michael J. Kavanagh and Jessica Nix.

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