Several vaccines against Bundibugyo virus are being developed as scientists work to close a gap in Ebola protection.
ALSO READ: First human trial begins for Bundibugyo Ebola vaccine
The strain is behind the ongoing outbreak in the DR Congo, Uganda, which also reported an outbreak, declared it over in August, while France reported an imported case. Kenya confirmed its first imported case on October 6 after a traveller from the DR Congo later died.
There is no licensed vaccine specifically for Bundibugyo virus. Two vaccine candidates have entered Phase 1 trials, while others are still in development. Work is under way to prepare for vaccine production if the candidates prove effective.
Here are the main vaccine candidates in development:
ChAdOx1 BDBV
The University of Oxford’s candidate became the first Bundibugyo vaccine to enter human testing, with its first-in-human Phase 1a trial launched in July. The study in Oxford is assessing the vaccine’s safety and immune response in 50 healthy adults.
A Phase 1b study began in Uganda on October 6, with the first participants vaccinated in Masaka City. The trial is assessing the same vaccine in healthy Ugandan adults. ChAdOx1 BDBV uses the same vaccine technology as the Oxford-AstraZeneca Covid-19 vaccine.
The Serum Institute of India has already manufactured and stockpiled about 620,000 doses of the vaccine.
mRNA-1469
US biotechnology company Moderna began testing its candidate in humans for the first time in Canada in August. About 80 healthy adults are taking part at three sites, where researchers are assessing its safety, tolerability and immune response.
The vaccine uses messenger RNA technology. The Coalition for Epidemic Preparedness Innovations (CEPI) is providing up to US$50 million to support its development and manufacture of additional doses for later trials. If eventually licensed, Moderna has committed to making at least 500,000 doses available to low- and middle-income countries at access pricing.
rVSV-BDBV-GP
This one-dose candidate uses recombinant vesicular stomatitis virus (rVSV), the same broad platform used in the licensed Ervebo vaccine for Zaire Ebola.
The International AIDS Vaccine Initiative (IAVI) is advancing the candidate after reaching an agreement with the University of Texas Medical Branch. Preclinical studies have shown protection in non-human primates, but human trials have not yet begun.
Hilleman Laboratories, a Singapore-based joint venture between Merck & Co. (MSD) and Wellcome, is working with the Coalition for Epidemic Preparedness Innovations (CEPI) to develop and manufacture clinical trial doses using material from the IAVI programme. CEPI has committed up to US$8.5 million to the work. Hilleman is supporting the development and manufacture of the vaccine rather than developing a separate candidate.
MVA-CR19
Minapharm Group and its Berlin-based subsidiary, ProBioGen, are developing MVA-CR19 using a modified vaccinia Ankara (MVA) platform. The vaccine is designed to trigger antibodies and T-cells, which help the body recognise and fight the virus.
The Coalition for Epidemic Preparedness Innovations (CEPI) has committed up to US$16.5 million to take the candidate through preclinical development and into Phase 1 testing in Africa.
The programme also plans to manufacture the vaccine in Africa. Minapharm is expected to produce it at its facility in Egypt. Clinical testing is also being prepared in Rwanda, with the programme expecting to begin Phase 1 testing in December. The study is expected to take place at the University of Global Health Equity (UGHE) and King Faisal Hospital. The Rwanda Biomedical Centre (RBC) will sponsor the clinical team, while the African Medicines Agency (AMA) will oversee the regulatory process.
PHV04
Public Health Vaccines (PHV) has PHV04 in its pipeline as another Bundibugyo vaccine candidate using the rVSV platform.
The candidate remains at an earlier stage of development. PHV has also been advancing Bundibugyo and Sudan virus vaccine candidates under support linked to the US government agency Biomedical Advanced Research and Development Authority (BARDA).
GeoVax BDBV vaccine construct
GeoVax Labs has developed a Bundibugyo-specific vaccine construct using its proprietary MVA-based rapid-cloning technology. The construct is still at an early stage. Further characterisation and animal evaluation are required before it can move into clinical testing.
What happens before rollout?
The two candidates now in Phase 1 trials are being tested for safety and the immune response they produce. If the results are promising, larger trials will be needed to determine whether they can protect people against Bundibugyo virus before regulators can consider them for approval.
The World Health Organization (WHO) says Ervebo, the only licensed Ebola vaccine, is approved for the Zaire species. There is not enough evidence to confirm that it protects people against the Bundibugyo virus, so WHO recommends its use against the virus only under research protocols.