Scientists in Japan have begun a new clinical trial for a potential Ebola vaccine developed by researchers in the UW-Madison School of Veterinary Medicine.
The new vaccine is different from most experimental vaccines, which typically use a secondary virus to deliver part of the Ebola virus to the immune system. The new vaccine contains only the Ebola virus, though the gene that enables viral infections has been edited out.
Yoshihiro Kawaoka is a professor of pathobiological sciences who led the development of the vaccine alongside research associate Prof. Peter Halfmann. He says the vaccine leads to more protective antibodies being created in treated patients.
“Our vaccine contains everything except one small protein … and it’s an inactivated virus, so it’s safer,” Kawaoka said.
In the first phase of the clinical trial, 15 young men in good health will receive two doses of the experimental vaccine. Women aren’t being included in this phase to avoid any subjects who could be pregnant, as the Ebola virus poses more of a threat to pregnant women. Importantly, no subjects will be exposed to the virus in the first phase of the trial.
If that first group tolerates the vaccine, another group of 20 subjects will get a higher dose.
“In phase one, the main goal is safety,” Kawaoka said.
Researchers will determine if participants’ immune systems begin developing antibodies and “immune memory” for Ebola, which would suggest they’re gaining resistance to the virus.
According to a release from UW-Madison, this new vaccine contains more virus proteins than others and “improves the chances the immune system develops a robust capacity to fight Ebola virus if a person is exposed.”
The genetically altered form of the virus — the basis for the new vaccine — can only be grown in a particular cellular system that contains the missing protein. Its safety has previously been shown in mice, guinea pigs and non-human primates.
The new vaccine builds on more than a decade of work spearheaded by Halfmann, who created a method for rendering the Ebola virus incapable of reproduction. According to him, the method for changing the Ebola virus was created as a simple research tool.
“I never really thought we would have the backing behind us to actually go for a vaccine,” he said. “It’s exciting to see we’ve gone this far.”
For the first phase of the clinical trial, Kawaoka says he’s hopeful the vaccine is safe in humans and leads to “reasonably good” immune responses.
“After that, we need a company to take it to phases two and three,” he said. “That will involve hundreds of people and costs are going to go much higher.”
The Japanese government provided funding for the clinical trial in early 2018. Along with his position at UW-Madison, Kawaoka is also a professor of virology at the University of Tokyo.