A joint effort should help hasten the effort to find a vaccine for humans as quickly as possible to respond to the ongoing emergency posed by the virus.
Walter Reed's Zika purified inactivated virus vaccine technology will be transferred to Sanofi. The institute will also share data, biologic samples generated during completed non-human primate studies and biologic samples generated during its own safety studies.
Sanofi hopes to produce an effective "killed" vaccine swiftly as another company, Inovio Pharmaceuticals, races to the finish line with its own DNA vaccine. Other researchers are also working on a possible Zika vaccine.
"We're working on the inactivated vaccine approach, which we think is more directly applicable," said Dr. Jon Heinrichs, Sanofi's R&D project lead for Zika, explaining that his team believes its tactic can produce a vaccine with potency over time.
Inactivated vs. DNA vaccine
To create an inactivated vaccine
, scientists kill the disease-causing microbe to create a vaccine that is more stable than live vaccines and safer too, since the dead microbes can't mutate back to their disease-causing state. By contrast, DNA vaccines introduce the genes of a microbe's antigens into the body, which produces an immune response, as a way to induce the production of antigens within cells. Though promising, these DNA vaccines are still in an experimental stage.
The research agreement between Sanofi and Walter Reed is not a first. According to Heinrichs, the two organizations have worked together on a number of programs, including a dengue virus vaccine. More important, both have long experience with this particular virus type.
"Zika is a flavivirus, and we've been working on flaviviruses for over a hundred years," said Dr. Stephen Thomas, Zika program lead at the Walter Reed Army Institute of Research.
Thomas, an infectious-disease physician, and his team have been tracking the uptick in global Zika virus infections and began work on what they believed would be a viable vaccine candidate. Their preliminary research will be the basis for more advanced work to be performed by Sanofi, a global company that is also familiar with flavivirus vaccines.
The pharmaceutical giant markets three flavivirus vaccines and will now apply that expertise to the Zika virus, according to Heinrichs.
"The fact that we've been conducting studies in Latin America for a long time enables us to move very quickly in that space and move quickly on Zika," Heinrichs said, adding that researchers have access to clinical sites and patients serums on which they might perform the necessary complex experiments.
Protecting service members
The Walter Reed institute had been conducting experiments on strains of Zika gathered in the Philippines and Thailand. As Thomas explained, thousands of service members, including women of child-bearing age, are deployed in places where Zika is actively transmitted, so it is a Department of Defense concern. After all, the Centers for Disease Control and Prevention says the deadliest animal in the world is the mosquito, due to its disease-spreading abilities.
The CDC provided Walter Reed with a strain from Puerto Rico, and from there, Thomas and his team "killed it and purified it" and then conducted other processes to create an inactivated vaccine.
"We took a playbook we had run before and applied it to the nuances of Zika," Thomas said, noting that the new Zika vaccine candidate is similar to the institute's licensed vaccine for another flavivirus, Japanese encephalitis.
According to Thomas, the institute works on the "upstream side" of things and then teams up with a corporate partner to do the "downstream" or "big manufacturing" side of things. It's one thing to pilot a vaccine in a small lab, create 1,000 doses and then test it, he said, but "it's a completely different thing to produce it at a 100 million doses." And that's where Sanofi comes in.
Heinrichs did not comment on a timeline for a finished product, since making a vaccine is an "iterative process. We learn from the experiments, and then we move forward." Among the positives with regard to creating a Zika vaccine is the fact that early research suggests creating a vaccine to protect against one strain of the virus should also protect against all the strains seen around the world.