Army Research Produces Zika Vaccine Candidate in Record Time

By Annette M. Boyle

Nelson Michael, MD, PhD, director of the U.S. Military HIV Research Program at WRAIR and co-lead of the Zika program

Nelson Michael, MD, PhD, director of the U.S. Military HIV Research Program at WRAIR and co-lead of the Zika program

SILVER SPRING, MD—Drawing on deep experience with flaviviruses that started with its namesake’s research on yellow fever in the 1800s, the Walter Reed Army Institute of Research (WRAIR) and collaborators brought two Zika vaccine candidates through early testing in just four months this spring.

A recently inked agreement with Sanofi Pasteur will accelerate development, even as testing on humans begins in several locations.

The WRAIR team started discussing a Zika vaccine in January 2016 as a natural outgrowth of its work developing vaccines against other flaviviruses, such as yellow fever, dengue and Japanese encephalitis. Increasing reports of a denguelike illness from an Armed Forces Research Institute of Medical Sciences’ laboratory in Thailand over the previous three years had already drawn some researchers into studying Zika.

Three weeks into WRAIR’s vaccine development process, Dan Barouch, MD, PhD, of Harvard Medical School and Beth Israel Deaconess Medical Center contacted Nelson Michael, MD, PhD, director of the U.S. Military HIV Research Program at WRAIR and co-lead of the Zika program.

“He said, ‘I have three Brazilian post-docs that have made a challenge model they would like to test.’ We had a vaccine that needed a challenge,” Michael recounted. “We started experiments in April, wrote the paper Memorial Day weekend and submitted it over the holiday.” The results of their work, a study demonstrating that two different vaccines protected mice from the virus, appeared in Nature less than a month later.1

Environmental health technician, Pfc. Mary Pendris, Preventative Medicine, collects mosquito larval samples from standing water for testing. (Photo Credit: Lisa Phillips)

Environmental health technician, Pfc. Mary Pendris, Preventative Medicine, collects mosquito larval samples from standing water for testing. (Photo Credit: Lisa Phillips)

The rapid spread of the disease through South and Central America and into the U.S. spurred the team to move quickly. For the WRAIR researchers, the potential impact on warfighters and readiness provided additional impetus.

“We’ve already had one servicemember come back from deployment with it and pass Zika on to his wife,” Michael said. Zika virus infection during pregnancy can cause serious birth defects, including microcephaly.

The two candidate vaccines work in very different ways. The one developed by WRAIR is a purified Zika inactivated virus vaccine (ZPIV) based on a strain from Puerto Rico. The Harvard team developed a DNA vaccine using a strain of the virus from Brazil. Both vaccine candidates safely elicited an antibody response and protected mice against Zika challenges at four weeks and eight weeks after only one shot. No virus replication was detected in any of the vaccinated mice.

WRAIR has continued development of ZPIV, and both the Harvard group and another team at the National Institute of Allergy and Infectious Diseases (NIAID) are proceeding with DNA vaccines. WRAIR favors the purified inactivated virus vaccine over the DNA vaccine because it builds on “a flavivirus vaccine platform WRAIR previously developed which has been proven to be safe, effective, and able to meet regulatory requirements of the U.S. FDA,” explained Stephen Thomas, MD, PhD, the WRAIR Zika program lead. That might make the path to licensing and broader distribution smoother.

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