Last fall, the Wistar Institute announced it had achieved a 100% success rate in animal trials of a synthetic DNA vaccine against the Zika virus. Now the vaccine has notched another success—this time in a phase 1 trial in people who received up to three injections of the compound.
Two weeks after volunteers for the trial received the final dose, they all developed Zika-specific antibodies and 80% of them developed neutralizing antibodies, which help cells defend against pathogens, according to a statement. There were no significant side effects. The trial was conducted in partnership with the Perelman School of Medicine at the University of Pennsylvania, Inovio Pharmaceuticals and GeneOne Life Science.
Synthetic DNA vaccines work by instructing the body to mount an immune response to a foreign invader. The Zika vaccine, called GLS-5700, produces a response against a specific antigen—in essence rallying antibodies and T cells in the immune system to neutralize the virus. After each dose, trial participants were given electroporation, or small electric zaps on their skin at the injection site, which was meant to improve vaccine uptake.
In the earlier animal trials, GLS-5700 prevented Zika from invading the brain. That could prove significant, in light of the fact that the biggest risk of the virus is that it can cause the brain defect microcephaly in infants.
Inovio and GeneOne are among more than a dozen life science companies that are racing to develop Zika vaccines. Other players include GlaxoSmithKline, which is working with the National Institutes of Health on a technology called self-amplifying mRNA (SAM). Like DNA technology, SAM does not rely on using attenuated versions of live viruses, like most vaccines do.
At least one potential competitor is out of the race, however. Sanofi was working on a vaccine called Zika purified inactivated virus (ZPIV), which was initially developed by the U.S. Army’s Walter Reed Army Institute of Research. But in September, the U.S. Department of Health and Human Services’ Biomedical Advanced Research and Development Authority (BARDA), retreated from the development project, prompting Sanofi to pull the plug on its Zika vaccine development efforts.
GLS-5700 was developed in a few short months, according to David Weiner, director of Wistar’s Vaccine & Immunotherapy Center. That could be an important advantage of DNA vaccines, he added, particularly when dealing with viruses that can mutate over time. The platform, he said in the statement, “has advantages in temperature stability, storage, dose and distribution compared to most traditional vaccines, making DNA vaccines an important tool to respond quickly to curb an emerging epidemic.”
The vaccine will need further testing to fully determine efficacy, the research team says. But they believe the DNA technology could be used to create vaccines against many other diseases, including Ebola, West Nile virus and pandemic flu.