The World Health Organization declared it a global public health emergency in February, and it now looks like a heightened response to the Zika virus is starting to bear fruit. The US Food and Drug Administration (FDA) has just approved the first human trials of an experimental Zika virus vaccine, with the first subjects set to receive doses in the coming weeks.
From joint pain, fevers and rashes to very serious complications like birth defects, the symptoms and rapid spread of the Zika virus has brought a lot of attention to the potential value of a vaccine. But developing a vaccine is an involved process that requires research into how a virus replicates and how the immune response can protect against it, so developing a quick-fix is generally anything but straightforward.
In any case, a new drug called GLS-5700 has been cleared for human testing and will be given to 40 healthy people in an upcoming phase 1 human trial. US pharmaceutical company Inovio has partnered with South Korean company GeneOne Life Science to develop a DNA vaccine, which has been tested on small and large animal models where it triggered a "robust" antibody and T cell response.
Developing a DNA vaccine is the same approach being taken by the US National Institute of Allergy and Infectious Diseases, which aims to begin human trials for a Zika vaccine later in the year. These types of vaccines differ from live vaccines that contain entire organisms or parts of them, which work to train the immune system to fend off future germ invasions.
"In this case they are not delivering the organism, they are just delivering the genetic information for the organism," Jason Mackenzie Associate Professor at the University of Melbourne's Department of Microbiology and Immunology, explains to Gizmag. "So the coat, if you like, of the virus gets made and stimulates the immune response to trigger that memory and give you immunity. So it's safer in a way, because you're not giving any sort of live organism, you are just giving DNA. It is a lot more stable and cold storage isn't a problem, so there are a few advantages to DNA vaccine approaches."
Inovio and GeneOne Life Science plan to kick off the trial in the coming weeks, in which they will be assessing the safety, tolerability and immunogenicity of GLS-5700. They expect to report interim results later in the year. As the trial only involves 40 subjects, it is still early days on the long road to full regulatory approval, but the fast-tracking of vaccine development in response to public health emergencies is something that has happened before.
"We saw that with the Ebola situation, a number of those vaccines were fast-tracked because of the urgency that was required and the impact of the disease itself," says Mackenzie. "Ebola has a high mortality rate, so there was a real need to get the vaccine out. Zika probably doesn't have that huge impact, but it's obviously got some pretty severe complications."