Researchers from the Duke Human Vaccine Institute have helped develop a vaccine for the Zika virus using modified genetic material.
The Zika virus is spread through mosquito bites and most commonly occurs in Africa and Asia. Previously, there were no treatments for the infection except for painkillers to alleviate symptoms. The new vaccine, which is currently undergoing clinical trials with human subjects, has already proven to be very effective in primates and monkeys.
The project was a collaboration with researchers at the University of Pennsylvania and the National Institute of Allergy and Infectious Diseases.
“The vaccine works because it targets the molecule in the Zika virus to which antibodies that can neutralize the virus bind,” said Barton Haynes, Frederic M. Hanes professor of medicine and director of the Duke Human Vaccine Institute.
After hearing about a new immunization platform developed by Drew Weissman, professor of medicine at the University of Pennsylvania, Haynes approached Weissman to try it on primates. Haynes intended to use the genetic immunization method to develop an HIV vaccine, and inadvertently discovered its effectiveness on Zika.
“We wanted to know if [Weissman’s] immunization would work in primates and monkeys, and the genetic material that he had most readily available was the Zika [virus] genetic material, and so we tried it," Haynes said. "It worked so well that we decided to challenge the monkeys with Zika, and they were 100 percent protected.”
The vaccine uses modified messenger RNA that prompts immunogen production against the virus. The genetic nature of the vaccine makes it applicable not only to Zika, but also to HIV, malaria, hepatitis C, tuberculosis and other viruses.
“The properties of the RNA that we developed are that it gives you very high and a long duration of protein production, so we put the immunogen in the RNA so when we inject the RNA into an animal, the RNA makes Zika immunogen," Weissman said.
If approved, the treatment would be the first Zika vaccine to provide long-term protection against the disease without using a live virus.
"What our thought was is that having an extended duration of protein production along with the lack of inflammatory activity of the mRNA—when you inject the RNA, it doesn’t induce inflammatory mediators—the combination of those two things would lead to a better immune response,” Weissman said.
Weissman noted that the vaccine's principal modification was a uridine base exchange in the RNA, which allowed it to be translated “about a thousand times better by cells in the body than by the standard uridine-containing RNA.”
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