DNA-based vaccine guards against Zika in monkey study

September 22, 2016 by Dennis Thompson, Healthday Reporter

An experimental DNA-based vaccine protected monkeys from infection with the birth defects-causing Zika virus, and it has proceeded to human safety trials, researchers report.

"The universally elicited antibodies from all primates, but for the animals that got a full dose of vaccine, 17 of 18 were protected from infection," said study co-author Ted Pierson. He is chief of the Viral Pathogenesis Section at the U.S. National Institute of Allergy and Infectious Diseases.

Based on these findings, researchers have begun clinical safety trials in healthy human beings, Pierson said. These trials will show whether the vaccine is safe in humans, and whether it prompts an immune system response as it did in monkeys.

"When a vaccine is effective in a lower primate species, it is a good signal that it will be effective in humans," said Dr. Amesh Adalja, a senior associate at the University of Pittsburgh's UPMC Center for Health Security in Baltimore. "The NIH vaccine candidates have cleared an important hurdle, and we are awaiting results from phase 1 human studies."

However, animal research does not always pan out in humans.

Zika is the first mosquito-borne virus known to cause terrible birth defects, most of them brain-related. The most common defect is microcephaly, in which a child is born with an abnormally small brain and skull. Thousands of babies have been born with Zika-linked microcephaly, most of them in Brazil, since an outbreak began in South America in April 2015.

Zika infections have been occurring in south Florida, with 43 cases as of Sept. 21, according to the federal Centers for Disease Control and Prevention. There have been no reports of microcephaly in the state.

Because of the ongoing transmissions, a Zika vaccine is important to prevent future birth defects, Adalja and Pierson said.

This potential vaccine contains a piece of DNA created synthetically in the laboratory from the Zika virus, Pierson said.

When introduced into the body, the DNA causes small virus-like particles to be secreted from cells, Pierson explained. These particles are not full-fledged Zika, but are similar enough to the virus that the immune system might produce an antibody response that will also protect against Zika.

"This kind of vaccine, which we call a DNA vaccine, there's precedent for this," Pierson said, noting that similar technology was used years ago to create a for West Nile virus.

To test the potential effectiveness of the Zika vaccine, researchers provided a single dose to six rhesus monkeys and two shots to 18 monkeys.

None of the monkeys that received a single dose was protected from Zika infection, but the vaccine did appear to create an antibody response, the researchers found. Their blood contained less Zika virus than animals who did not receive the vaccine.

The two-dose vaccine series protected 17 out of the 18 monkeys against exposure to Zika, and provided researchers with an idea of how much antibody response is needed to protect against infection.

"The DNA vaccines leading the way in the Zika vaccine rush are an important innovative development, and would represent the first commercially available DNA vaccines if proven to be effective and safe," Adalja said.

This vaccine could protect fetuses against Zika by creating an immune response in pregnant women that prevents a full-fledged viral infection, Pierson said. The vaccine is not expected to cause Zika-like birth defects itself, because it does not cause Zika infection.

"The reason why there are Zika-associated neurodevelopmental defects is because the virus is actually infecting the fetus and attacking developing neurons in the fetus, causing direct harm," Pierson explained. "The neurodevelopmental defects are a result of what the viral infection is doing, not a result of the body's immune response."

It's unclear when this or some other Zika vaccine will be available for use. Any vaccine candidates will have to be tested during a future Zika outbreak, to see whether it is able to protect people against active viral transmission, Pierson said.

Adalja added that other potential Zika vaccines are in earlier stages of development, including an inactivated virus approach at Walter Reed National Military Medical Center in Bethesda, Md., and RNA vaccines under development by two private companies.

The findings on the DNA vaccine were published Sept. 22 in the journal Science.

Explore further: Pennsylvania firm launches Zika vaccine trial in Puerto Rico

More information: Paper: "Rapid Development of a DNA Vaccine for Zika Virus," Science science.sciencemag.org/lookup/ … 1126/science.aai9137

The U.S. Centers for Disease Control and Prevention provides more information on mosquito-borne diseases.

This Q & A will tell you what you need to know about Zika.

To see the CDC list of sites where Zika virus is active and may pose a threat to pregnant women, click here.

Related Stories

Pennsylvania firm launches Zika vaccine trial in Puerto Rico

August 29, 2016
A Pennsylvania drug company announced Monday that it has launched a clinical trial of an experimental Zika vaccine in Puerto Rico, the part of the U.S. hardest hit by the mosquito-borne virus.

Research provides clues to how Zika virus breaches the placental barrier

September 15, 2016
New research reveals that in pregnant women, Zika virus infection damages certain cells that affect placental formation and function. Furthermore, herpes simplex virus-2 (HSV-2) infection augments placental sensitivity to ...

France's Sanofi to work with US Army on Zika vaccine

July 6, 2016
French pharmaceuticals group Sanofi said Wednesday it would work with the US Army's Walter Reed Institute to develop a potential vaccine against the mosquito-borne Zika virus, linked to brain damage in newborns.

Antibodies from dengue virus survivors can be used to prevent Zika infection

July 28, 2016
A new research study from University of North Carolina researchers shows that individuals who have been previously infected with a flavivirus – specifically dengue and Zika viruses – could have antibodies that protect ...

Experimental Zika vaccine to begin human testing

June 20, 2016
An experimental vaccine for the Zika virus is due to begin human testing in coming weeks, after getting the green light from U.S. health officials.

Recommended for you

Scientists find key to regenerating blood vessels

November 23, 2017
A new study led by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) identifies a signaling pathway that is essential for angiogenesis, the growth of new blood vessels from pre-existing vessels. The ...

Surprising roles for muscle in tissue regeneration, study finds

November 22, 2017
A team of researchers at Whitehead has illuminated an important role for different subtypes of muscle cells in orchestrating the process of tissue regeneration. In a paper published in the November 22 issue of Nature, they ...

Study reveals new mechanisms of cell death in neurodegenerative disorders

November 22, 2017
Researchers at King's College London have discovered new mechanisms of cell death, which may be involved in debilitating neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease.

Cinnamon turns up the heat on fat cells

November 21, 2017
New research from the University of Michigan Life Sciences Institute has determined how a common holiday spice—cinnamon—might be enlisted in the fight against obesity.

How rogue immune cells cross the blood-brain barrier to cause multiple sclerosis

November 21, 2017
Drug designers working on therapeutics against multiple sclerosis should focus on blocking two distinct ways rogue immune cells attack healthy neurons, according to a new study in the journal Cell Reports.

New simple test could help cystic fibrosis patients find best treatment

November 21, 2017
Several cutting-edge treatments have become available in recent years to correct the debilitating chronic lung congestion associated with cystic fibrosis. While the new drugs are life-changing for some patients, they do not ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

TheGhostofOtto1923
not rated yet Sep 22, 2016
DNA vaccines. This is genetic engineering isn't it? And does this bring us closer to the possibility of using communicable viruses to engineer populations in bulk?

And can we use it to eradicate persistent infections such as hepatitis, herpes, t gondii, or that Tasmanian devil tumor disease?
gculpex
not rated yet Sep 22, 2016
We've have been doing DNA vaccines for decades....

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.