Health

Zika vaccine shows promising results


Dr In-Jeong Kim said: “The vaccine has been shown to be safe for non-pregnant people, but of course we need to know if it is safe and effective for those most at risk: women pregnant women and their unborn children. a viral immunologist at the Trudeau Institute and first paper author. “Our proof-of-concept studies conducted at Trudeau and Texas Biomed show very promising results that vaccines given before pregnancy provide a high level of protection for mothers and babies. born.”

The 2015-2016 Zika outbreak in Brazil and other countries in the Americas caused an increase in the number of miscarriages and certain birth defects, known as Congenital Zika Syndrome, which includes abnormal microcephaly. common and neurodevelopmental disorders. This led the World Health Organization to declare the Zika outbreak a public health emergency of international concern.

“It is important to test vaccines before the next big outbreak, because there will be another one,” said Jean Patterson, PhD, virologist at Texas Biomed and senior author of the paper. . “Zika is part of a family of viruses known to be cyclical. These viruses tend to spread rapidly through populations among people who have never been exposed to the virus before, then in numbers. the number of infections decreased over the years as most people were exposed.As more and more people were born, there was a new group of individuals in which the virus could once again wreak havoc. break that cycle.”

The purified, inactivated Zika vaccine (ZPIV) candidate was developed by a team at WRAIR using the same technology they used to develop the Japanese encephalitis vaccine. The vaccine has been tested in non-pregnant animals, showing it to effectively remove the virus from the blood. In Phase 1 human trials, it was shown to be safe and induce a protective immune response.

However, the rigorous testing that proves vaccines protect women and their fetuses from serious infections and birth defects is limited for ethical and safety reasons. That’s where the animal models come in.

The Trudeau Institute and Texas Biomed evaluated the vaccine in pregnant mice and rats, respectively. Studies in mice led by Kim and Marcia Blackman, PhD, a viral immunologist at Trudeau, have demonstrated that the vaccine prevents about 80% of birth defects, and the antibodies are potentially fatal. Viral activation was detected in fetal blood samples eight days after infection.

“We were able to detect maternal antibodies in the fetus during pregnancy, and the results suggest that these antibodies play an important role in protecting the fetus from the Zika virus,” said Kim. .

Marmosets, which are small primates, are more susceptible to Zika infection than other non-human primates; Previous studies have shown that fetuses are aborted within two weeks of maternal infection.

In the present study, four marmosets were immunized with ZPIV vaccine. After becoming pregnant, they were exposed to the Zika virus. Only 1 out of 12 animals tested positive for Zika virus, proving to be more than 90% effective.

“Because animals become pregnant at different times, our study was able to show that vaccines offer protection for at least 18 months after vaccination, which is very important,” said Patterson. important for demonstrating long-term immunity,” says Patterson.

Researchers are testing what happens when the vaccine is given during pregnancy.

“Along with early-stage clinical trials, we believe these data support even more that this vaccine platform is a viable approach to combat the persistent threat of Zika. ”

Contributors to the npj Vaccines article also include: University of Illinois Chicago; University of California, Davis; University of California at San Francisco; and the State University of New York, Upstate College of Medicine.

The study was supported by the Department of Defense and the Office of the Director, National Institutes of Health P51OD011133.

Source: Eurekalert



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