Zika vaccine shows promising results in preclinical studies

Date:
January 27, 2022
Source:
Texas Biomedical Research Institute
Summary:
A Zika virus vaccine candidate is effective at preventing the Zika
virus passing from mother to fetus in preclinical animal studies,
according to a new study.



FULL STORY ==========================================================================
A Zika virus vaccine candidate is effective at preventing the Zika virus passing from mother to fetus in preclinical animal studies, according
to a new study in the journal npj Vaccines.


==========================================================================
The research is a collaboration between Trudeau Institute, Texas
Biomedical Research Institute's Southwest National Primate Research
Center (SNPRC), and Walter Reed Army Institute of Research (WRAIR),
where the vaccine was developed.

"The vaccine has been shown to be safe for non-pregnant humans, but of
course we need to know if it is safe and effective for the people at
greatest risk: pregnant women and their fetuses," says In-Jeong Kim, PhD,
a viral immunologist at Trudeau Institute and the first paper author. "Our proof-of-concept studies conducted at Trudeau and Texas Biomed show very promising results that the vaccine given before pregnancy will provide
high levels of protection for mothers and babies." The 2015-2016 Zika
outbreak in Brazil and other countries in the Americas caused a surge
in miscarriages and a constellation of birth defects, called Congenital
Zika Syndrome, including abnormally small heads and neuro- developmental disorders. This prompted the World Health Organization to declare the
Zika outbreak a public health emergency of international concern.

"It's important to test vaccines before the next large outbreak, because
there will be another," says Jean Patterson, PhD, a virologist at Texas
Biomed and a senior paper author. "Zika is part of a family of viruses
known to go through cycles. These viruses tend to spread rapidly through
nai"ve populations that have never been exposed to the virus before, then infections drop down for years because most people have been exposed. As
more and more people are born, there is a new group of nai"ve individuals
in which the virus can once again wreak havoc. We want to help 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 a Japanese encephalitis vaccine. The vaccine has been tested
in non-pregnant animals, showing it effectively clears the virus from
blood. In Phase 1 human trials, it has been shown to be safe and elicit
a protective immune response.



========================================================================== However, running rigorous tests to prove the vaccine protects women and
their fetuses from both infection and severe malformations is restricted
due to ethical and safety reasons. That's where animal models come in.

Trudeau Institute and Texas Biomed evaluated the vaccine in pregnant
mice and marmosets, respectively. The mouse studies, led by Kim and
Marcia Blackman, PhD, a viral immunologist at Trudeau, demonstrated
the vaccine prevented about 80% of fetal malformations, and antibodies
capable of neutralizing the virus were 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 the antibodies play a critical role in protecting fetuses from Zika virus," Kim says.

Marmosets, which are small primates, are more sensitive to Zika infection
than other nonhuman primates; previous studies showed fetuses were
aborted within two weeks of maternal infection.

In the current study, four marmosets were immunized with the ZPIV vaccine.

After they became pregnant, they were exposed to Zika virus. Only 1 of
12 offspring tested positive for Zika virus, demonstrating more than 90% effectiveness.



========================================================================== "Because the animals became pregnant at different times, our study was
able to show the vaccine confers protection for at least 18 months after vaccination, which is important for showing long-lasting immunity,"
Patterson says.

The researchers are already testing what happens when the vaccine is administered during pregnancy.

"These studies add evidence that the Zika vaccine WRAIR developed
not only protects animals against Zika virus infection, but also
the congenital defects that mimic what has been observed in people,"
says Kayvon Modjarrad, MD, PhD, who leads the U.S. Army Zika vaccine
program and is the Director of the Emerging Infectious Diseases Branch
at WRAIR. "Together with the early phase clinical trials, we believe
these data lend even more support that this vaccine platform is a viable approach for countering the persistent threat of Zika." Collaborators on
the npj Vaccinespaper also include: University of Illinois Chicago;
University of California, Davis; University of California at San
Francisco; and State University of New York, Upstate Medical University.

The research is supported by the Department of Defense and the Office
of the Director, National Institutes of Health Grant P51OD011133.

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========================================================================== Journal Reference:
1. In-Jeong Kim, Paula A. Lanthier, Madeline J. Clark, Rafael A. De La
Barrera, Michael P. Tighe, Frank M. Szaba, Kelsey L. Travis,
Timothy C.

Low-Beer, Tres S. Cookenham, Kathleen G. Lanzer, Derek T. Bernacki,
Lawrence L. Johnson, Amanda A. Schneck, Corinna N. Ross, Suzette D.

Tardif, Donna Layne-Colon, Stephanie D. Mdaki, Edward J. Dick, Colin
Chuba, Olga Gonzalez, Kathleen M. Brasky, John Dutton, Julienne N.

Rutherford, Lark L. Coffey, Anil Singapuri, Claudia Sanchez San
Martin, Charles Y. Chiu, Stephen J. Thomas, Kayvon Modjarrad,
Jean L. Patterson, Marcia A. Blackman. Efficacy of an inactivated
Zika vaccine against virus infection during pregnancy in mice and
marmosets. npj Vaccines, 2022; 7 (1) DOI: 10.1038/s41541-021-00426-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220127172622.htm

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