- Zika virus is a mosquito-borne flavivirus that is a threat
especially to pregnant women
- Scientists and pharmaceutical companies have been conducting
studies to find a vaccine against the virus
- Plant-based vaccine against Zika virus has been developed by a
research team at the Arizona State University
- The vaccine could be more potent, safe and cost-effective than
any other alternative to date
A research team
at the Arizona State University (ASU) has taken a significant step in boosting
the efforts to prevent Zika virus, which affects pregnant women and babies are
born with severe brain birth defects. The world's first plant-based Zika
vaccine developed by ASU Biodesign Institute scientists is more potent, safer
and cheaper to produce.
Chen, a scientist at the Biodesign Center for IVV and professor in the School
of Life Sciences, "Our vaccine offers improved safety and potentially
lowers the production costs more than any other current alternative, and with
equal effectiveness. We are very excited about these results."
‘The plant-based vaccine uses the smallest and unique part of the Zika virus that can induce a potent and robust immune response.
have shown promising
results in the early animal and human trials. In 2016, the Food and Drug
Administration approved the first human testing of a Zika vaccine candidate and
a $100 million U.S. government-led clinical trial is underway. However,
currently, there are no licensed vaccines available to combat Zika virus.
Now, a research
team led by Chen have come up with a better vaccine candidate based on a key
Zika protein. For the past decade, Chen has worked on plant-based therapeutics
and vaccines against West Nile virus and Dengue which come from the same Zika
family called flaviviruses.
Vaccine Targeting the Zika Protein
To date, many
scientists have tested several kinds of Zika vaccines on mice, including one
made from DNA and another from an inactivated form of the virus. A
single dose of both the vaccines was
effective to induce antibodies that protected the animals from becoming
infected when they were exposed to the virus. The heat-killed vaccine can
increase the risk of accidentally injecting a live version of the virus due to
an error made in the vaccine production protocol.
Chen and his
team have been producing low-cost vaccines in plants to fight devastating
infectious diseases. For the current study, the team investigated a vaccine
against a part of a Zika virus protein called DIII,
which plays a key role for the virus to infect people. All the flaviviruses
have an envelope protein on the outside part of the virus. It has three
III has a unique stretch of DNA for the Zika virus, and we exploited this to
generate a robust and protective immune response that is unique for Zika,"
team grew the envelope protein in bacteria, then switched to prepare the
DIII protein domain in tobacco plants.
In a mouse model,
the research team performed immunization experiments, which induced antibody
and cellular immune responses that have been shown to confer 100 percent
protection against multiple Zika virus strains.
team used the complete Zika envelope protein for their vaccine for the second
group. Envelope protein domains I, and II are similar to West Nile and
dengue viruses, and this can cause a dangerous cross-reactive immune response.
make the full native envelope protein as the basis for a vaccine, it will
induce antibodies against DI, DII and the DIII domains of the protein. Those
who have been prior exposed to DI and DII of other members of the Zika virus
family may be prone to developing very bad symptoms, or in some cases,
fatalities for dengue," explained Chen.
conducted animal studies have shown that prior exposure to dengue or West Nile
virus can worsen the infection and symptoms of Zika virus. In men, prior
exposure to dengue can increase the likelihood of sexual transmission.
vaccine uses the smallest and unique part of the Zika virus that can produce a
potent and robust immune response. The research team used a pseudovirus (fake
virus) that displays only the DIII part of the envelope protein on the surface.
Chen said that this is the potent vaccine than other previous vaccine versions.
confident that his DIII-based protein vaccine will be potent, safer and
"We did a
test to make sure that the vaccine produces a potent protective immune
response, but also, that it does not produce antibodies that may be cross
reactive for dengue, West Nile, yellow fever or others," said Chen.
"This is an
excellent example of the brightest minds quickly coming together, with public
support, to take on one of the most significant public health challenges of our
time. That's the essence of Biodesign at its best, and we hope this important
proof-of-principal of a Zika vaccine can be translated quickly into the
clinic," said, Josh LaBaer, executive director of the Biodesign Institute.
we have to ensure the utmost safety of any Zika vaccine, especially because the
people who will need it most, pregnant women, have the most worries about their
health, and the health of the fetus. This has to be 100 percent safe and
effective," said Chen.
Chen hopes to
begin the first phase of a human clinical trial in the next two years. The
findings of the study is published in the journal Scientific
is a self-limiting febrile illness with symptoms of a headache,
rash, and myalgia. Zika is primarily transmitted by daytime mosquitoes. But
other routes of transmission include sexual transmission.
During the Zika
pandemic, women were told not to become pregnant because babies were born with
a severe brain defect called microcephaly, in which the head and brain is
underdeveloped. There have also been cases of vision and hearing defects and
learning disabilities associated with the severity of the infection.
is a serious complication that occurs due to Zika virus infection. It is an
immune-mediated disease affecting the peripheral nervous system, leading to a
severe peripheral neuropathy. This can cause muscle paralysis and can result in
death in some cases.
- Ming Yang, Huafang Lai, Haiyan Sun and Qiang Chen. Virus-Like Particles That Display Zika Virus Envelope Protein Domain III Induce Potent Neutralizing Immune Responses In Mice. Scientific Reports (2017). DOI:10.1038/s41598-017-08247-9