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| A healthy volunteer receives the NIAID Zika virus investigational DNA vaccine as part of an early-stage trial to test the vaccine’s safety and immunogenicity. This is the first administration of this vaccine in a human. Credit: NIAID |
The National Institute of Allergy and Infectious Diseases (NIAID) made a press announcement on
August 3,2016 about its recent launch of phase I clinical trials for its newly
developed DNA Zika vaccine.
Zika is rife
in Puerto Rico, American Samoa, the US Virgin Islands, and Florida and United States
department of defense(DoD) recently confirmed about 30 cases of Zika virus
infection among troops. As per Florida Department of Health recent update there
are 15 total number of non-travel related infections and 55 pregnant patients
have been infected due to either local transmission, sex with an infected
partner or travel.[1] A
total of more than 6,400 Zika cases have been reported in the US and its
territories.[2]
The NIAID
Zika virus vaccine is investigational and was developed in the beginning of
this year. The vaccine contains bio-engineered, non-infective Zika virus
plasmid that contains genetic code for protein of the Zika virus. When injected
into our body by intramuscular route, the DNA quickly assemble into a virus
like particle, that has lost its infecting capabilities. It incites an immune
response in the host by making antibodies and T cells.
The DNA vaccine,
is delivered on the site on skin via a short electrical pulse that propels the
DNA, which seeks human cells through a process
called electroporation.
It is also
known from the animal experiment that despite being genetically different, all strains
of the Zika virus have identical surface antigen, thereby vaccine developed
against one will be effective against others too. [3]
According to
John Mascola, MD, director of NIAID’s Vaccine Research Center (VRC), “DNA or
gene-based vaccines include antibodies, but they also can activate the
cell-mediated immune response, which ultimately could yield strong and durable
protection against disease.”
DNA vaccines
are new in the vaccine armament and no other DNA vaccine has been approved by
US.[4]
But since they do not need to grow live virus, DNA vaccines have short development
time.[5]
The vaccine
will be tested in 80 healthy volunteer in Maryland and Atlanta. The volunteers will
receive the first shot at the same time and then they are divided into 4 groups
of 20 each receiving the subsequent shots at varying intervals to study which
dosing schedule works best. All the participants will be closely monitored for 44
weeks of initial vaccine administration.[6]They
will be tested to measure the immune response to the vaccine at 18 and 24
months after the initial dose.
Researchers
have already tested the vaccines in animal studies and found them to be
effective and safe. When monkeys were exposed to Zika virus 4 weeks after the
second dose, they showed no clinical signs of infection nor the virus was found
in the blood.[7]
Meanwhile, a
similar vaccine developed by The Infectious Disease Research Centre (IDRC) and the Centre de
recherche du CHU (Centre hospitalier de l’Université) at Laval
University in Canada has also begin its phase 1 clinical trials.
The vaccine is
temporarily named GLS-5700, and is manufactured by Inovio, based in Plymouth
Meeting, Pennsylvania, and GeneOne Life Science, of Seoul, South Korea.
At this
point of time around 18 countries around the world are competing each other to
develop Zika virus vaccines including French pharmaceutical giant Sanofi SA and
GlaxoSmithKline.
According to
CDC Zika virus infection is a public health emergency because of its causation of
congenital birth defects. Currently 61 countries and territories are infected
with Zika virus and 12 countries have reported birth defects due to Zika.
If the phase
1 trial is successful, the vaccine will enter phase 2 trial in early part of
2017. But, even at this pace it will be another 2 years before it is
commercially available.
[1] http://www.floridahealth.gov/newsroom/2016/08/080316-zika-update.html
[2] https://www.niaid.nih.gov/news/newsreleases/2016/Pages/Zika-Investigational-Vaccine.aspx
[3] https://www.niaid.nih.gov/news/newsreleases/2016/Pages/Zika-serotype.aspx#
[4] https://www.statnews.com/2016/08/03/nih-zika-vaccine-trial/?trendmd-shared=0
[5] http://fortune.com/2016/01/28/zika-virus-vaccine/
[6] http://www.contagionlive.com/news/niaid-zika-vaccine-enters-clinical-trial
[7] https://www.niaid.nih.gov/news/newsreleases/2016/Pages/3-Zika-Vaccine-Approaches.aspx#
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