"We found that this antibody not
only neutralizes the dengue virus but, in mice, protects both adults and
fetuses from Zika disease," said Michael S. Diamond, MD, PhD, the Herbert
S. Gasser Professor of Medicine and the study's senior author.
Significance of Antibody that Offers Dual Protection
to the study team, since both dengue
and Zika virus
are caused by related
viruses, they believed that an antibody effective against dengue infection
could possibly also be effective against Zika virus infection. Such an antibody
could be of great use in regions such as Brazil where incidence of both
infections is high and could protect pregnant women and their babies, who form
an especially vulnerable group.
‘Early administration of an anti-dengue antibody to a pregnant woman can protect her as well as her fetus from dengue and Zika virus infection during pregnancy.
this end, Diamond and graduate student Estefania Fernandez
worked with Gavin Screaton, MD, DPhil, of Imperial College London, who had earlier
created a panel of human anti-dengue antibodies.
Testing the Efficacy of Dengue Virus Antibody Against Zika Virus Infection In Mice
The team proceeded to infect nonpregnant adult mice with Zika virus followed by administration of one of the anti-dengue antibodies on days 1, 3 and 5 after infection. For comparison, another group of mice was infected with Zika virus, but given a placebo instead of the antibody.
three weeks following infection, more
than 80 percent of the untreated (placebo) mice had died, while all of
the mice that had been given the anti-dengue antibody within three days of
percent of the mice that received the antibody on day 5 of infection
The study team further wished to
determine whether the antibody could also protect fetuses from infection.
They infected pregnant female mice on day 6 of their pregnancies with Zika
virus followed by a dose of antibody or a placebo, one or three days
week later, on the 13th day of gestation, the amount of Zika's genetic
material was shown to be 600,000 times lesser in the placentas and 4,900
times lower in the fetal heads in mice that had received antibody on day 1
of infection, when compared to mice that had been given placebo.
administering the antibody three days after infection was not as
effective: The quantum of viral genetic material in the fetal heads was
only decreased nineteen fold and that in the placentas twenty-threefold.
These findings suggest that antibody administered soon after infection effectively
protects both mother and fetus
from serious effects of Zika virus
However, since a woman may not be aware
when she became infected, it would be reasonable to administer the antibody as
soon as she is aware that she is pregnant.
of the Study
Currently there is no effective treatment
or vaccine to prevent Zika virus infection. Giving this antibody as a drug to a
pregnant woman could ensure that both she and her fetus are protected for the
duration of pregnancy. The important factor would be to make sure that
there are sufficient levels of
antibody in the mother's blood that can protect her throughout
Dengue and Zika Virus Infection - In Brief
Dengue fever is a viral illness spread by
mosquito bites. It is marked by fever, headaches, severe muscle and joint pain
with possible serious consequences in infected individuals. However, the virus
does not attack the fetus.
Zika virus infection is caused by a
related virus and also spreads by the bite of an infected mosquito.
Zika virus causes moderate to severe illness in a pregnant woman, but more
importantly attacks the fetus resulting in congenital abnormalities of the
brain such as microcephaly.
Against Future Dengue Infection with a Different Strain
Presence of dengue virus antibodies in
the bloodstream for months on end could pose a
serious threat, because antibodies that protect against one strain
of dengue virus could cause serious life threatening illness if the
person is infected by another dengue strain
. To ensure that this does not
happen, the scientists tweaked the antibody in four places, rendering it
impossible for the antibody to make dengue worse.
"We mutated the antibody so that it
could not cause antibody enhancement of dengue infection, and it was still
protective," said Diamond, who is also a professor of pathology and
immunology, and of molecular microbiology. "So now we have a version of
the antibody that would be therapeutic against both viruses and safe for use in
a dengue-endemic area, because it is unable to worsen disease."
and colleagues are working on determining the dose of the antibody a
pregnant woman would require to ensure that her fetus is effectively
protected throughout pregnancy.
are also working on ways to prolong the half-life of the antibody in the
bloodstream, in order to reduce the number of
doses of antibody injections needed.
In conclusion, an antibody that
simultaneously protects against both these serious infections while the
woman is pregnant, would be most welcome, especially in areas with
a high prevalence.
- Zika Virus - (https://www.cdc.gov/zika/transmission/index.html)
- Dengue fever - (https://en.wikipedia.org/wiki/Dengue_fever)