Mothers with history of herpes can protect their offspring from neurological infection

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Adapted
Media Release
Pregnant women with a previous
history of herpes simplex virus type 1 (HSV-1) infection maintain active
antibodies against the virus, and researchers have found that this protection
can pass to the nervous systems of their offspring.
Using a mouse model of HSV-1
as well as autopsied samples of human adult and fetal tissues, investigators
from Dartmouth College’s Geisel School of Medicine found that antibodies
against HSV-1 produced by adult women or female mice could travel to the
nervous systems of their yet unborn babies, preventing the development and
spread of infection during birth. The work, published in mBio®, an online
open-access journal of the American Society for Microbiology, suggests that
immunizing pregnant women against HSV and similar infections could prevent
serious brain disease related to these conditions in fetuses and newborns, said
senior study author David A. Leib, Ph.D., professor of microbiology and
immunology at the medical school.
“Our results underscore
the previously underappreciated role of maternal antibodies in protecting fetal
and newborn nervous systems against infection,” Leib said. “Maternal
antibodies have a potent protective role in the neonatal nervous system against
HSV.”
While HSV-1 is commonly
associated with cold sores on the skin, the infection also can cause eye
infections and is the most common form of infectious corneal blindness in the
United States, Leib said. It also can enter the brain and cause inflammation
(encephalitis). HSV-1 infection in newborns – who can contract the virus from
infected mothers during passage through the birth canal – can be severe,
causing brain damage or death. Neonatal HSV infection affects an estimated 1 in
3,200 to 1 in 10,000 live births, Leib said. Even with antiviral intervention,
HSV causes significant brain disease in infants.
In a series of laboratory
experiments, the researchers found that antibodies against HSV-1 remain in the
trigeminal ganglion (a group of nerve cells that receives signals from the eyes
and face and is a key site of HSV infection) long after active virus infection
is cleared, and that these maternal antibodies can travel to the fetal trigeminal
ganglia. The investigators then showed that the antibodies completely protected
newborn mice against HSV infection.
“What this tells us is
that women who get pregnant who have a pre-existing herpes infection have a
mature immune response to that virus and will pass those antibodies to their
baby,” Leib said. “If that baby should be infected during delivery,
it will be protected because the mother’s antibodies get into its nervous
system before birth.” By contrast, if HSV-1 infection is acquired during
pregnancy, the risk of severe outcomes for the newborn can be as high as 50
percent.
Maternal antibodies providing
neural protection to the infants “hasn’t been noted before and is very
important for pathogens that infect newborns because there is often some kind
of neurologic consequence that may impact their entire lives,” added lead
study author Yike Jiang, an M.D./Ph.D. student at the medical school.
Several vaccines against HSV-1
tested in clinical trials for the prevention of adult-to-adult transmission
have failed, Leib noted, but none have been tested for prevention of adult-to-
baby so-called “vertical transmission” of the virus. Ongoing studies
in his lab are evaluating if any of the vaccines can protect against vertical
transmission. Maternal immunization may also be an effective strategy against
other pathogens that affect newborns, he said, such as Zika virus.
The study was supported by the
Munck-Pfefferkorn Education and Research Fund, the Geisel School of Medicine
and the National Institutes of Health.
SOURCE:
MEDICAL NEWS TODAY
Kayode Ojo
Kayode Emmanuel Ojo is the Co-Founder and Managing Director at SHEFFA Limited. He is presently studying Computer Science at the National Open University, Victoria Island, Lagos.