By Patricia Reaney
LONDON (Reuters)
- A new vaccine that protects monkeys against the deadly Ebola
virus could lead to the development of a similar one for humans,
scientists said on Wednesday.
Ebola is a
terrifying disease that causes high fever, massive internal bleeding
and death usually within seven to 21 days of infection. It strikes
quickly and unexpectedly and kills 90 percent of its victims.
Hundreds of people have died in recent outbreaks.
A team of
scientists, led by researchers at the National Institutes of Health
(NIH) in the United States, has successfully vaccinated four monkeys
against what would be a lethal dose of the virus.
``We don't
know if this model perfectly replicates what happens in humans.
It remain an open question whether this vaccine strategy will
be successful in humans,'' Gary Nabel, of the Dale and Betty Bumpers
Vaccine Research Center at the NIH, said in a telephone interview.
``It will
serve as a model to give us the scientific information that we
need to learn how to develop the vaccine,'' he said.
Three Strains
Of Ebola Virus
The vaccine
uses strains of DNA containing genes that encode Ebola virus proteins
to induce an immune response. The researchers also boosted that
response by including a weakened strain of a different virus in
the vaccine.
Nabel and
his team, whose research is published in the science journal Nature,
said the four monkeys injected with the vaccine were protected
from the virus and were still free of infection six months later.
``Ebola is
a difficult virus because currently available antiviral drugs
have no proven effect on it and we do not know its natural reservoir,
making environmental control impossible,'' said Dr Anthony Fauci,
director of the National Institute of Allergy and Infectious Diseases
at the NIH.
``A vaccine
is therefore the best hope for protecting humans from infection,
and this study makes some key advances toward realizing that goal,''
he said.
A human vaccine
will have to protect against the three known fatal Ebola strains
-- Zaire, Sudan and Ivory Coast.
The vaccine
tested on the monkeys includes genes encoding proteins from the
three strains of the virus.
``We of course
want to test the multivalent vaccine for effectiveness against
all three strains of Ebola but we also need to look more closely
at the immune response induced by these vaccine so we can nail
down what is needed for protection,'' said Dr Nancy Sullivan,
who worked on the project.
The Ebola
virus was first identified in 1976. It emerged from an unknown
source, which scientists suspect was an animal, and caused outbreaks
in Sudan and the former Zaire.
Isolated outbreaks
have occurred since then, most recently in Uganda where the Sudan
strain had killed 129 people, as of November 24.
The virus
is extremely infectious and spread through direct physical contact.
It can be transmitted through a handshake, coughing or sneezing.
``Time will
tell whether this is a vaccine that has success in people. The
results of the study encourage us to pursue this as a vaccine
candidate in humans,'' Nabel said.
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