MORE than 50 people have already bled to death since the Ebola virus surfaced
in northern Uganda two weeks ago. But American government scientists believe
that a vaccine is just a few years away.
Ebola expert Gary Nabel of the US National Institutes of Health has tested a
DNA vaccine in primates, which he says protects them from the deadly infection.
And while he is reluctant to comment on his vaccine before the research is
published, other researchers are also making progress.
Vaccines usually work by stimulating the production of antibodies in response
to viral material. But people exposed to Ebola only make a very small number of
neutralising antibodies, so straightforward vaccines made from the killed virus
won鈥檛 work. Failure to identify the natural animal reservoir鈥攑ossibly a
rodent or bat鈥攚here the virus lurks between outbreaks makes the
scientists鈥� task more difficult.
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Earlier this year, however, researchers at the US Army Medical Research
Institute of Infectious Diseases at Fort Detrick in Maryland developed a vaccine
containing antibodies pooled from hybrid cancer-immune cells created in the
laboratory. This protected mice from the virus
(快猫短视频, 11 March, p 19).
And this month at a meeting in Sweden, Fort Detrick researchers presented
evidence of another vaccine that protected primates by stimulating the
production of killer T cells as well as antibodies.
鈥淭he science is moving forwards at a good pace, which we could not have said
three years ago,鈥� Nabel says. 鈥淚 think it鈥檚 possible that in a few years we will
have either a vaccine or a cure.鈥�
The gruesome events in Uganda show why a vaccine is needed so urgently.
Ebola, a type of filovirus, generally kills between 50 and 90 per cent of the
people it infects. Victims suffer massive internal haemorrhaging and may die in
a matter of days, with blood pouring from all orifices. The virus is easily
spread by contact with bodily fluids.
Ray Arthur, the World Health Organization medical officer in charge of
containing Ebola, said a vaccine would be targeted at medical staff dealing with
outbreaks.
As 快猫短视频 went to press, the number of cases had hit 160 and
was still rising. 鈥淚t鈥檚 going to get worse before it gets better,鈥� a WHO
spokesman says. Some comfort came from the news that the strain of Ebola
afflicting Uganda has been identified as the Sudan strain. This has a mortality
rate of around 60 per cent, compared to the 90 per cent death rate of the Zaire
strain that killed over 242 people in Kikwit five years ago.
But doctors might have another weapon in the fight against Ebola. The WHO,
and scientists from NASA, believe a rare climate pattern precedes outbreaks of
the disease. If satellite data confirms the theory, public health officials
could send vaccine to high-risk areas before the disease surfaces, the
researchers say.