Current estimates put the number of people affected by AIDS
worldwide at 30 million and growing. Affluent nations are now using
effective drug therapies but their cost makes them inaccessible to
affected people in the developing world. An AIDS vaccine would be
less expensive, particularly if only a few doses were required to
give life-long protection against infection. The European Vaccine
Against AIDS programme is playing a unique role in encouraging pan-European
research efforts. It provides research tools such as live virus, cell
lines and proteins that individual groups would otherwise be unable
to access. It is also proactive, initiating and encouraging new collaborative
projects throughout the EU and facilitating the exchange of skills
and knowledge through its regular International Workshops.
Many experts think that a combination
vaccine might be necessary.
Developing a vaccine against the Human Immunodeficiency
Virus (HIV), which causes Acquired Immune Deficiency Syndrome (AIDS),
has proved exceptionally tricky. Many viral diseases can be prevented
very effectively by vaccination - measles, mumps, rubella, smallpox
and polio are just a handful of examples. But, after almost 20 years
of intensive research, an AIDS vaccine remains just out of reach.
The virus infection itself does provoke an immune response in the
body, but attacks and kills cells of the immune system. The virus
also changes its appearance very regularly, outwitting the body's
In Europe the number of new cases of AIDS
has declined over the last five years because of preventive
Vaccine versus drugs
The roots of EVA are in the UK's AIDS Reagent Project, which ran throughout
the 1980s. This was a major research effort funded by the British
Medical Research Council to establish a reagent supply programme to
provide key research materials to workers in the field. "Our aim was
to supply high quality materials - cell lines, live virus, peptides
and so on, that researchers could use to progress their work into
potential AIDS vaccines more quickly than if they had had to make
those materials themselves," explains Harvey Holmes.
A decade ago, many pharmaceutical companies throughout the world
were placing more or less equal emphasis on drug development and
vaccine research. In the intervening years, this balance has changed
and commercial drug companies have diverted most of their resources
towards the successful combined therapies. Today, AIDS vaccine research
has become largely government funded. The European Union, in particular,
is currently providing research grants to many projects. One of
the largest is EVA, the European Vaccine Against AIDS programme,
co-ordinated by Dr Harvey Holmes and based at the National Institute
for Biological Standards and Control (UK).
Moving into Europe
With the EU support, this service was extended to the whole of Europe.
The EVA project, which began in 1993, now involves participants
from 12 EU countries. The bank of materials supplied is being added
to all the time. Most are made on site at NIBSC, the EVA centralised
facility, but some biotech companies make specialised products under
contract. Although EVA will supply reagents on demand, and will
even make new reagents to order if the research group asking for
them can make a good case, the project has also a proactive role.
"One of our major objectives is to bring European AIDS vaccine researchers
together. Collaborative projects are good for all sorts of reasons
- different labs can share resources, results are better, the researchers
learn new techniques from each other - and they make the use of
the reagents we produce much more effective," comments Harvey Holmes.
EVA provides the necessary reagents and holds regular workshops
to help researchers:
- Develop and test live but attenuated (disabled) virus vaccines.
- Carry out immunisation studies with short pieces of naked nucleic
acid from HIV. Tests in animals have shown that this works surprisingly
- Investigate the possibility of blocking receptors for HIV in
body cells. The recent discovery of the importance of chemokine
receptors, the second main receptors for HIV, has opened up lots
of new possibilities in this area.
- Put the genes for key HIV envelope proteins into a disabled
vaccinia virus. This is a large harmless virus that can multiply
to a very limited extent in the body. It is used widely to give
vaccines a 'piggy-back' to get them into the body. Vaccinia produces
enough of the HIV proteins to give a good immune response.
No one is sure which approach will meet with the ultimate success
and many experts think that a combination vaccine might be necessary.
"We could end up with a vaccine that consists of a naked DNA component,
followed by an injection of vaccinia virus containing HIV proteins,
all topped off with an immunisation with purified HIV proteins.
Such a multi-faceted vaccine might give good enough immunity to
keep the number of boosters required fairly low, once a year at
the most," says Holmes.
But there is a long way to go yet. More animal studies are needed
and any potential vaccine must be tested exhaustively to make sure
it is safe before human trials begin. There are still uncertainties,
but AIDS experts are optimistic that an AIDS vaccine is possible,
and one thing at least seems definite: the reagents and materials
provided by EVA will have played a major part in its development.