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Human trials of HIV vaccine to begin
By Perla Astudillo
19 August 1998
At the recent 12th World AIDS conference in Geneva, researchers
announced that the US Food and Drug Administration had granted
approval for the first Phase 3 or human trials of a vaccine against
Human Immunodeficiency Virus (HIV). The vaccine, known as AIDSVAX,
is to be tested on 5,000 male and female volunteers in at least
40 sites across the US. The trials will also extend to 2,500 volunteers
in 16 clinics throughout Thailand.
Despite years of research, scientists have faced great difficulties
in developing a safe and effective vaccine against HIV. The virus
undergoes rapid mutation and, as a result, a vaccine may provide
some protection against only one of the different HIV varieties.
The particular characteristics of HIV have compelled researchers
to turn to a number of new techniques in developing a vaccine.
Unlike other viruses, the body's natural immune response does
not destroy HIV, and thus, a vaccine cannot simply rely on stimulating
or priming the body's own defences.
Furthermore, researchers have been very cautious about using
whole HIV viruses, whether in live, dead or inactivated forms,
in preparing a vaccine. The technique, used to combat other viral
diseases, poses dangers if the vaccine causes HIV infection.
The start of Phase 3 trials for AIDSVAX is, therefore, a significant
step forward. Known as a "subunit" or "recombinant"
vaccine, its development has involved the use of advanced biotechnology
methods to manipulate the genetic structure of the HIV virus.
Many of the recombinant HIV vaccines currently under investigation
focus on a number of particular proteins found on the outer surface
of the virus. One such protein gp120 (or glycoprotein 120) is
particularly significant as it is part of the means by which the
virus attaches itself to the body's immune system cells and infects
them.
Other vaccine research targeting gp120 has run into difficulties
as the protein differs with the particular HIV variety. AIDSVAX,
however, has been created by taking gp120 from the surface of
two different types of HIV--one an already tested laboratory strain,
and a second from one of the currently circulating virus strains.
AIDSVAX B/B uses a type found in the US, and AIDSVAX B/E a type
found in Thailand. The vaccine is the first to be designed to
target specific HIV strains in different parts of the world.
By using two gp120 types, researchers hope the vaccine will
stimulate an immune response in a significant number of people
involved in the trials. AIDSVAX has been developed by Genentech,
a US company that has invested some $20 million on the vaccine
and the preparations for human trials.
Scientists are doubtful that AIDSVAX will provide a quick breakthrough
in the control and prevention of HIV. Researchers state that the
vaccine will only help inhibit the spread of the infection and
assist in reducing the incidence of full-blown AIDS.
The theme of the World AIDS Conference was "Bridging the
Ever Widening Gap"--an attempt to address the huge gap in
the treatment available to AIDS sufferers in rich and poor countries.
Of the 30.6 million individuals currently infected with HIV worldwide,
over two-thirds live in Sub-Saharan Africa where there are few
or no resources available for care or prevention.
A revealing discussion broke out on the implications of vaccine
testing in so-called Third World countries. Some of the participants
asked whether companies like Glaxo and Genentech were prepared
to cover the full costs of treatment, including hospital care
and anti-AIDS drugs, if volunteers in the trials become infected.
According to a report in the Science journal, "The
majority of the participants at the Geneva meeting agreed with
the practical argument that people who become infected during
an AIDS vaccine trial should be offered the `highest attainable'
treatment in their locale that can be sustained after the trial
ends."
In other words, the level of medical care will vary significantly
depending on whether the trial participant lives in Bangkok or
New York. As the article pointed out, "neither the company
nor the cash-strapped Thai government plans to give cutting-edge
treatments to people who become infected."
The impossible barriers facing those at risk of HIV in backward
countries was further highlighted at the conclusion of the conference.
Five major pharmaceutical companies, including Roche, Bristol-Myers
Squibb and Glaxo Wellcome, agreed to start a $4 million pilot
program to provide the anti-AIDS drug AZT to 30,000 pregnant women
in 11 countries at a 60 to 75 percent discount.
But the cost of anti-AIDS treatment is estimated to be around
$20,000 a year for each patient. The paltry $4 million discount
given by the drug companies amounts to a year's anti-retroviral
treatment for just 50 people. Even at the discounted price, the
companies--which rake in hundreds of millions of dollars a year--will
make a profit.
Physician Elly Katabira of the Mulago Hospital in Kampala,
Uganda commented: "Even if the price [for combination therapy]
was only $200 per month, which is peanuts in Western countries,
this is more than many Africans earn in their lifetime."
See Also:
HIV/AIDS
epidemic ravages Africa
[25 June 1998]
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