The annual international conference on AIDS that ended in Vancouver last
week turned out to be unlike any of its ten predecessors. Of course, scientists,
doctors, sociologists, politicians and public health officials turned up in
their usual tens of thousands and AIDS activists staged their predictable
protests. This year they dumped a red dye looking unpleasantly like blood over
several of the conference organisers.
But the big difference from previous meetings was that many scientists left
Vancouver feeling optimistic about winning the war against HIV.
Usually the conference merely deepens the gloom over the enormity of the
problem and the lack of definite scientific progress. Hope now comes from new
studies which report the near-elimination of HIV from the blood of people
treated with cocktails of drugs that block replication of the virus.
The usual first ingredient is the well-known drug zidovudine (AZT), which
interferes with the initial step in replication when the virus makes a DNA copy
of itself, plus other AZT-like drugs. Added to that are one or more protease
inhibitors which knock out the enzyme needed by HIV to create the proteins
essential for multiplication. Other cocktails are also under test, including
mixtures of several different protease inhibitors.
The protease inhibitors caught the attention of the world’s media during the
conference but they are no magical solution. HIV can mutate and become resistant
to every one of the new-generation protease inhibitors, just as it can to every
other anti-HIV drug. The trick is in creating the right cocktail: in theory the
virus should find it much harder to amass the mutations needed to develop
resistance to all the drugs in the cocktail at the same time. And while the
drugs remain effective they should keep viral replication—and hence the
emergence of new mutations—close to zero (see “HIV’s war of attrition”,
New Scientist, 13 May 1995).
To judge by the results reported at the conference, the cocktails work in
practice as well as in theory. One mixture of protease inhibitors reduced virus
levels in the blood of people with HIV to an undetectable level. Other studies
using different cocktails also achieved huge reductions in the level of the
Even though there are genuine grounds for optimism, there are still huge
uncertainties. It is still unknown whether reducing the amount of virus in the
blood will translate into a long-term improvement in a patient’s health, let
alone a cure. (New Scientist will report the latest progress in its
issue of 3 August). It is quite possible that the virus will hide in the brain,
behind the blood-brain barrier where drugs cannot easily pass, and re-emerge
later when people have stopped taking the drugs. Even if the virus is completely
eliminated from the body, it would still seem unlikely that the damage already
done to the immune systems of people with AIDS would repair itself. Patients may
still be at risk from opportunistic infections.
Assuming the drugs cocktail is effective in the long term, many problems
still remain. It is possible there will be serious side effects. And the drugs
are very expensive, currently costing around £10 000 for one year’s
supply. With 1 in 300 Americans now HIV positive, even the richest nation in the
world will have difficulty providing treatment for all.
Elsewhere, prospects are truly bleak: 90 per cent of all people with HIV live
in the developing world. They cannot possibly afford the new drugs. And HIV
continues to spread to new places where expensive drugs treatments are not going
to be easily available. Data revealed at the Vancouver conference show that HIV
is now spreading at enormous speed in the nations of the former Soviet Union
(see p 6) and across India.
A vaccine against HIV remains the top priority in the long term.
Unfortunately, the conference showed that progress remains very slow and
investment small. Big pharmaceuticals companies are not willing to put their
efforts into vaccine development when the major market is likely to be in the
AIDS is, of course, a preventable disease that can be easily and cheaply
avoided by changing behaviour. For many reasons, the efforts to prevent the
spread of HIV—through education and vaccine development or something as
simple as the development of improved condoms—still don’t match those to
cure it. But that is hardly surprising: it is the familiar and depressing
conclusion that has dominated the ending of so many of the past international
conferences on AIDS. This time, at least, there was some good news as well.