AIDS vaccine focus shifts after disappointments

[Guest guest]

AIDS vaccine focus shifts after disappointments

By Quinn Mon Oct 13, 9:31 AM ET

WASHINGTON (Reuters) - A global AIDS vaccine conference this week

will seek fresh strategies against the HIV virus, with experts

weighing the value of basic laboratory research against large-scale

human clinical trials after a string of disappointments.

Approaches focusing on " neutralizing antibodies " that would allow the

human immune system to block infection completely, are likely to take

precedence over existing models that seek to manage infection after

it occurs, experts said.

" There's a real redirection and rethinking, " said Lynn , co-

chair of a world AIDS vaccine conference that starts in Cape Town,

South Africa, on Monday.

" Fundamentally we don't understand enough about the human immune

system and we don't know how the immune system deals with HIV. "

The conference -- a gathering of many of the top names in HIV

research -- follows a year that saw scientists drop plans for

widespread human testing of the two most promising vaccine prototypes

due to safety concerns.

The AIDS virus infects an estimated 33 million people globally and

has killed 25 million since it was identified in the 1980s. Cocktails

of drugs can control the virus but there is no cure.

The two stalled vaccines, one developed by drug giant Merck and the

other by U.S. government researchers, both aimed to fight AIDS by

encouraging so-called cell-mediated immunity, jump-starting T-cells

to tackle the virus and stop or slow the progress of HIV-related

disease.

But early results from a large human trial of the Merck product were

discouraging and data showed the vaccine may have left some people

more prone to HIV infection -- halting the tests and prompting some

scientists to reconsider the model.

" A REAL SWING BACK "

, the head of the AIDS unit at South Africa's National

Institute for Communicable Diseases, said the focus was now on

another approach to fighting HIV: lab work to discover how to help

the body produce antibodies to prevent infection altogether.

" Neutralizing antibodies are a major component of almost all other

vaccines, " said. " I think there is going to be a real swing

back to thinking about them. "

The International AIDS Vaccine Initiative last month announced it was

launching a $30 million joint venture research lab in California

dedicated to accelerating work on neutralizing antibodies.

The renewed focus on lab work has left some scientists and advocates

worried that human clinical trials of vaccine candidates may suffer

as funding shifts toward basic research.

But said limited human trials of new vaccine concepts would

have to continue, arguing against some researchers who say the money

would be better spent on animal research or improved AIDS drugs.

" There's no guarantee that basic researchers are going to come up

with the answers, " said.

" But I feel quite strongly that clinical research should continue. If

people are willing to participate in this because there is a hope

that we may develop a vaccine then that's what I think we should be

doing. "

The four-day Cape Town conference will give scientists, funders and

community advocates a chance to assess the direction of AIDS vaccine

research, which in 2007 accounted for about $960 million in

investment -- the bulk of it from the public sector.

It will also give scientists a chance to delve more deeply into the

results of the failed Merck vaccine trial.

Conference reports may explain how the vaccine -- made by sticking

genetic pieces of HIV to a cold virus -- made some participants more

likely to contract the AIDS virus, as well as hints that certain

volunteers did see benefits from the Merck vaccine, keeping interest

in the T-cell model alive.

said this year's disappointments could not be allowed to

derail the pace of research.

" It's an iterative process. You don't just, boom, come up with a

vaccine, " she said. " We have to accept that maybe it's not going to

be possible. But until we know that, we have to keep trying. "

(Editing by Will Dunham and O'Callaghan)

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