CAPE TOWN, South Africa (AP) -- The global economic turmoil is likely to take its toll on AIDS research funding and add to the problems plaguing the search for a vaccine against the virus, scientists warned Tuesday.

Anthony Fauci, director of the U.S. National Institutes of Allergy and Infectious Diseases, said it was impossible to predict whether scientists would ever be able to develop an effective vaccine, as they have for other killers such as smallpox and measles.

"Will there be a guarantee that we will get a vaccine in the classical sense? Realistically you can't say that," Fauci said. "But that doesn't mean we are going to give up trying."

Nine hundred experts are attending the international AIDS vaccine conference in Cape Town, at the epicenter of an epidemic that has infected an estimated 33 million people, of whom 5.5 million are in South Africa.

The economic downturn has added to the gloom among experts deeply frustrated by research setbacks. A recent trial showed that one potential vaccine not only failed to prevent infection but appeared to increase the risk of contracting the virus.

Now there is added concern that philanthropic organizations, like the Bill and Melinda Gates Foundation, who have become major players in health and development projects may cut back on funding.

"It's not good news for research in general and vaccine research in particular," Alan Bernstein, head of the Global HIV Vaccine Enterprise, told the Associated Press.

"It has been a very turbulent year."

Fauci said the National Institutes for Health total AIDS budget this year was US$1.5 billion of which US$491 million was dedicated to vaccine research. This was up from US$703 million in 1998, with US$115 million for the vaccine, and US$223 million in 1988, with 22 million allocated to developing a vaccine in an era when scientists were still optimistic about success.

Fauci said while he did not expect the U.S. government to cut its spending on AIDS, "the increases in the budget that we had hoped for will not be forthcoming."

And he said he feared the financial downturn would impact on the "enthusiasm and ability of philanthropic research and development."

Fauci rejected criticism from "naysayers" who argue that too much taxpayer money has been spent on the vaccine. "If you can prevent infection, you are preventing the need for a lifetime of expensive drugs," he said, referring to antiretroviral therapy that can prolong people's lives many years. "If you look historicially, vaccines have been the most cost effective health interventions in history and continue to be so." And he said it would be wrong to divert funding from vaccine research -- as some prominent scientists have argued -- into male circumcision which can reduce HIV transmission by up to 60 percent. "We tend not to think of either or," he said. Dramatic results from trials into male circumcision prompted the United Nations last year to recommend that government embrace it as part of their AIDS prevention armory. But African countries that are keen to embark on mass male circumcision complain they lack the resources and the medical expertise needed. Funding programs from international donors are still in their infancy.

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