Vaccines, microbicides and HIV prevention

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Seth BerkleyWASHINGTON, Oct. 30 (UPI) -- How close are the scientific and medical communities to marketing a vaccine for HIV and AIDS?

Over the past 25 years a number of vaccines have been researched, but only one candidate has gone through full testing, only to be ineffective, said Seth Berkley, president and CEO of the International AIDS Vaccine Initiative.

Currently about 30 other trials are being conducted in 25 countries. One promising candidate, from Merck, consists of a common cold virus in which pieces of the virus have been replaced with HIV. Preliminary efficacy results are due in 2008, with final data in 2010.

A key concern is whether it would be effective in people who have been exposed to those strains of the cold virus, Berkley said. In the developing world, about 80 percent of the population has been exposed, he noted.

Even with constant research and clinical trials, researchers are still missing a key piece of the puzzle: None of the current vaccine candidates produce broadly neutralizing antibodies, said Candace Pert, former National Institutes of Health researcher and founder of R.A.P.I.D. Pharmaceuticals Inc.

There are several strategies that address the problem but do not completely solve it. To make a highly effective vaccine, scientists need to identify an immunogen with the correct sequence of peptides to create those antibodies.

Despite the complexities, advocates say a vaccine will eventually be developed. All experimental evidence points to the possibility of a vaccine, Berkley said.

In the meantime, preventing the spread of HIV remains crucial. One promising compound is a topical microbicide that might be available in the next five years. Microbicides are keys to prevention in women from developing countries, said Zeda Rosenberg, chief executive officer of the International Partnership for Microbicides.

One plus for a microbicide: It could be used much like birth control -- women can apply it in situations when their partner may not be willing to take responsibility, she said.

Final clinical data for Carraguard, a microbicide gel, is expected to be available by the middle of next year, Rosenberg said.

The vaccine initiative's latest report calls for taking vaccines that look promising and testing them on people; going back and working more aggressively on rational vaccine design; and changing the models for each trial by first going into high-incidence areas to quickly get answers on efficacy rather than conducting large, expensive trials.

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