The fight against AIDS remains a long and hard journey for experts around the world.

According to a top US AIDS scientist, research is about to go back to laboratory basics, following setbacks in the search for an elusive vaccine.

Dr Anthony S Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), and his colleagues announced the turnabout in an article in the magazine Science.

Fauci says that his federally funded institute, which distributes about 80 percent of the money spent worldwide on vaccine research, will "rev up the burners" to tackle the decades-old puzzle of how to create antibodies against the disease without causing an actual infection.

That means less money will be spent on human trials of vaccines that might work in less conventional ways, a hope that once buoyed researchers' efforts, only to later disappoint.

More use will be made of animals in research. "The emphasis right now will be on improving the non-human primate model," Fauci says. "What is the best animal model that we can perfect? Why does the body not make adequate neutralizing antibodies in response to natural infections?"

The shift in focus follows intense discussion within the HIV/AIDS research community, and the announcement comes just a week after Fauci decided to cancel a large human trial of the institute's own PAVE vaccine, which is similar to one privately produced and tested by Merck pharmaceuticals, and later dropped, in September 2007.

The Merck vaccine was found to be ineffective and in fact appeared to have inadvertently increased the HIV infection rate. Trials were dropped midway.