CAPE TOWN, South Africa -- South African scientists said Thursday they will begin manufacturing, and testing on humans, three new vaccines intended to protect against the AIDS virus.

The vaccines showed great potential in laboratory tests on mice and primates, said Anna-Lise Williamson, associate professor at the University of Cape Town's Institute of Infectious Diseases and Molecular Medicine.

Small-scale human trials could begin as early as next year, said Dr. Tim Tucker, director of the South African AIDS Vaccine Initiative.

UNAIDS, the United Nations agency on AIDS, last year estimated that 40 million people worldwide were HIV-positive and the development of a vaccine was considered imperative to stop the epidemic's spread.

More than a dozen candidate vaccines are at various stages of testing worldwide.

Trials under way

Human trials are under way in the United States, Brazil, Britain, Haiti, India, Kenya, Peru, South Africa and Thailand.

The vaccines developed by the University of Cape Town will be manufactured and tested in the United States and Britain. They will be produced using genetic material from the strain of HIV most commonly found in Southern Africa.

The scientists will insert harmless pieces of the HIV virus into human cells in hopes of stimulating the production of antibodies that will provide immunity.

The South African AIDS Vaccine Initiative will contribute $1 million toward producing and testing the vaccines, while the U.S. National Institute of Health will contribute about $2 million.

About 4.7 million South Africans -- or one in nine -- are HIV positive, more people than any country in the world.

The South African AIDS Vaccine Initiative was established by the government three years ago and charged with developing an affordable, effective and locally relevant HIV vaccine.