WHITEHOUSE STATION, N.J. (AP) _ Pharmaceutical giant Merck & Co. said Friday that it has started the first global human tests of an experimental AIDS vaccine, working with the Seattle-based HIV Vaccine Trials Network.

The experiment, which will include about 435 adult volunteers not infected with the HIV virus, is meant to determine if the vaccine candidate is safe, has tolerable side effects and is practical to administer in different parts of the world. Researchers will also determine whether the vaccine stimulates an immune response in people.

The study is being conducted in 18 cities in North America, South America, the Caribbean, southern Africa and Southeast Asia. Using such diverse testing sites is important because different strains of the HIV virus circulate in different regions. The vaccine is made from a modified cold virus and does not contain any live HIV virus, so it cannot cause HIV infection.

Merck currently is running tests of other potential HIV vaccines on people, including an experiment announced earlier this week in which is testing combination of one of its experimental AIDS vaccines and another from Aventis Pasteur. Whitehouse Station-based Merck began doing human tests of experimental HIV vaccines in late 1999.

The vaccine trials network is supported by the National Institutes of the Health.

Merck & Co. shares were down 79 cents to close at $52.29 on the New York Stock Exchange.

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On the Net:

http://www.merck.com

http://www.hvtn.org