WASHINGTON (AP) _ The Supreme Court, rejecting an appeal by two generic drug manufacturers, today let stand a ruling that said Burroughs Wellcome Co. is entitled to five patents for AZT, the primary drug for treating AIDS.

The court, without comment, turned away the argument that Burroughs should not receive exclusive patents because some testing was done at the National Institutes of Health.

AZT was developed in the 1960s as a possible anti-cancer drug, but was not found promising for that use.

After acquired immune deficiency syndrome was identified during the 1980s, the National Institutes of Health asked drug laboratories to submit for testing any compounds that might be effective in AIDS treatment.

Burroughs submitted AZT along with other compounds. After the drug was found to be effective against the human immunodeficiency virus that causes AIDS, six patents were awarded to Burroughs, based in Research Triangle Park, N.C.

AZT went on the market in 1987.

Barr Laboratories, based in Pomona, N.Y., and Novopharm, based in Ontario, each sought federal permission to sell generic versions of AZT. Burroughs sued both companies, alleging patent infringement.

Barr contended that two NIH scientists who tested AZT should be added to the patents as co-inventors. If that were done, Barr said, it could manufacture a generic form of AZT because NIH gave it non-exclusive rights to do so.

Novopharm contended the Burroughs patents were invalid because the NIH scientists were not named as co-inventors.

A federal judge in North Carolina upheld the patents in 1993, saying Burroughs showed it had a ``definite and permanent idea'' of how AZT would be used to fight AIDS. The judge said Burroughs need not show it had a reasonable belief before the NIH testing that AZT would work.

The U.S. Court of Appeals for the Federal Circuit upheld the ruling for five patents and sent the sixth back for trial.

In the appeals acted on today, lawyers for Barr and Novopharm said an invention must be shown to work before it becomes eligible for a patent, and thus the NIH scientists are entitled to share the patent.

Burroughs' lawyers said requiring companies to share patents with other scientists who test an idea would discourage cooperative research.

The cases are Barr Laboratories vs. Burroughs Wellcome, 94-1527, and Novopharm vs. Burroughs Wellcome, 94-1531.