Health activists Tuesday assailed the National Institutes of Health for asking pharmaceutical companies to bid for the exclusive license to make a promising AIDS drug developed by government scientists. In a letter to the National Institute of Allergy and Infectious Diseases,a branch of the NIH the American Public Health Association joined with Public Citizen Health Research Group and the National Gay and Lesbian Task Force to criticize any such licensing agreement. CD4-pseudomonas exotoxin is a genetically engineered drug that in a test tube has been shown to target and destroy cells infected by the AIDS virus. It was createdby NIAID scientists, and this month the NIH asked interested companies to submitbids for an exclusive license.The license would contract the winning company to guide the drug through the human tests required by the Food and Drug Administration and would grant sole marketing rights if the drug then gained FDA approval. The opponents who wrote in protest argued that the CD4-PE bid proposal lacks controls on the eventual price of the drug or the speed of development.