AIDS: Highlights from the Conference on Advances in AIDS Vaccine Development: 1996 at the National Institutes of Health (NIH) on February 11-15, 1996, are described. The need for cooperation from both government and industry in the search for new treatments and a vaccine for HIV was emphasized. Scientists discussed the development of a genetic tree that may help organize the genetically diverse mix of strains worldwide and concluded that recombination will continue to be an important variable in AIDS research. In an unrelated talk, researchers described a new resting cell assay, a test used to measure virus neutralization. Investigators are hopeful that the new test will lead to advances in vaccine development. Investigators reported on the modified vaccine in development for the protection of macaque monkeys against simian immunodeficiency virus (SIV). The monkeys were inoculated with a nef-deleted SIV vector vaccine that was inserted with the gene for gamma interferon, and have remained healthy for 28 weeks. Discussion at the meeting also centered around the progress of investigations for genetic, or DNA, vaccines. Researchers at three separate institutions described their unique approaches to the development of a vaccine that will not use live virus. Also, investigators at the St. Louis University Health Sciences Center AIDS Vaccine Evaluation Group (AVEG) site presented an overview of HIV vaccines available for expanded clinical trials. Since 1988, AVEG has tested more than 15 vaccines in 25 trials. Finally, presenters at the meeting discussed the preparations underway for the HIV prevention trials that will take place in eight sites across the United States.