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Traditional vaccine methods have been unsuccessful in preventing infection by HIV, the virus that causes AIDS. New techniques are being studied to boost antibodies or other parts of the immune system. But researchers are also working on a method to keep the immune system constantly on guard against HIV. There are two traditional methods for creating a vaccine. One uses a weakened or attenuated version of a live virus to generate an immune response. The other uses a dead virus. Both methods are proven safe and effective, except when it comes to HIV. Vaccine candidates using these methods simply have not been successful in people when it comes to the AIDS virus. “HIV has been a very difficult target for a vaccine for a variety of reasons. It’s designed to evade the immune response by evolution,” said Dr. Louis Picker, associate director of Oregon Health and Science University. While attempts to make an HIV vaccine from a dead virus have failed, Picker said, using a weakened virus holds clues and possibilities when used in primates. “The live attenuated approach actually was shown to work 20 years ago. But the problem with it was the live attenuated vaccines that actually worked were actually still pathogenic. So they weren’t safe and they could not be moved into humans. This was demonstrated in the non-human primate models – monkey model of AIDS using the virus SIV,” he said. SIV stands for simian immunodeficiency virus. | 
