The journey to find the HIV vaccine has been a long one. Why?

We asked a few of today's leading HIV/AIDS specialists about the scientific challenges of working with the HIV virus and development of a safe and effective vaccine.

Not only does the human-specific HIV attack the very system (the immune system) that typically helps to ward off viruses, but it constantly changes, adapting to the body's antibodies. This is called adaptive immunity.

Some other unique challenges in working with HIV include:

  • Most vaccines protect against disease, not infection. However, the HIV infection does not result in AIDS (the disease) for an extended period of time.
  • A partial (or dead) HIV virus loses its potency, and thus cannot be used for a vaccine. Yet, using a live virus is too dangerous. Therefore, scientists must develop synthetic viruses that model the structure and ideally elicit similar immune responses as the actual virus. Synthetics, while more complex, are significantly safer, and are commonly used in other vaccines like the flu vaccine.
  • While most vaccines guard against infection contracted primarily through gastrointestinal or respiratory tracts (the flu, for example), a great majority of HIV infection occurs through the genital tract, which responds only weakly to infection.
  • HIV may be encountered by a single individual multiple times in various and diverse forms or strains; this is called biodiversity. Therefore, successful vaccine concepts must ward off many different viruses at once.
  • Typical vaccines mimic natural immunity seen in patients who have recovered from infection, but there are no recovered HIV/AIDS patients.

Come back later this week as we take a look at what it takes to develop an HIV vaccine and the progress that has been made to date.

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Lindsey R. Baden , M.D., is Director of Infectious Diseases, Dana-Farber Cancer Institute; Director of Clinical Research, Division Infectious Diseases, Brigham and Women's Hospital; and Assistant Professor of Medicine at Harvard Medical School.

Dan H. Barouch, M.D., Ph.D. is the Chief of the Division of Vaccine Research, Department of Medicine, Beth Israel Deaconess Medical Center; and an Associate Professor of Medicine at Harvard Medical School.

Ken Mayer M.D., is the Medical Research Director and co-chair of the Fenway Institute at Fenway Health.

This is Part One in the four-part blog series Preventing the Unpreventable: The Search for the HIV Vaccine written by Devon Dickau, who interned at NOVA in the spring of 2011 before graduating from the Harvard Graduate School of Education's program in Technology, Innovation and Education.

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