Why is developing an AIDS vaccine so difficult?

Over the years, scientists have developed a myriad of vaccines, some of which have eradicated the world’s most dangerous diseases. So why is an AIDS vaccine still so elusive? New research by OHSU’s Louis Picker, M.D., published online in Nature Medicine, explains. Dr. Picker likens our search for an AIDS vaccine to the tale of ‘Goldilocks and the Three Bears’: “The field was looking for a vaccine that was ‘not too hot,’ or ‘not too cold,’ but ‘just right.’ The problem was that it appears that weakening a virus to the level that is ‘just right’ is impossible.”

In most vaccines, a weakened or dead form of a virus is used to stimulate a person’s immune response in the blood, thereby preventing them from developing a full-blown case of the disease if they are later exposed. With AIDS, this approach is not effective. Dr. Picker’s research demonstrates that the anti-viral T cells in lymph nodes (not the blood) determine the long-term efficacy of a vaccine. Using another virus like cytomegalovirus, or CMV, that sticks around in the body and acts as a transport for the weakened virus may help keep the vaccine in the body so that it remains effective.

Read the full OHSU News Release.

This research was funded by the Bill and Melinda Gates Foundation, the International AIDS Vaccine Initiative, and the National Institutes of Health.