Hurdles Remain for Preventative HIV Vaccine

Researchers seek to induce broadly neutralizing antibodies to block numerous HIV variants.

Scientists are taking a complex, creative, and elegant approach unparalleled in other research efforts to create vaccines that induce broadly neutralizing antibodies to block a wide range of HIV variants.

Thus far, the only large clinical study for an HIV vaccine that showed promise was conducted in Thailand in 2009. Although the vaccine produced a modest 31% reduction in infection, researchers are working to improve upon these results.

In commentary from Anthony S. Fauci, MD, director of the National Institute of Allergy and Infectious Diseases, he explained that B cells typically produce neutralizing antibodies (NAbs) to most viruses within only days or weeks of infection.

Since the NAbs allow infected individuals to clear the viral strain and have lifelong immunity, the principle is often used to create most viral vaccines. However, individuals who are infected with HIV do not readily produce Nabs, but when they do, they aren’t produced in a sufficient amount of time to clear or control the infection. This created significant challenges in creating a preventive HIV vaccine.

To overcome these challenges, researchers used methods and technologies rarely seen in other branches of vaccine research, such as rigorous analyses of B cell repertoire and its evolution, and sophisticated structural biological techniques that analyze the precise molecular conformation of the viral components and their interaction with NAbs.

Fauci noted that if the efforts are successful, it will be remembered as the most complex and elegant approach toward the development of a vaccine in history. Conversely, if the efforts are unsuccessful, they can still provide comprehensive evidence that it would be unlikely a vaccine will be able to induce the broadly neutralizing antibodies.