A model VRC34.01 antibody (green and yellow) bound to the fusion peptide (red) in a peak on the surface of HIV (gray). Credit: NIAID
A team led by scientists at the National Institutes of Health (NIH) reported a trifecta investigation. They have discovered a new point of vulnerability of HIV to a vaccine with a broadly neutralizing antibody that binds to that target site and how the antibody prevents the virus from infecting a cell. The study was conducted by scientists at the Vaccine Research Center (VRC) of the National Institute of Allergy and Infectious Diseases, part of NIH.
The new target is a part of HIV called a fusion peptide, an eight-amino acid chain that helps the virus fuse into a cell to infect it. The fusion peptide has a much simpler structure than other surface spots of the virus that the HIV vaccine scientists have studied over time.
Scientists first examined the blood of HIV-infected people to explore their ability to prevent the virus from infecting other cells. The blood was able to neutralize HIV but not at the target site at any of the points that were known to attach to broadly neutralizing antibodies against HIV (bnAbs).
The researchers isolated a powerful bnAb in the blood sample they named VRC34.01 and found that it binds to the fusion peptide and to a sugar molecule. The scientists then crystallized the antibody while it was linked to the virus. This allowed them to characterize in detail at the atomic level how VRC34.01 attributes to HIV and revealed that the antibody prevents the virus from infecting a cell by binding to a key molecule of the cell surface.
Scientists also report that it is not uncommon for the immune system to try to stop HIV in the process of infecting a cell by attacking the fusion peptide. When they screen the blood of 24 HIV-infected volunteers, they found that blood samples from ten people showed binding sites similar to VRC34.01.
Researchers are working to create a vaccine designed to motivate antibodies similar to the VRC34.01 antibody to adopt this type of behavior.
The study was published in the journal Science.
12 May 2016 with Carlos Mota information