HIV has remained an elusive disease for scientists to design an effective vaccine, due to the pathogen’s shape-shifting tendencies in the body. A novel drug candidate against HIV has been created by a joint team led by researchers at The Scripps Research Institute in Jupiter, Flordia. The scientists consider it to be so potent and effective that the protein could be used to form the basis of a vaccine that would have the ability to inactivates virtually all strains of the virus.

The results of the study, which are published in the journal Nature, demonstrate how the new drug candidate successfully blocked every known strain of HIV-1, HIV-2 and SIV (simian immunodeficiency virus), including the variants that, historically, are most difficult to block.

Described at “the broadest and most potent entry inhibitor so far” by Michael Farzan, a Scripps Research Institute professor who led the effort, this genetically engineered protein can compete with the many strains of rapidly mutating HIV that remain resistant to the currently identified super antibodies. These broadly characterized antibodies work on multiple strains of the human immunodeficiency virus, but fail long term. “Unlike antibodies, which fail to neutralize a large fraction of HIV-1 strains,” continues Farzan, “our protein has been effective against all strains tested, raising the possibility it could offer an effective HIV vaccine alternative.” The new drug was also found to protect against doses of the virus higher than those that normally occur in human transmission for at least 8 months after injection.

This project is the culmination of more than a decade’s work on understanding the biochemistry of HIV entry into cells and follows research done by The Scripps Research Institute on co-receptor CCR5, the first attachment point on a human cell by which HIV  binds in order to penetrate the cell. When a cell is infected by HIV, it inserts its own single-stranded RNA into the host cell. This insert of genetic code allows the virus to transform the cell into an HIV producing “machine” that takes over the body.

Using the CCR5 work as a point of departure, the scientists designed a protein that mimics the receptor and simultaneously binds to two sites on the surface of the virus, preventing the virus from entering a host cell. When the virus encounters the protein, it springs into action as if infecting a cell. The changes the virus undergoes render it incapable of future attempts at infection and the HIV genetic code is trapped inside the protein instead of a dividing human cell.

The protein was tested in cell cultures, mice with humanized immune systems and non human primates given SIV. The level of protection exhibited by the engineered decoy protein far exceeds that of the strongest available anti-HIV antibodies in the body’s immune system. The next challenge for researchers at Scripps and elsewhere is to encourage cells to produce the protein on their own.