Could This New Compound Replace the Need for an HIV Vaccine?

A new HIV-blocking compound could “circumvent the need for a conventional vaccine,” according to a study published in the journal Nature. The HIV virus normally attaches to receptors outside white blood cells by using spike-like appendages. The virus is shaped in such a way that it can attach to two different receptors. Normal human antibodies can block one of spikes on the virus, but not the other.

Researchers, whose work was supported by the National Institute of Allergy and Infectious Diseases, say they have found a new coumpound which resembles normal antibodies but has both a head and a tail, and can therefore simultaneously block two receptors at once.

If the HIV virus can’t attach to either receptor, it cannot infect the cell and is rendered harmless. While antibody cocktails have been developed that can block one or two strains of HIV, they haven’t been effective against all forms. But that’s where this new experimental compound has separated itself from the pack.

In scientific jargon, the paper reports that the proten created (eCD4-Ig) "efficiently neutralized 100% of a diverse panel of neutralization-resistant HIV-1, HIV-2 and simian immunodeficiency virus isolates, including a comprehensive set of isolates resistant to the CD4-binding site bNAbs VRC01, NIH45-46 and 3BNC117.”

What this means is that the compound has proven to be effective — even against the most virulent and treatment-resistant strains of HIV.

So far the study has been a limited one, exclusively tested on monkeys; but the researchers were thrilled that the four monkeys given the new compound remained HIV free, despite repeated attempts to infect them over a 12-month period.

“Our compound is the broadest and most potent entry inhibitor described so far,” notes Dr. Michael Farzan of The Scripps Research Institute, lead researcher on the project.

The researchers created a “gene therapy vector” that was injected into muscles to produce the eCD4-IG protein.

“It’s very impressive, and the method is quite promising,” Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, told The New York Times about the study. “But it’s still just in an animal model, so we’ll need to see evidence of whether it works in humans.”

According to Dr. Farzan, the next step will be to test the compound in infected monkeys and see if it is as effective as antiretroviral medicines in preventing HIV from replicating further. If things go well the researchers will launch human trials.