HIV Drug Candidate Shows Promise as Vaccine

February 18, 2015
Meghan Ross, Associate Editor

A new drug candidate developed by scientists from more than a dozen research institutions may function as an effective HIV-1 vaccine.

A new drug candidate developed by scientists from more than a dozen research institutions may function as an effective HIV-1 vaccine, according to a new study published in Nature.

As HIV infects a cell, the virus attaches to 2 receptors: CD4 and CCR5. When the CD4 lymphocyte, part of the immune system, is compromised, the cell becomes a factory for making HIV.

The new drug candidate binds to 2 sites on the virus surface in order to prevent HIV from entering the cell.

Adeno-associated virus (AAV) vectors can express HIV-1 broadly neutralizing antibodies (bNAbs). Using AAV-delivered eCD4-Ig, which is a fusion of CD4-Ig and CCR5-mimetic sulfopeptide, an effective vaccine that is more potent and powerful than bNAbs could be manufactured.

“What we’ve shown is that an exceptionally broad and potent HIV inhibitor can be used together with a gene-therapy vector to provide protection against very high-challenge doses of HIV,” study author Michael Farzan, PhD, a professor in the Department of Infectious Diseases at the Scripps Research Institute, told Pharmacy Times.

The drug candidate can stop 100% of a panel of neutralization-resistant HIV-1, HIV-2, and simian immunodeficiency virus, the researchers found. This compound differs from antibodies, which are not capable of neutralizing large fractions of HIV-1 strains, according to the study authors.

“[E]ven the best bNAbs neutralize 10% to 50% of HIV-1 isolates inefficiently, suggesting that high concentrations of these antibodies would be necessary to achieve general protection,” the authors wrote.

However, the AAV can be injected into muscle tissue and manipulate the cells to create the new protective protein. The scientists’ compound can also protect against high doses of virus for at least 8 months after injection.

“Our data suggest that AAV-delivered eCD4-Ig can function like an effective HIV-1 vaccine,” the authors concluded.