Scientists have found a new way to block the HIV virus from entering healthy cells, and reported their findings in the journal Nature.
Lead researcher Michael Farzan, professor of infectious diseases at Scripps Research Institute, and colleagues believe that they have made major progress in the fight against the virus. Previous attempts at blocking the virus have not been entirely successful, but this time things may be different, writes Alice Park for Time.
How the method works
Farzan and his team used a gene therapy technique to place an HIV disruptor on the virus. As soon as it is attached to the surface of the virus, the peptide complex stops the HIV virus from entering the molecular locks on healthy cells, preventing further infection.
Another boon of this method is that the peptide complex does not differentiate between different strains of HIV; it has been shown to stick to all of the strains tested by the scientists, including HIV-1 and HIV-2 which transmit among human populations, and also simian strains which infect primates. In lab tests the disruptor neutralized 100% of the virus, which means that none of the cells were infected.
Previous research showed scientists how HIV infects healthy cells. The virus looks for a protein called CD4 to act as a receptor on immune cells, because CD4 acts as a “lock”. The HIV virus then uses three proteins of its viral coat as a “key” to unlock the cell.
The virus is capable of changing its shape to better fit inside the healthy cell, before replicating itself inside it. The so-called “gum” which Farzan’s team used is known as eCD4-Ig, and finds the “key” section of the HIV virus before sticking to it and rendering it useless. Another benefit is that the gum causes the virus to change shape in search of its lock, an irreversible process which means the virus ceases to be infectious.
Results so far would suggest that eCD4-Ig could effectively act as a vaccine against HIV. Lab tests on monkeys showed that of 4 specimens who were given gene therapy to receive eCD4-Ig, none of them were infected with the HIV virus despite multiple attempts to infect them.
Long-term protection would also seem to be provided by the gum. The treated monkeys have survived for over a year despite exposure to the HIV virus, while untreated monkeys have died.
Before we begin to think that a definitive HIV vaccine has been discovered, it is important to remember that the method is still a long way from being tested on humans. Previously, safety issues have arisen with gene therapy methods, as well as issues concerning how to control how much infected material is used, as well as where it is deposited.
Further research needed
One possible solution could be the introduction of the peptide in the form of an injection every few years. This strategy would enable infected patients to control the level of HIV infection, and also protect uninfected, high-risk patients from becoming infected.
None of this can become a reality until the method is proven to be safe, which will require a lot more information than four monkeys can provide. Farzan himself is aware of the limitations of the latest results, claiming that “things change when we get to humans and when we get to larger numbers. But the data in monkeys are as encouraging as one could hope.”
Sensational headlines may herald the arrival of an HIV vaccine, but Farzan himself is aware that this is just the first step in the battle to prevent the spread of HIV.