A novel vaccine for the AIDS virus may become possible through a new compound proving highly effective in preventing HIV infection. While testing has only been carried out on monkeys so far, the scientists behind the development say that with its ability to block multiple strains of infection at once, the technique has huge potential to one day provide long-lasting protection against the deadly virus.
The HIV virus spreads infection by using spikes that coat its surface to latch onto healthy cells. More specifically, it does this by targeting two receptors on the cells' surface known as CD4 and CCR5. This enables the HIV to fuse with the healthy cell and inject its own genetic material, converting it to a site for reproducing HIV.
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Whereas conventional antibodies have only been able to block one, the new approach focuses on shutting off both of these receptor sites. Led by Michael Farzan, a professor at The Scripps Research Institute (TSRI), the researchers were building on the knowledge that the CCR5 receptor possesses unusual modifications in the HIV-binding region. The team produced a new drug candidate capable of binding to both receptors at once and blocking entry of HIV into the healthy cell as a consequence.
"Our compound is the broadest and most potent entry inhibitor described so far," says Farzan. "Unlike antibodies, which fail to neutralize a large fraction of HIV-1 strains, our protein has been effective against all strains tested, raising the possibility it could offer an effective HIV vaccine alternative."
This includes protections against the strains HIV-2 and simian immunodeficiency virus (SIV). In fact, in testing the drug in monkeys, the researchers say that once injected it behaves much like HIV itself, transforming cells into "factories" that then reproduce the protein to offer lasting protection, potentially for years or even decades. The monkeys in question, once administered the new compound, repelled several attempts to infect them with SIV.
According to The New York Times, Farzan and his team will now look to test the compound in already infected monkeys to see if it can also serve as an antiretroviral medicine, that is, drugs that stop the growth of HIV. If it is shown to be effective, it is hoped that human trials will follow.
The findings were published in the journal Nature.