Controlling the spread of HIV, the viral precursor to AIDS, is daunting but essential to getting the as-yet incurable epidemic under control. UC San Diego biochemist Leor Weinberger came up with a novel approach to the problem: he and his colleagues at San Diego and UCLA have engineered a particle that piggybacks on the virus as it moves between individuals and then competes with it once they're both inside a cell.
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In simulations, the researchers found that, over 30 years, these therapeutic interfering particles (TIPS) could reduce the number of people in Sub-Saharan Africa infected with HIV to one-thirtieth of the current level. With about 33.3 million people infected worldwide in 2009 and 68 percent of all people living with HIV located in Sub-Saharan Africa — according to the World Health Organization — this new technique's potential is tremendous.
TIPS are made from harmless fragments of HIV, omitting some key pieces of genetic information like how to self-replicate. In order to survive then, TIPS need to use DNA from the actual virus to copy themselves, meaning they cannot live on their own without the virus. The particles also contain a few gene sequences engineered to inhibit HIV and, because they derive from it, both viruses use some of the same proteins and must compete for them once inside a cell. This makes replication harder for the HIV. And since TIPS can last for years in a body, they might also help keep AIDS away for an extra 5 or 10 years.
The most rampant-spreaders of HIV tend to be intravenous drug users and sex workers, who are often more difficult to reach for prevention and drug treatment, leading to their disproportionately higher rates of infection. TIPS, with its latent virus-on-virus method of attack, could be a phenomenal way to address HIV infection in this group. Beyond simulations and cell cultures though, TIPS has not yet been tested in humans, though.
Weinberger is speaking to bioethicists and working carefully with his colleagues to asses the risk of using TIPS, since no one knows how these viral particles will evolve and mix with other genetic material once they're let loose. However in the UCSD news release, he did mention that similar transmissible disease-fighting methods, like the oral polio vaccine, are already in use. As the release puts it, “Public health officials see this transmission as a benefit; it is one reason why this form of polio vaccine was chosen for the worldwide effort to eradicate the disease.”
If SLC Puck taught me anything, it was that it's hard to fight the system from without. TIPS — and perhaps other engineered viruses in the future — could be modern medicine's way of getting inside an epidemic at the genetic level.
The original paper, published in PLoS Compuational Biology on March 17th is here.