Scientists are genetically engineering immune systems to attack and destroy HIV.

HIV has been destroying lives and for decades with treatments inaccessible to many of the poorest communities. Even though scientists discovered the virus that causes AIDS in 1983, a vaccine or cure has remained elusive and more than 35 million people worldwide have died of the illness since the 1980s.

Now emerging medical science published in PLOS Pathogens is yielding positive results in vitro and in primates.

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The study described genetically modifying stem cells to produce immune-system T cells and other blood cells with a specific chimeric antigen receptor (CAR) that enables them to identify and attach to antigens on HIV-infected cells. Once attached, the CAR-T cell kills the infected cells. Even better, the genetic modifications also protect the CAR-T cells from becoming infected with HIV themselves. According to the study, with these modifications, the CAR-T cells can act as sentinels, offering a robust response to the virus in infected cells. It was the first time such a method yielded results in a relevant large-animal model. The study was small, but suggested scientists can genetically modify the immune system to better fight the virus.

Perhaps the most notable finding researchers documented was that the engineered cells killed HIV-infected cells in petri dishes and in two macaque monkeys for a full two years. “These results set the stage for future attempts to eradicate viral infection and provide more effective immune surveillance for HIV,” the study says.

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The technique did not eradicate infected cells in which the HIV virus was dormant. For that reason, future studies could focus on a combination approach to treatment. That would mean engineering cells to attack HIV infections while also making the blood system resistant to infection.

Gene therapy at the population level is totally untested and would be astronomically expensive as a cutting edge approach. CAR-T therapies for cancer currently cost about $500,000. People with HIV can live relatively normal lives by taking affordable antiretroviral therapy medication already on the market but any new approaches to stem the spread of the virus and eventually eradicate have been long awaited.