Scientists say they have bred super immune cells that are able to recognize and destroy many variants of HIV-infected cells. The news comes after a bleak year for AIDS research that saw the failure of the Merck HIV vaccine trial and the cancellation of another. “I think the field as a whole has been taking a step back and thinking we need some different ideas all together,” [New Scientist] said immunologist Philip Goulder.
The researchers’ novel idea was to create a mutant type of immune cells, called T-cells, that would target SL9, a protein that is part of HIV and also appears on the surface of HIV-infected cells. They started with particularly strong T-cells taken from a patient who had resisted HIV infection. “When we tested the T cells from this patient, it looked as if he was responding to a number of those variants that normally escape the immune system,” [The Guardian] said researcher Brent Jakobsen. Through a process of directed evolution, the researchers selected for T-cell mutants that had receptors enhanced to recognize and latch onto SL9. In Nature Medicine [subscription required], the researchers report that in lab cultures of human cells, the souped-up T-cells easily destroyed HIV-infected cells and even recognized tricky variants of the SLP9 protein.
One reason HIV has been able to skirt our immune systems, drugs and vaccines is the virus’s chameleon-like behaviour – thanks to a genome that mutates with ease, HIV can quickly change guise to evade an attack. But some parts of HIV are so vital to its functioning that changes result in dead or severely compromised viruses [New Scientist]; the SL9 protein is one of these essential parts of HIV’s anatomy.
If the new and improved immune cell fighters don’t kill the virus outright, they could still have a beneficial impact. “In the face of our engineered assassin cells, the virus will either die or be forced to change its disguises again, weakening itself along the way,” [BBC News] said researcher Andy Sewell. Billions of these elite assassin T-cell could reportedly be created in just two weeks.
Next, the researchers will test the T-cells in mice engineered to produce human immune cells and infected with HIV. They hope to begin trials in human patients as soon as next year. Treating patients will involve taking a blood sample and adding an engineered virus containing genes for the improved T cell receptor. The patient’s own T cells then take up the genes and so are equipped with the improved receptor. These cells are then injected back into the patient [The Guardian]. There are caveats: One is that the assassin T-cells may be too specific and not recognize variants of SL9 that exist in different human races. Another is that they may not be specific enough and could attack other proteins, including human proteins.
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