Studies Examine Use Of Modified CD4+ T Cells, Vaccine To Fight HIV/AIDS

Main Category: HIV / AIDS
Also Included In: Immune System / Vaccines;  Genetics
Article Date: 12 Nov 2008 - 6:00 PST

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A new therapy that involves engineering an HIV-positive individual's own immune system to fight the virus more effectively has been developed by researchers at Adaptimmune in Oxford, England, London's Guardian reports (Randerson, Guardian, 11/10). The therapy involves genetically engineering CD4+ T cells, called "assassin" cells by the researchers, which were able to recognize other cells infected with HIV and slow the spread of the virus. According to Reuters, if the therapy -- which worked in laboratory tests -- is effective in humans, it could provide a new method of treating HIV (Fox, Reuters, 11/9). The therapy was detailed in a study published on Sunday in Nature Medicine.

According to the Guardian, researchers began to pursue a different approach to a traditional HIV vaccine after investigating a patient who had "resisted his HIV infection particularly effectively." Researcher Bent Jakobsen said, "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." In developing the therapy, the Guardian reports that the researchers first isolated the T cell receptor protein, which can recognize HIV antigens, and then improved its ability to recognize HIV further by randomly mutating it. The therapy will involve taking blood samples and adding an engineered virus that contains genes for the improved T cell receptor. A patient's T cells then take up the genes and are thus equipped with the improved receptor. These cells are then injected back in the patient (Guardian, 11/10).

James Riley, a University of Pennsylvania researcher involved in the study, said that not only could the engineered T cells see HIV strains that had escaped detection by natural T cells, "but the engineered T cells responded in a much more vigorous fashion so that far fewer T cells were required to control infection." Researcher Andy Sewell of Cardiff University said, "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" (Reuters, 11/9). The Guardian reports that a clinical trial of the therapy will take place next summer among 35 participants at the University of Pennsylvania (Guardian, 11/10).

In related news, a second, unrelated report by researchers testing Crucell's experimental HIV/AIDS vaccine that is based on T cells said it was effective among six rhesus monkeys. For the study, published in the journal Nature, the monkeys were injected with a lethal dose of SIV, the simian version of HIV. When injected, they were able to stop replication of the virus and remained healthy for more than 500 days after infection (AFP/Google.com, 11/9).

According to Dan Barouch of Beth Israel Deaconess Medical Center and Harvard Medical School, the study shows there is still hope for developing an effective HIV/AIDS vaccine (Reuters, 11/9). Barouch added, "Despite the disappointing setbacks in HIV-1 vaccine development this past year, our findings suggest that we're not at the end of the road when it comes to T cell vaccines" (AFP/Google.com, 11/9).

The Nature Medicine study is available online. The Nature study is also available online.

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