Protein found to inhibit body's response to HIV

Researchers have discovered a second reason that the body's immune system is unable to fight the HIV virus.

Scientists at the Partners AIDS Research Center at Massachusetts General Hospital (PARC-MGH) have discovered a second molecular "switch" that is responsible for turning off the immune system's response.

The regulatory protein CTLA-4 has been found to inhibit the action of HIV-specific CD4 T cells that control the body's overall response to the virus.

"We've shown that a known regulator of the immune system, CTLA-4, is present in elevated levels on the virus-specific CD4 cells that should be managing the body's response against HIV," said Daniel Kaufmann, managing director of PARC.

"We also found that CTLA-4 expression rises as HIV infection progresses and that the molecule switches off CD4 cell function in a way that appears to be reversible."

A molecule called PD-1 was identified last year by the same team as responsible for suppressing the CD8 T cells that should destroy virus-infected cells.

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