Control of CD4 Function by Disulphide-Bond Switching [ 2007 - 2008 ]

Research Grant

Researchers: Prof Philip Hogg (Principal investigator) ,  Dr Akiko Maekawa

Brief description CD4 is a cell-surface protein that has two functions in the human body, a good one and a bad one. Its good function is as a checkpoint for development of the immune system and for response of the immune system to infection. It helps immune cells known as T cells to recognize and dispose of a foreign particle in the body. Its bad function is that it is one of two proteins that enable the HIV virus to enter and destroy immune cells. The HIV virus binds to CD4 on immune cells, which leads to fusion of the viral and immune cell surfaces and entry of the virus into the cell. Once inside the immune cell the virus reproduces itself and goes on to kill more immune cells. AIDS results when too many immune cells are killed. We have discovered that CD4 exists in three different forms on the immune cell surface; an oxidized, reduced or dimeric form. These different forms result from a molecular switch we discovered in CD4. We have suggested that the good and bad functions of CD4 are mediated by different forms of CD4. The good function is mediated by dimeric CD4, while the bad function is mediated by reduced CD4. The purpose of this application is to test this hypothesis. If we are correct then our findings will have significant implications for our understanding of how the immune system responds to a foreign invader and how HIV-AIDS destroys the immune system. This knowledge could be used to develop drugs that suppress the immune system when required, such as in organ transplantation, and that fight HIV-AIDS.

Funding Amount $AUD 252,761.74

Funding Scheme NHMRC Project Grants

Notes Standard Project Grant