Gene therapy could provide hope for another “functional cure”, a one-off treatment without the use of ARVs.
A cell is the smallest basic unit of all living things (except viruses which are special). The human body is made of 10 000 000 000 0000 cells and they are very small. We have about 200 different types of cells, which have special functions, for example red blood cells are involved in helping us breathe and white blood cells help us fight disease through our immune response.
HIV once in the body infects CD4 cells, which are important cells for our immune response. This recognition process is almost like a lock and key, with HIV having an exact key that recognises a lock on the CD4 T cells, it unlocks and enters the cell. Once in the cell, HIV can either go to sleep for a very long time (this is when people have no illness) or it can make several copies of itself and eventually kill the cell and infect other cells.
Inside our cells we have genes. Genes provide cells with important information that helps them function and in turn helps our body function. Gene therapy is a complex procedure. There are a number of different approaches being studied. Some researchers look at stopping this lock and key recognition process between HIV and CD4 cells. Other scientists look at ways of stopping the virus from making copies of itself.
At Stanford University in the USA, they are inserting a series of HIV-resistant genes into CD4 cells. HIV is then unable to recognise and infect these “new” CD4 cells.
In Australia, instead of targeting the genes in the CD4 cells, researchers are targeting the genes in HIV. A team of researchers have developed a virus that attacks the HIV virus. This virus infects the HIV and prevents it from making copies of itself. This kind of gene therapy would not prevent or cure HIV, clients would still have HIV, but the virus would be unable to make copies of itself. So, the immune system would remain healthy and the client would never progress to Aids.
Gene therapy has been shown to work. The Berlin Patient, the only known adult “cured” of HIV received a bone marrow transplant from a donor who had natural resistance to HIV. The donor did not produce the “lock” on CD4 cells that HIV recognises. Unfortunately, the approach of using a bone marrow transplant is not effective as a large-scale treatment because there are only a few people in the world who are naturally resistant to HIV. Scientists are looking into other avenues such as getting stem cells from persons with HIV, modifying the genes in those stem cells and putting them back into the person’s body. This has been shown to be effective in the USA.
There are a number of drawbacks to gene therapy. It is very expensive, but if found to be effective as a one off treatment, it would be much cheaper than lifelong ART.