HIV Virus Eliminated from Infected Mice Cells
A new CRISPR-based method has managed to eliminate HIV in mice, for the first time potentially curing the lifelong illness of HIV/AIDs. Clinical trials will start next year to identify if the same method could be used to cure humans.
HIV is a virus which attacks the immune cells in the body, leaving it susceptible to life-threatening diseases. Currently people with the disease can manage it by taking daily anti-viral medication, which lowers the amount of virus in the bloodstream. However, the virus can also infiltrate the body’s cells and insert itself into the DNA. This is known as the dormant form of HIV, which cannot be eliminated using the anti-viral medication. HIV patients therefore must stay on this medication for life, which until recently has been the only option. However, the new treatment using CRISPR has successfully eliminated the dormant HIV virus within infected mice cells, which could enable a complete cure for HIV in humans.
CRISPR is a pioneering genetic technique which allows precise and easy editing or elimination of DNA sequences in cells. CRISPR is made up of repeating sequences of DNA which are made complementary to the gene that scientists want to eliminate. Once the CRISPR sequence binds to the desired gene the associated protein to CRISPR, Cas-9, acts as a molecular scissor and removes it from the cell DNA. The HIV infected mice were injected with a harmless virus which produced a CRISPR sequence targeted to the HIV gene inside their bodies.
A third of the mice were cured of HIV using a combination treatment of CRISPR and a potent form of the currently used HIV anti-viral medication. This was due to the HIV virus replicating too quickly for the CRISPR method to be effective on its own. The treatment could then be targeted directly at the infected immune cells where the HIV gene was expressed, using fat-soluble drug molecules contained in a water-soluble cage. In the cured mice, the treatment was able to completely remove the HIV gene in the infected cells.
After the initial treatment the mice were not given any further anti-viral medication. There was no viral surge in their blood for up to five weeks and when dissected genetic tests could not find any remaining virus.
Scientists still hold some concerns on using CRISPR in humans due to the possibility that CRISPR could also edit genes that it is not targeted to. There are fears that this unintended side-affect, known as off-target mutations, could lead to other genetic diseases such as cancer. However, in this trial there were no evidence of off-target mutations.
If the primate trials are successful human trials could start as early as next year. HIV patients currently must take daily pills to keep the disease under control, so a permanent cure could increase patient quality of life dramatically.