A team of researchers at the Rush Medical Center in Chicago have published peer reviewed research in the journal Cell Host & Microbe showing how HIV evades the body’s immune system.
Natural killer (NK) cells are a kind of white blood cell that play a major role in the rejection of tumors and cells infected by viruses.
NK cells kill infected cells by releasing proteins that program a cell to die.
However, for more than two decades scientists have been puzzled by why NK cells do not destroy cells infected with HIV.
When HIV infects a cell it uses a protein called Vpr to take over the cell so that it can use the cell’s internal machinery to reproduce copies of itself.
However in doing this, it triggers the host cell to display a signal triggering molecule on its surface which NK cells recognise and latch onto to attack the cell.
Another protein produced by HIV prevents another kind of white blood cell, T cells, from attacking the cells it infects should also provoke the NK cells- however they still fail to attack HIV infected cells and now scientists know why.
The Rush Medical Center researchers have proved that the HIV virus produces a protein called Vpu which strips another set of proteins from the cell which the NK cells need to start delivering the proteins that would cause the cell to die.
“With this information, we now have a major new target for drug therapies that could potentially stop HIV and allow the body’s natural killer cells to do what they are designed to do – protect the body from this lethal virus,” said Edward Barker, an associate professor of immunology and microbiology at Rush University and the lead author of the study.
The discovery has excited Australian biomedical research company Biotron Ltd which has a drug that specifically targets the Vpu protein of HIV.
The drug has passed through early safety trials, and the company hopes to implement an efficacy trial with HIV-positive patients in the near future.
“This study is really important for Biotron,” said Biotron CEO Dr Michelle Miller.
“We have been working on developing drugs to target the Vpu protein of HIV for several years and, until recently, there has been very little known about exactly how Vpu works, despite good evidence that it is critical to the process of establishing HIV infections in specific cell types.”