HIV, the virus which leads to AIDS and which affects 40 million people across the world, has been seen in 3D detail for the first time by Oxford scientists and their colleagues in Heidelberg and Munich.
The virus, which is around 60 times smaller than a red blood cell, is far too small for normal microscopes. Electron microscopes and X-rays can ‘see’ it, but often give unsatisfactory images because the virus varies so much in size and shape: one of the unique features of HIV is this size variation, which is in contrast to the uniformity of most viruses.
Professor Stephen Fuller from Oxford’s Wellcome Trust Centre for Human Genetics and his colleagues used a technique called cryo-electron tomography to look in detail at the morphology of the virus. The technique has been used to see the virus before, but this painstaking attempt reveals the three-dimensional structure for the first time. The team took images of the individual viruses from hundreds of different angles. These images were then combined using a computer, giving an unprecedented three-dimensional view of the deadly agent, published in the journal Structure.
An HIV particle, like any virus, is not a cell but rather is strands of genetic code wrapped in protein. Viruses invade living cells and take them over by usurping the cell’s genetic code with the virus’s genetic code (which contains the instruction ‘replicate’).