PARIS, May 24, 2006 - Lab teams fighting AIDS have been given a powerful new tool in the form of the first high-magnification 3D image of the human immunodeficiency virus (HIV), the British journal Nature reports today.

Molecular biologists led by Kenneth Roux of Florida State University used a technique called cryoelectron microscopy tomography to magnify the pathogen 43,200 times to get details as small as a few nanometres (billionths of a metre) across.

Of particular interest are spikes that stud the coat of the virus and allow it to latch onto human immune cells and fuse with them.

HIV has around 14 of these spikes, which are placed unevenly around the viral surface.

The equivalent virus in monkeys, simian immunodeficiency virus (SIV), has many more - 73 - that are located more evenly on its surface. The belief is that the more spikes a virus has, the greater its chance of infection.
The extremely detailed close-ups show that the spikes are in fact more like nobbly heads, placed upon a tripod of small stalks that are attached the virus' surface membrane.

The spikes consist of two proteins, gp120 and gp41, which have long been eyed as the most promising targets for a vaccine.

One of the biggest problems for vaccine engineers has been to prime antibodies so that they recognise the shape of these proteins and stick to them, a task that may be easier with the ultra-fine 3D picture, the researchers hope.

Around 40.3 million around the world have HIV or AIDS, according to the latest toll compiled by the World Health Organisation (WHO) and UNAIDS.

The disease was identified a quarter-century ago, but there is still no vaccine or cure, although antiretroviral drugs can make the condition manageable.