How cancer-causing virus clings to our DNA decoded

Scientists have unveiled how a cancer-causing virus anchors itself to our DNA, paving the way for doctors to treat incurable diseases by flushing out viruses that permanently embed themselves in human cells.

The researchers used a microscope built by them to unveil the structure of the tether used by a virus called Kaposi's sarcoma-associated herpesvirus (KSHV).

Until now, such tethers have largely eluded scientists because they are so diabolically small, defying even the most high-tech approaches to determining their form.

"We're seeing things on the order of 8,000 times smaller than a human hair," said M Mitchell Smith, from University of Virginia (UVA) in the US, who built the microscope piece-by-piece.

"The reason we can't get rid of these viruses is because we can't figure out a way to get their DNA out of the nucleus, out of the cell," said Dean H Kedes, UVA researcher.

"They depend on this 'tether' to remain anchored to the DNA within our cells, and to remain attached even as the cells divide. This tether is a key factor to disrupt in devising a cure," said Kedes.

The researchers used fluorescent antibodies to mark individual molecules on the tether and then recorded their location in space. They then combined the resulting images to create an outline of the shape, a bit like mapping a city from thousands of GPS signals.

To complete their 3D portrait of the virus, they combined their results with information drawn from other imaging techniques, such as X-ray crystallography.

The result is the most complete portrait of the tether ever created - information that likely will prove vital for cutting the rope on the virus' grappling hook.

The researchers envision using the approach for many other stubborn viruses, such as Epstein-Barr (the virus that causes infectious mononucleosis) and HPV (human papillomavirus).