Injecting magnetic nanoparticles into the bloodstream could reveal the precise location of viruses, with early trials pinpointing viruses in body fluids and tissue samples and human trials just a few years away.

The injected nanoparticles are coated with antibodies to a particular virus so that they form clumps wherever the virus is present.

The clumps should be visible on conventional body scans, and the technique’s inventors, from Harvard Medical School’s Center for Molecular Imaging Research in Charlestown, Massachusetts, have already managed to detect viruses in body fluids and tissue samples.

They hope to begin detecting viruses in human patients within a few years, as much of the technology has already been tested for safety in humans.

Improving treatment

Pinpointing virus populations could help doctors improve treatment.

For HIV treatment, for example, a nanoparticle scan could reveal virus concentrations in lymph nodes.

A nanoparticle scan could also reveal whether viruses used in gene therapy to ferry DNA actually reach parts of the body for which they are intended.

Twice as fast

Currently, detecting viruses is done indirectly by capturing viral DNA and amplifying it through polymerase chain reaction, which takes about two hours.

“It’s cumbersome, takes time, gives you false positives and negatives, and only detects fragments of the virus,” Manuel Perez, head of the team developing the new technique, told New Scientist, in which the technique was first reported.

The new method can detect viruses in half the time.

Iron, sugar and antibodies

The technique uses particles just 50 nanometers wide.

The particles have a core of iron oxide and a coating of dextran, a sugar to which antibodies stick easily. The iron oxide cores are magnetized so that they can be detected by various scans.

A top coat of antibodies to the virus under investigation is added, and the particles are ready for use.

If a live virus is present, it will stick to the antibodies on the nanoparticles, forming a large cluster of particles that can then be detected through magnetic resonance imaging or nuclear magnetic resonance scans.

“The antibodies recognize specific proteins on the surface of the virus, and it makes the nanoparticles clump with the virus,” says Perez.

Successful detection

The nanoparticles have been added to samples of body fluids in lab tests, but in patients they would simply be injected.

The Harvard team has already successfully detected the herpes simplex virus, which causes cold sores, and an adenovirus, which causes colds, in blood samples.

Because similar particles to the ones used have already proven safe in humans in earlier prostate cancer detection, and because all the components used are already available commercially, Perez says the technique could rapidly become available in clinics.

More here.