Rabies virus hijacks nerve transport system to hasten to brain

Date: Sep-03-2014Rabies is a disease caused by a virus that targets the brain and nervous system once it

gets into a new host, usually via the bite of an infected animal. Now new research led by Tel

Aviv University in Israel has discovered the molecular mechanism that the virus uses to get from

the bite wound to the brain as quickly as possible.

Rabies, which causes inflammation in the brain and spinal cord, is almost always fatal if not treated early.

The researchers report their findings in the journal PLOS Pathogens.

Rabies, which causes inflammation in the brain and spinal cord, is almost always fatal if not treated early. According to the World Health Organization, rabies occurs in more than 150 countries, and kills over 60,000 people every year, mostly in Asia and Africa.

Many disease pathogens spread through the body via the bloodstream, powered along by the

pumping of the heart. But those that travel outside the bloodstream have to use some other means

of transport.

Rabies virus uses the network of nerve cells that link all parts of the body to the brain. In

particular, it makes use of nerve cells in the peripheral nervous system, which connects various

parts of the body to the central nervous system that comprises the brain and the spinal

cord.

Axons or fibers in the peripheral nervous system can be hundreds of times longer than the cell bodies they

belong to, and not only do they transport electrical signals they also transport molecules over

long distances in the body.

For their study, senior author Dr. Eran Perlson, of Tel Aviv's Sackler Faculty of Medicine

and Sagol School of Neuroscience, and colleagues were particularly interested in a protein

called the p75NTR receptor, which is found on the tips of peripheral neurons.

They discovered that the rabies virus uses the receptor in the same way as another small

molecule called NGF or nerve growth factor. NGF binds to p75NTR, where it is absorbed into the neuron and

travels to the cell body in tiny acidic bubbles called vesicles.

Using a method called live cell imaging, the team saw how the rabies virus entered at nerve

terminals and traveled along axons.

Rabies virus needs to bind to p75NTR receptor to get to brain quickly

To test how important the receptor might be to the virus, the researchers grew nerve cells

that had no p75NTR. They found while the virus was able to travel along the axons without

p75NTR, it did so far less effectively: progress was slow, erratic, and infrequent, and the

vesicles sometimes even went in the wrong direction.

The team concluded that for fast and effective transport, the rabies virus needs to be

accompanied by the p75NTR receptor.

They found when bound to p75NTR, the virus traveled about 8 cm per day, which is about 40%

faster than the speed at which the receptor travels when bound to its regular partner, NGF.

The authors conclude that their findings show not only does the rabies virus hijack the

transport system of neurons, but it also appears to "manipulate the axonal transport machinery

to facilitate its own arrival at the cell body, and from there to the central nervous system at

maximum speed."

One known reservoir of rabies is bats, which also harbour other deadly human diseases. In

August 2013, Medical News Today learned how MERS or Middle East respiratory syndrome may have started in bats in Saudi Arabia.

Written by Catharine Paddock PhD

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Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.