At last, hope of cure for the common cold

Steve Connor

Scientists have been able to show for the first time that the body's immune defences can destroy the common cold virus after it has actually invaded the inner sanctum of a human cell.

The dramatic breakthrough, which could affect millions of lives, has demonstrated a feat that was believed until now to be impossible.

The discovery opens the door to the development of a new class of antiviral drugs that work by enhancing this natural virus-killing machinery of the cell. Scientists believe the first clinical trials of new drugs based on the findings could begin within two to five years.

The researchers said that many other viruses responsible for a range of diseases could also be targeted by the new approach.

They include the norovirus, which causes winter vomiting, and rotavirus, which results in severe diarrhoea and kills thousands of children in developing countries.

Viruses are still mankind's biggest killers, essentially because they can get inside cells where they can hide away from the body's immune defences and the powerful antibiotic drugs that have proved invaluable against bacterial infections.

Trigger

However, a study by a team of researchers from the Laboratory of Molecular Biology in Cambridge has shown that anti-viral antibodies can, in fact, enter the cell with the invading virus, where they are able to trigger the rapid destruction of the foreign invader.

"In any immunology textbook you will read that once a virus makes it into a cell, that is game over because the cell is now infected. At that point there is nothing the immune response can do other than kill that cell," said Leo James, who led the research team.

But studies have found that the antibodies produced by the immune system, which recognise and attack invading viruses, actually ride piggyback into the inside of a cell with the invading virus.

Once inside the cell, the presence of the antibody is recognised by a naturally occurring protein in the cell called TRIM21 which in turn activates a powerful virus-crushing machinery that can eliminate the virus within two hours -- long before it has the chance to hijack the cell to start making its own viral proteins.

One possibility is that the protein TRIM21 could be used in a nasal spray to combat the many types of viruses that cause the common cold.

"The advantage is that you can use that one drug against potentially lots of viral infections," said Dr James.

hnews@herald.ie