Human enzyme helps Ebola virus invade cells

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As the deadly outbreak of Marburg virus continues to claim lives in Angola, researchers have worked out how the closely related Ebola virus invades human cells.

The findings could lead to a treatment for the diseases, which each kill up to 90 per cent of those infected.

The researchers, led by James Cunningham of Harvard Medical School, United States, showed that a human enzyme helps Ebola virus fuse with the cells of people it infects.

Their results were published online by the journal Science yesterday (14 April).

The enzyme, called cathepsin B, digests a protein the virus uses to attach to a human cell. This destabilises the cell's outer membrane, allowing the virus to fuse with it.

In a laboratory experiment, the team treated kidney cells so that cathepsin B would not function, then exposed them to the Ebola virus. They found that this reduced the virus's ability to multiply, and suggest the approach could lead to a drug against the virus.

Cunningham told SciDev.Net said that his team is now testing whether the related Marburg virus uses the same strategy to invade human cells.

Angola is currently suffering from the worst ever outbreak of Marburg virus, with 215 dead. The vast majority of casualties were reported the last month (see Worst ever outbreak of Marburg virus hits Angola).

If blocking cathepsin B works against Ebola, it might also work against the Marburg virus, says Javad Aman who studies Marburg at the United States Army Medical Research Institute of Infectious Diseases.

Aman points out that cathepsin enzymes are important for the body's immune system, so blocking them could cause severe side effects. 

But he adds that because people infected with Ebola or Marburg virus usually only need treatment for 10-14 days, this could make any side effects acceptable.

Link to full paper in Science