Virus found to replicate four times faster than thought

Live video microscopy shows how vaccinia, a pox virus, spreads four times faster and in a different way than suspected earlier - a discovery that could open the way to the creation of better class of drugs to tackle some viruses.

Vaccinia is a pox virus and is the vaccine that was used to eradicate smallpox. Using live video microscopy.

Previously, viruses were thought to spread by entering a cell, replicating there, and then being released to infect new cells, so that the rate of spread of a virus would be limited by how quickly it could replicate in each cell.

Videos of virus-infected cells revealed that the bug spreads by surfing from cell to cell, using a mechanism that allows it to bounce past cells that are already infected and reach uninfected cells as quickly as possible.

Early after vaccinia infects a cell, it expresses two viral proteins on the cell surface, which marks the cell as infected.

When further virus particles reach the infected cell, these proteins cause the host cell to push out snake-like projections called 'actin tails,' which drive the virus particles away towards other cells that they can infect.

The particles thus bounce from one cell surface to another until they land on an uninfected cell.

In the study, the researchers prevented the virus from making the proteins needed to make the actin tails in the early stages of infecting a cell and showed that this slowed the spread of the virus dramatically.