Cytomegalovirus (CMV) is a particular threat to individuals with a suppressed immune system, such as transplant patients or people infected with the Human Immunodeficiency Virus (HIV). It is also responsible for causing severe abnormalities in the unborn child if the mother is infected during pregnancy, leading to deafness, visual impairment and sometimes brain damage.

Symptoms of infection are sore throat, fever and occasionally mild hepatitis (liver disease). After infection the virus stays in the body for life in a dormant state called latency. It is estimated that up to 80% of the population are latently infected with CMV. When the immune system is weakened the virus is able to reactivate and cause new and often more severe disease symptoms.

Proteins are complex molecules that are made in the cell when the instructions encoded in DNA (genes) are followed. They can be thought of as the machinery and building blocks of cells and viruses. To understand how proteins work, it is very useful to know their structure. Working out the structure of a protein is very difficult though, so scientists often have to try and predict it. This is done by finding related proteins for which the structure is known and using them as a template.

To make the structure of a protein easier to understand it is often drawn as a ribbon diagram. This ribbon diagram shows the predicted structure of a cytomegalovirus protein called UL146. Viruses often mimic human proteins, for example, to try and fight the body's immune system. UL146 is very similar to a human protein known as Interleukin 8 (IL-8), which is part of the immune response to infection. The known structure of IL-8 was used to work out this model of UL146.

During cytomegalovirus infection, different proteins are needed by the virus at different times, so the genes that encode these proteins are switched on and off. A microarray can be used to find out which genes are on and which are off at particular times in the infection.