The genome of the human cytomegalovirus (HCMV) was first sequenced over 20 years ago, but researchers have now discovered that the common pathogen has a surprisingly complex protein-coding capacity as well.

The virus only causes birth defects in newborn infants and disease in adults with compromised immune systems, but it infects most humans on the planet. The new findings, published in the 23 November issue of Science, could help explain why HCMV is such a widespread and successful virus.