Using a type of herpesvirus as a model system, Matthias Mann and colleagues, Max Planck Institute of Biochemistry, Martinsried, Germany, and their collaboration partners at the University of California, San Francisco, USA, have shown that the genome of this virus contains much more information than previously assumed. The genome of the herpesvirus had already been sequenced 20 years ago and it was thought theatby this all proteins that the virus produces could be predicted.

The scientists infected cells with herpesvirus and observed which proteins the virus produced inside the cell over a period of 72 hours. In order for proteins to be produced at all, the cell machinery must first make copies of the genetic material as intermediate products (RNA). Many novel RNA molecules which were in large part surprisingly short were discovered. The organization of information required for protein production in the virus genome was far more complex than previously assumed. Using mass spectrometry, the researchers were subsequently able to confirm directly the predicted viral proteins in the infected cell. This method enables an overview of the complete proteome of the virus-infected cell.

The results provide detailed insight into the complex mechanisms used by the virus and show that to understand the biology of the herpesvirus it is important to look at the products actually produced from the genome. Even human genes may be much more complex than the genome sequence itself indicates.

^{Image: © Max Planck Institute of Biochemistry/Kay Grünewald}

• Max Planck Gesellschaft, Munich, Germany