1. Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland.
2. SIB Swiss Institute of Bioinformatics, Basel, Switzerland.
3. Institute of Medical Virology, University of Zurich, Zurich, Switzerland.
4. Department of Mathematics and Computer Science, University of Basel, Basel, Switzerland.
5. Department of Molecular Microbiology and Biotechnology, Tel-Aviv University, Tel-Aviv, Israel.
6. International Computer Science Institute, Berkeley, California.