1. T. G. Senkevich, J. J. Bugert, J. R. Sisler, B. Moss, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0455, USA.
2. E. V. Koonin, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20892, USA.
3. G. Darai, Institut für Medizinische Virologie, Universität Heidelberg, 69120 Heidelberg, Germany.