Look at: http://www-micro.msb.le.ac.uk/335/ICTV.html Dr Alan J. Cann PhD, Department of Microbiology & Immunology, University of Leicester, P.O. Box 138, Medical Sciences Building, University Road, Leicester LE1 9HN, UK. Email: nna at le.ac.uk http://www.le.ac.uk/CWIS/AD/MI/ST/nna.html