I must have missed it, because I'm sure that someone in this viruses-as-prey thread must have already pointed at hepatitis delta virus, adeno-associated virus, and some of the plant viroids. If not, then I just have. Ian -- Ian York (york at mbcrr.harvard.edu) Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115 Phone (617)-632-3921 Fax (617)-632-2627