a defined quantity of a nonhuman control virus (seal herpes virus [SHV], kindly provided by H. G. M. Niesters, University of Rotterdam, The Netherlands) was spiked into each sample prior to DNA and RNA extraction. Since constant DNA quantities of the control virus are coextracted even when RNA isolation kits are used (H. G. M. Niesters, personal communication; our own unpublished observations), the virus can also serve as a control in RNA virus detection assays.

5 nM fluorescein in 0.01 M NaOH was measured in black 96-well microplates