1. Wadsworth Center, Bacteriology Laboratory, New York State Department of Health, PO Box 22002, Albany, NY 12201, USA
2. Present address: Wadsworth Center, Virology Laboratory, New York State Department of Health, PO Box 22002, Albany, NY 12201, USA.
3. Department of Biological Sciences, Sierra College, 5100 Sierra College Boulevard, Rocklin, CA 95677, USA
4. Present address: University of California, Davis Medical Center, 2315 Stockton Boulevard, Sacramento, CA 95817, USA.
5. Department of Biomedical Sciences, State University of New York, PO Box 22002, Albany, NY 12201, USA