Flow cytometric detection of viruses

Representatives from several different virus families (Baculoviridae, Herpe sviridae, Myoviridae, Phycodnaviridae, Picornaviridae, Podoviridae, Retrovi ridae, and Siphoviridae) were stained using a variety of highly fluorescent nucleic acid specific dyes (SYBR Green I, SYBR Green IT, OliGreen, PicoGre en) and examined using a standard flow cytometer equipped with a standard 1 5 mW argon-ion laser. The highest green fluorescence intensities were obtai ned using SYBR Green I. DNA viruses with genome sizes between 48.5 and 300 kb could easily be detected. The fluorescence signals of the small genome-s ized RNA viruses (7.4-14.5 kb) were found at the limit of detection. No sig nificant linear relationship could be found between genome size and the gre en fluorescence intensity of the SYBR Green I stained virus preparations. T o our knowledge, this is the first report of detecting and discriminating b etween a wide range of different viruses directly using flow cytometry. Thi s rapid and precise assay represents a new and promising tool in the field of virology. (C) 2000 Elsevier Science B.V. All rights reserved.